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Klenotic PA, Yu EW. Structural analysis of resistance-nodulation cell division transporters. Microbiol Mol Biol Rev 2024; 88:e0019823. [PMID: 38551344 PMCID: PMC11332337 DOI: 10.1128/mmbr.00198-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2024] Open
Abstract
SUMMARYInfectious bacteria have both intrinsic and acquired mechanisms to combat harmful biocides that enter the cell. Through adaptive pressures, many of these pathogens have become resistant to many, if not all, of the current antibiotics used today to treat these often deadly infections. One prominent mechanism is the upregulation of efflux systems, especially the resistance-nodulation-cell division class of exporters. These tripartite systems consist of an inner membrane transporter coupled with a periplasmic adaptor protein and an outer membrane channel to efficiently transport a diverse array of substrates from inside the cell to the extracellular space. Detailed mechanistic insight into how these inner membrane transporters recognize and shuttle their substrates can ultimately inform both new antibiotic and efflux pump inhibitor design. This review examines the structural basis of substrate recognition of these pumps and the molecular mechanisms underlying multidrug extrusion, which in turn mediate antimicrobial resistance in bacterial pathogens.
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Affiliation(s)
- Philip A. Klenotic
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Edward W. Yu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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2
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Hamami E, Huo W, Hernandez-Bird J, Castaneda A, Bai J, Syal S, Ortiz-Marquez JC, van Opijnen T, Geisinger E, Isberg RR. Identification of Determinants that Allow Maintenance of High-Level Fluoroquinolone Resistance in Acinetobacter baumannii. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.03.560562. [PMID: 38645180 PMCID: PMC11030222 DOI: 10.1101/2023.10.03.560562] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Acinetobacter baumannii is associated with multidrug resistant (MDR) infections in healthcare settings, with fluoroquinolones such as ciprofloxacin being currently ineffective. Clinical isolates largely harbor mutations in the GyrA and TopoIV fluoroquinolone targets, as well as mutations that increase expression of drug resistance-nodulation-division (RND) efflux pumps. Factors critical for maintaining fitness levels of pump overproducers are uncharacterized despite their prevalence in clinical isolates. We here identify proteins that contribute to the fitness of FQR strains overexpressing three known RND systems using high-density insertion mutagenesis. Overproduction of the AdeFGH efflux pump caused hypersensitization to defects in outer membrane homeostatic regulation, including lesions that reduced LOS biosynthesis and blocked production of the major A. baumannii porin. In contrast, AdeAB pump overproduction, which does not affect the outer membrane pump component, was relatively tolerant to loss of these functions, consistent with outer membrane protein overproduction being the primary disruptive component. Surprisingly, overproduction of proton-transporting efflux pumps had little impact on cytosolic pH, consistent with a compensatory response to pump activity. The most striking transcriptional changes were associated with AdeFGH pump overproduction, resulting in activation of the phenylacetate (PAA) degradation regulon. Disruption of the PAA pathway resulted in cytosolic acidification and defective expression of genes involved in protection from peroxide stress. These results indicate that the RND outer membrane protein overproduction is compensated by cytoplasmic buffering and maintenance of outer membrane integrity in A. baumannii to facilitate fitness of FQR isolates.
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Affiliation(s)
- Efrat Hamami
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
| | - Wenwen Huo
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
| | - Juan Hernandez-Bird
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
| | | | - Jinna Bai
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Sapna Syal
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
| | - Juan C Ortiz-Marquez
- Department of Biology, Boston College, Chestnut Hill, MA 02135 USA
- Innovation Laboratory, Broad Institute, Cambridge, MA 02412, USA
| | - Tim van Opijnen
- Innovation Laboratory, Broad Institute, Cambridge, MA 02412, USA
| | - Edward Geisinger
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Ralph R Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
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3
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Sykes EME, Mateo-Estrada V, Engelberg R, Muzaleva A, Zhanel G, Dettman J, Chapados J, Gerdis S, Akineden Ö, Khan IUH, Castillo-Ramírez S, Kumar A. Phylogenomic and phenotypic analyses highlight the diversity of antibiotic resistance and virulence in both human and non-human Acinetobacter baumannii. mSphere 2024; 9:e0074123. [PMID: 38440986 PMCID: PMC10964423 DOI: 10.1128/msphere.00741-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 02/15/2024] [Indexed: 03/06/2024] Open
Abstract
Acinetobacter baumannii is a Gram-negative, opportunistic pathogen that causes infections in the immunocompromised. With a high incidence of muti-drug resistance, carbapenem-resistant A. baumannii is designated as a priority 1 pathogen by the WHO. The current literature has expertly characterized clinical isolates of A. baumannii. As the challenge of these infections has recently been classified as a One Health issue, we set out to explore the diversity of isolates from human and non-clinical sources, such as agricultural surface water, urban streams, various effluents from wastewater treatment plants, and food (tank milk); and, importantly, these isolates came from a wide geographic distribution. Phylogenomic analysis considering almost 200 isolates showed that our diverse set is well-differentiated from the main international clones of A. baumannii. We discovered novel sequence types in both hospital and non-clinical settings and five strains that overexpress the resistance-nodulation-division efflux pump adeIJK without changes in susceptibility reflected by this overexpression. Furthermore, we detected a bla ADC-79 in a non-human isolate despite its sensitivity to all antibiotics. There was no significant differentiation between the virulence profiles of clinical and non-clinical isolates in the Galleria mellonella insect model of virulence, suggesting that virulence is neither dependent on geographic origin nor isolation source. The detection of antibiotic resistance and virulence genes in non-human strains suggests that these isolates may act as a genetic reservoir for clinical strains. This endorses the notion that in order to combat multi-drug-resistant infection caused by A. baumannii, a One Health approach is required, and a deeper understanding of non-clinical strains must be achieved.IMPORTANCEThe global crisis of antibiotic resistance is a silent one. More and more bacteria are becoming resistant to all antibiotics available for treatment, leaving no options remaining. This includes Acinetobacter baumannii. This Gram-negative, opportunistic pathogen shows a high frequency of multi-drug resistance, and many strains are resistant to the last-resort drugs carbapenem and colistin. Research has focused on strains of clinical origin, but there is a knowledge gap regarding virulence traits, particularly how A. baumannii became the notorious pathogen of today. Antibiotic resistance and virulence genes have been detected in strains from animals and environmental locations such as grass and soil. As such, A. baumannii is a One Health concern, which includes the health of humans, animals, and the environment. Thus, in order to truly combat the antibiotic resistance crisis, we need to understand the antibiotic resistance and virulence gene reservoirs of this pathogen under the One Health continuum.
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Affiliation(s)
- Ellen M. E. Sykes
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Valeria Mateo-Estrada
- Programa de Genómica Evolutiva, Centro de Ciencias Génomicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Raelene Engelberg
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Anna Muzaleva
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - George Zhanel
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Jeremy Dettman
- Ottawa Research and Development Centre (ORDC), Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada
| | - Julie Chapados
- Ottawa Research and Development Centre (ORDC), Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada
| | - Suzanne Gerdis
- Ottawa Research and Development Centre (ORDC), Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada
| | - Ömer Akineden
- Dairy Sciences, Institute of Veterinary Food Science, Justus-Liebig, University of Giessen, Giessen, Germany
| | - Izhar U. H. Khan
- Ottawa Research and Development Centre (ORDC), Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada
| | - Santiago Castillo-Ramírez
- Programa de Genómica Evolutiva, Centro de Ciencias Génomicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Ayush Kumar
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
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4
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Hamami E, Huo W, Neal K, Neisewander I, Geisinger E, Isberg RR. Identification of essential genes that support fitness of Acinetobacter baumannii efflux pump overproducers in the presence of fluoroquinolone. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.04.574119. [PMID: 38260615 PMCID: PMC10802289 DOI: 10.1101/2024.01.04.574119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Acinetobacter baumannii is a nosocomial pathogen often associated with multidrug resistance (MDR) infections. Fluoroquinolone resistance (FQR) due to drug target site mutations and elevated expression of RND drug transporters is common among clinical isolates. We describe here a CRISPRi platform that identifies hypomorphic mutations that preferentially altered drug sensitivity in RND pump overproducers. An sgRNA library against essential genes of A. baumannii was constructed with single and double nucleotide mutations that produced titratable knockdown efficiencies and introduced into multiple strain backgrounds. Other than nusG depletions, there were few candidates in the absence of drug treatment that showed lowered fitness specifically in strains overexpressing clinically relevant RND efflux pumps AdeAB, AdeIJK, or AdeFGH. In the presence of ciprofloxacin, the hypomorphs causing hypersensitivity were predicted to result in outer membrane dysfunction, to which the AdeFGH overproducer appeared particularly sensitive. Depletions of either the outer membrane assembly BAM complex, LOS biogenesis proteins, or Lpt proteins involved in LOS transport to the outer membrane caused drug hypersensitivity in at least two of the three pump overproducers. On the other hand, depletions of translation-associated proteins, as well as components of the proton-pumping ATP synthase pump resulted in fitness benefits for at least two pump-overproducing strains in the presence of the drug. Therefore, pump overproduction exacerbated stress caused by defective outer membrane integrity, while the efficacy of drug resistance in efflux overproducers was enhanced by slowed translation or defects in ATP synthesis linked to the control of proton movement across the bacterial membrane.
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Affiliation(s)
- Efrat Hamami
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
| | - Wenwen Huo
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
| | - Katherine Neal
- Department of Biochemistry, Curry College, Milton, MA, USA
| | - Isabelle Neisewander
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
| | - Edward Geisinger
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Ralph R Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 150 Harrison Ave., Boston, MA 02111, USA
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5
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Li L, Short FL, Hassan KA, Naidu V, Pokhrel A, Nagy SS, Prity FT, Shah BS, Afrin N, Baker S, Parkhill J, Cain AK, Paulsen IT. Systematic analyses identify modes of action of ten clinically relevant biocides and antibiotic antagonism in Acinetobacter baumannii. Nat Microbiol 2023; 8:1995-2005. [PMID: 37814070 DOI: 10.1038/s41564-023-01474-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 08/11/2023] [Indexed: 10/11/2023]
Abstract
Concerns exist that widespread use of antiseptic or disinfectant biocides could contribute to the emergence and spread of multidrug-resistant bacteria. To investigate this, we performed transposon-directed insertion-site sequencing (TraDIS) on the multidrug-resistant pathogen, Acinetobacter baumannii, exposed to a panel of ten structurally diverse and clinically relevant biocides. Multiple gene targets encoding cell envelope or cytoplasmic proteins involved in processes including fatty acid biogenesis, multidrug efflux, the tricarboxylic acid cycle, cell respiration and cell division, were identified to have effects on bacterial fitness upon biocide exposure, suggesting that these compounds may have intracellular targets in addition to their known effects on the cell envelope. As cell respiration genes are required for A. baumannii fitness in biocides, we confirmed that sub-inhibitory concentrations of the biocides that dissipate membrane potential can promote A. baumannii tolerance to antibiotics that act intracellularly. Our results support the concern that residual biocides might promote antibiotic resistance in pathogenic bacteria.
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Affiliation(s)
- Liping Li
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales, Australia
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Francesca L Short
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales, Australia
- Infection Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Karl A Hassan
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales, Australia
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, Australia
| | - Varsha Naidu
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales, Australia
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, Australia
| | - Alaska Pokhrel
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales, Australia
- Australian Institute for Microbiology and Infection (AIMI), University of Technology, Sydney, New South Wales, Australia
| | - Stephanie S Nagy
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Farzana T Prity
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales, Australia
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Bhumika S Shah
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales, Australia
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Nusrat Afrin
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Stephen Baker
- Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID), University of Cambridge, Cambridge, UK
| | - Julian Parkhill
- The Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Amy K Cain
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales, Australia.
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia.
| | - Ian T Paulsen
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales, Australia.
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia.
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Patil RS, Sharma S, Bhaskarwar AV, Nambiar S, Bhat NA, Koppolu MK, Bhukya H. TetR and OmpR family regulators in natural product biosynthesis and resistance. Proteins 2023. [PMID: 37874037 DOI: 10.1002/prot.26621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 08/30/2023] [Accepted: 10/06/2023] [Indexed: 10/25/2023]
Abstract
This article provides a comprehensive review and sequence-structure analysis of transcription regulator (TR) families, TetR and OmpR/PhoB, involved in specialized secondary metabolite (SSM) biosynthesis and resistance. Transcription regulation is a fundamental process, playing a crucial role in orchestrating gene expression to confer a survival advantage in response to frequent environmental stress conditions. This process, coupled with signal sensing, enables bacteria to respond to a diverse range of intra and extracellular signals. Thus, major bacterial signaling systems use a receptor domain to sense chemical stimuli along with an output domain responsible for transcription regulation through DNA-binding. Sensory and output domains on a single polypeptide chain (one component system, OCS) allow response to stimuli by allostery, that is, DNA-binding affinity modulation upon signal presence/absence. On the other hand, two component systems (TCSs) allow cross-talk between the sensory and output domains as they are disjoint and transmit information by phosphorelay to mount a response. In both cases, however, TRs play a central role. Biosynthesis of SSMs, which includes antibiotics, is heavily regulated by TRs as it diverts the cell's resources towards the production of these expendable compounds, which also have clinical applications. These TRs have evolved to relay information across specific signals and target genes, thus providing a rich source of unique mechanisms to explore towards addressing the rapid escalation in antimicrobial resistance (AMR). Here, we focus on the TetR and OmpR family TRs, which belong to OCS and TCS, respectively. These TR families are well-known examples of regulators in secondary metabolism and are ubiquitous across different bacteria, as they also participate in a myriad of cellular processes apart from SSM biosynthesis and resistance. As a result, these families exhibit higher sequence divergence, which is also evident from our bioinformatic analysis of 158 389 and 77 437 sequences from TetR and OmpR family TRs, respectively. The analysis of both sequence and structure allowed us to identify novel motifs in addition to the known motifs responsible for TR function and its structural integrity. Understanding the diverse mechanisms employed by these TRs is essential for unraveling the biosynthesis of SSMs. This can also help exploit their regulatory role in biosynthesis for significant pharmaceutical, agricultural, and industrial applications.
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Affiliation(s)
- Rachit S Patil
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Siddhant Sharma
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Aditya V Bhaskarwar
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Souparnika Nambiar
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Niharika A Bhat
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Mani Kanta Koppolu
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Hussain Bhukya
- Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
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7
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Nageeb WM, AlHarbi N, Alrehaili AA, Zakai SA, Elfadadny A, Hetta HF. Global genomic epidemiology of chromosomally mediated non-enzymatic carbapenem resistance in Acinetobacter baumannii: on the way to predict and modify resistance. Front Microbiol 2023; 14:1271733. [PMID: 37869654 PMCID: PMC10587612 DOI: 10.3389/fmicb.2023.1271733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 09/05/2023] [Indexed: 10/24/2023] Open
Abstract
Introduction Although carbapenemases are frequently reported in resistant A. baumannii clinical isolates, other chromosomally mediated elements of resistance that are considered essential are frequently underestimated. Having a wide substrate range, multidrug efflux pumps frequently underlie antibiotic treatment failure. Recognizing and exploiting variations in multidrug efflux pumps and penicillin-binding proteins (PBPs) is an essential approach in new antibiotic drug discovery and engineering to meet the growing challenge of multidrug-resistant Gram-negative bacteria. Methods A total of 980 whole genome sequences of A. baumannii were analyzed. Nucleotide sequences for the genes studied were queried against a custom database of FASTA sequences using the Bacterial and Viral Bioinformatics Resource Center (BV-BRC) system. The correlation between different variants and carbapenem Minimum Inhibitory Concentrations (MICs) was studied. PROVEAN and I-Mutant predictor suites were used to predict the effect of the studied amino acid substitutions on protein function and protein stability. Both PsiPred and FUpred were used for domain and secondary structure prediction. Phylogenetic reconstruction was performed using SANS serif and then visualized using iTOL and Phandango. Results Exhibiting the highest detection rate, AdeB codes for an important efflux-pump structural protein. T48V, T584I, and P660Q were important variants identified in the AdeB-predicted multidrug efflux transporter pore domains. These can act as probable targets for designing new efflux-pump inhibitors. Each of AdeC Q239L and AdeS D167N can also act as probable targets for restoring carbapenem susceptibility. Membrane proteins appear to have lower predictive potential than efflux pump-related changes. OprB and OprD changes show a greater effect than OmpA, OmpW, Omp33, and CarO changes on carbapenem susceptibility. Functional and statistical evidence make the variants T636A and S382N at PBP1a good markers for imipenem susceptibility and potential important drug targets that can modify imipenem resistance. In addition, PBP3_370, PBP1a_T636A, and PBP1a_S382N may act as potential drug targets that can be exploited to counteract imipenem resistance. Conclusion The study presents a comprehensive epidemiologic and statistical analysis of potential membrane proteins and efflux-pump variants related to carbapenem susceptibility in A. baumannii, shedding light on their clinical utility as diagnostic markers and treatment modification targets for more focused studies of candidate elements.
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Affiliation(s)
- Wedad M. Nageeb
- Department of Medical Microbiology and Immunology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| | - Nada AlHarbi
- Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
| | - Amani A. Alrehaili
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, Taif, Saudi Arabia
| | - Shadi A. Zakai
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmed Elfadadny
- Department of Animal Internal Medicine, Faculty of Veterinary Medicine, Damanhour University, Damanhour, El-Beheira, Egypt
| | - Helal F. Hetta
- Department of Medical Microbiology and Immunology, Faculty of Medicine, Assiut University, Assiut, Egypt
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8
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Leyn SA, Kent JE, Zlamal JE, Elane ML, Vercruysse M, Osterman AL. Two Classes of DNA Gyrase Inhibitors Elicit Distinct Evolutionary Trajectories Toward Resistance in Gram-Negative Pathogens. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.26.546596. [PMID: 37425702 PMCID: PMC10327078 DOI: 10.1101/2023.06.26.546596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Comprehensive knowledge of mechanisms driving the acquisition of antimicrobial resistance is essential for the development of new drugs with minimized resistibility. To gain this knowledge, we combine experimental evolution in a continuous culturing device, the morbidostat, with whole genome sequencing of evolving cultures followed by characterization of drug-resistant isolates. Here, this approach was used to assess evolutionary dynamics of resistance acquisition against DNA gyrase/topoisomerase TriBE inhibitor GP6 in Escherichia coli and Acinetobacter baumannii. The evolution of GP6 resistance in both species was driven by a combination of two classes of mutational events: (i) amino acid substitutions near the ATP-binding site of the GyrB subunit of the DNA gyrase target; and (ii) various mutations and genomic rearrangements leading to upregulation of efflux pumps, species-specific (AcrAB/TolC in E. coli and AdeIJK in A. baumannii) and shared by both species (MdtK). A comparison with the experimental evolution of resistance to ciprofloxacin (CIP), previously performed using the same workflow and strains, revealed fundamental differences between these two distinct classes of compounds. Most notable were non-overlapping spectra of target mutations and distinct evolutionary trajectories that, in the case of GP6, were dominated by upregulation of efflux machinery prior to (or even in lieu) of target modification. Most of efflux-driven GP6-resistant isolates of both species displayed a robust cross-resistance to CIP, while CIP-resistant clones showed no appreciable increase in GP6-resistance.
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Affiliation(s)
- Semen A. Leyn
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - James E. Kent
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Jaime E. Zlamal
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Marinela L. Elane
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Maarten Vercruysse
- Roche Pharma Research and Early Development, Immunology, Inflammation, and Infectious Diseases, Basel, Switzerland
| | - Andrei L. Osterman
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
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9
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Zhang S, Wang J, Ahn J. Advances in the Discovery of Efflux Pump Inhibitors as Novel Potentiators to Control Antimicrobial-Resistant Pathogens. Antibiotics (Basel) 2023; 12:1417. [PMID: 37760714 PMCID: PMC10525980 DOI: 10.3390/antibiotics12091417] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 09/04/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
The excessive use of antibiotics has led to the emergence of multidrug-resistant (MDR) pathogens in clinical settings and food-producing animals, posing significant challenges to clinical management and food control. Over the past few decades, the discovery of antimicrobials has slowed down, leading to a lack of treatment options for clinical infectious diseases and foodborne illnesses. Given the increasing prevalence of antibiotic resistance and the limited availability of effective antibiotics, the discovery of novel antibiotic potentiators may prove useful for the treatment of bacterial infections. The application of antibiotics combined with antibiotic potentiators has demonstrated successful outcomes in bench-scale experiments and clinical settings. For instance, the use of efflux pump inhibitors (EPIs) in combination with antibiotics showed effective inhibition of MDR pathogens. Thus, this review aims to enable the possibility of using novel EPIs as potential adjuvants to effectively control MDR pathogens. Specifically, it provides a comprehensive summary of the advances in novel EPI discovery and the underlying mechanisms that restore antimicrobial activity. In addition, we also characterize plant-derived EPIs as novel potentiators. This review provides insights into current challenges and potential strategies for future advancements in fighting antibiotic resistance.
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Affiliation(s)
- Song Zhang
- Department of Biomedical Science, Kangwon National University, Chuncheon 24341, Republic of Korea;
| | - Jun Wang
- College of Food Science and Engineering, Qingdao Agricultural University, Qingdao 266109, China
| | - Juhee Ahn
- Department of Biomedical Science, Kangwon National University, Chuncheon 24341, Republic of Korea;
- Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon 24341, Republic of Korea
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10
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Ambrose SJ, Hamidian M, Hall RM. The extensively antibiotic resistant ST111 Acinetobacter baumannii isolate RBH2 carries an extensive mobile element complement of plasmids, transposons and insertion sequences. Plasmid 2023; 128:102707. [PMID: 37678515 DOI: 10.1016/j.plasmid.2023.102707] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 08/31/2023] [Accepted: 09/04/2023] [Indexed: 09/09/2023]
Abstract
The complete genome of RBH2, a sporadic, carbapenem resistant ST111 Acinetobacter baumannii isolate from Brisbane, Australia was determined and analysed. RBH2 is extensively resistant and the chromosome includes two transposons carrying antibiotic resistance genes, AbaR4 (oxa23 in Tn2006) and Tn7::Tn2006 (dfrA1, sat2, aadA1, oxa23). The chromosome also includes two copies of Tn6175, a transposon carrying putative copper resistance genes, and 1-17 copies of six different insertion sequences. RBH2 has six plasmids ranging in size from 6 kb - 141 kb, four carrying antibiotic resistance genes. Plasmids pRBH2-1 (aadB) and pRBH2-2 (aphA6 in TnaphA6) were found to be essentially identical to known plasmids pRAY*-v1 and pS21-1, respectively. The largest plasmids, pRBH2-5 (oxa23 in AbaR4) and pRBH2-6 (oxa23 in AbaR4::ISAba11 and sul2, tet(B), strA and strB in Tn6172) have known transfer-proficient relatives. pRBH2-5, an RP-T1 (RepAci6) plasmid, also carries a different putative copper resistance transposon related to Tn6177 found in pS21-2. The backbone of pRBH2-5 is related to those of previously described RepAci6 plasmids pAb-G7-2 and pA85-3 but has some distinctive features. Three different RepAci6 backbone types were distinguished, Type 1 (pAb-G7-2), Type 2 (pA85-3) and Type 3 (pRBH2-5 and pS21-2). pRBH2-6 is closely related to pAB3 and their backbones differ by only 5 SNPs. Plasmids pRBH2-3 and pRBH2-4 do not carry antibiotic resistance genes. pRBH2-3 does not include an identifiable rep gene and is a novel plasmid type. pRBH2-4 is of the R3-T3 type and includes segments of the larger pABTJ2 that heads this group. Other ST111 genomes carry different plasmids.
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Affiliation(s)
- Stephanie J Ambrose
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
| | - Mehrad Hamidian
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia; Australian Institute for Microbiology and Infection, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Ruth M Hall
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
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11
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Wang H, Wang X, Tang Q, Wang L, Mei C, Shao Y, Xu Y, Lu Z, Zhong W. Regulation Mechanism of Nicotine Catabolism in Sphingomonas melonis TY by a Dual Role Transcriptional Regulator NdpR. Appl Environ Microbiol 2023; 89:e0032423. [PMID: 37071026 PMCID: PMC10231238 DOI: 10.1128/aem.00324-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 03/25/2023] [Indexed: 04/19/2023] Open
Abstract
A gene cluster ndp, responsible for nicotine degradation via a variant of the pyridine and pyrrolidine pathways, was previously identified in Sphingomonas melonis TY, but the regulation mechanism remains unknown. The gene ndpR within the cluster was predicted to encode a TetR family transcriptional regulator. Deletion of ndpR resulted in a notably shorter lag phase, higher maximum turbidity, and faster substrate degradation when cultivated in the presence of nicotine. Real-time quantitative PCR and promoter activity analysis in wild-type TY and TYΔndpR strains revealed that genes in the ndp cluster were negatively regulated by NdpR. However, complementation of ndpR to TYΔndpR did not restore transcription repression, but, instead, the complemented strain showed better growth than TYΔndpR. Promoter activity analysis indicates that NdpR also functions as an activator in the transcription regulation of ndpHFEGD. Further analysis through electrophoretic mobility shift assay and DNase I footprinting assay revealed that NdpR binds five DNA sequences within ndp and that NdpR has no autoregulation. These binding motifs overlap with the -35 or -10 box or are located distal upstream of the corresponding transcriptional start site. Multiple sequence alignment of these five NdpR-binding DNA sequences found a conserved motif, with two of the binding sequences being partially palindromic. 2,5-Dihydroxypyridine acted as a ligand of NdpR, preventing NdpR from binding to the promoter region of ndpASAL, ndpTB, and ndpHFEGD. This study revealed that NdpR binds to three promoters in the ndp cluster and is a dual-role transcriptional regulator in nicotine metabolism. IMPORTANCE Gene regulation is critical for microorganisms in the environment in which they may encounter various kinds of organic pollutants. Our study revealed that transcription of ndpASAL, ndpTB, and ndpHFEGD is negatively regulated by NdpR, and NdpR also exhibits a positive regulatory effect on PndpHFEGD. Furthermore, 2,5-dihydroxypyridine was identified as the effector molecular for NdpR and can both prevent the binding of free NdpR to the promoter and release NdpR from the promoters, which is different from previously reported NicR2. Additionally, NdpR was found to have both negative and positive transcription regulatory effects on the same target, PndpHFEGD, while only one binding site was identified, which is notably different from the previously reported TetR family regulators. Moreover, NdpR was revealed to be a global transcriptional regulator. This study provides new insight into the complex gene expression regulation of the TetR family.
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Affiliation(s)
- Haixia Wang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Xiaoyu Wang
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Qi Tang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Lvjing Wang
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Chengyu Mei
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Yunhai Shao
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Ying Xu
- Department of Microbial Sciences, State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Zhenmei Lu
- MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Weihong Zhong
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
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12
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De Gaetano GV, Lentini G, Famà A, Coppolino F, Beninati C. Antimicrobial Resistance: Two-Component Regulatory Systems and Multidrug Efflux Pumps. Antibiotics (Basel) 2023; 12:965. [PMID: 37370284 DOI: 10.3390/antibiotics12060965] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 05/22/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
The number of multidrug-resistant bacteria is rapidly spreading worldwide. Among the various mechanisms determining resistance to antimicrobial agents, multidrug efflux pumps play a noteworthy role because they export extraneous and noxious substrates from the inside to the outside environment of the bacterial cell contributing to multidrug resistance (MDR) and, consequently, to the failure of anti-infective therapies. The expression of multidrug efflux pumps can be under the control of transcriptional regulators and two-component systems (TCS). TCS are a major mechanism by which microorganisms sense and reply to external and/or intramembrane stimuli by coordinating the expression of genes involved not only in pathogenic pathways but also in antibiotic resistance. In this review, we describe the influence of TCS on multidrug efflux pump expression and activity in some Gram-negative and Gram-positive bacteria. Taking into account the strict correlation between TCS and multidrug efflux pumps, the development of drugs targeting TCS, alone or together with already discovered efflux pump inhibitors, may represent a beneficial strategy to contribute to the fight against growing antibiotic resistance.
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Affiliation(s)
| | - Germana Lentini
- Department of Human Pathology, University of Messina, 98124 Messina, Italy
| | - Agata Famà
- Department of Human Pathology, University of Messina, 98124 Messina, Italy
| | - Francesco Coppolino
- Department of Biomedical, Dental and Imaging Sciences, University of Messina, 98124 Messina, Italy
| | - Concetta Beninati
- Department of Human Pathology, University of Messina, 98124 Messina, Italy
- Scylla Biotech Srl, 98124 Messina, Italy
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13
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Sun C, Yu Y, Hua X. Resistance mechanisms of tigecycline in Acinetobacter baumannii. Front Cell Infect Microbiol 2023; 13:1141490. [PMID: 37228666 PMCID: PMC10203620 DOI: 10.3389/fcimb.2023.1141490] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 04/14/2023] [Indexed: 05/27/2023] Open
Abstract
Acinetobacter baumannii is widely distributed in nature and in hospital settings and is a common pathogen causing various infectious diseases. Currently, the drug resistance rate of A. baumannii has been persistently high, showing a worryingly high resistance rate to various antibiotics commonly used in clinical practice, which greatly limits antibiotic treatment options. Tigecycline and polymyxins show rapid and effective bactericidal activity against CRAB, and they are both widely considered to be the last clinical line of defense against multidrug resistant A. baumannii. This review focuses with interest on the mechanisms of tigecycline resistance in A. baumannii. With the explosive increase in the incidence of tigecycline-resistant A. baumannii, controlling and treating such resistance events has been considered a global challenge. Accordingly, there is a need to systematically investigate the mechanisms of tigecycline resistance in A. baumannii. Currently, the resistance mechanism of A. baumannii to tigecycline is complex and not completely clear. This article reviews the proposed resistance mechanisms of A. baumannii to tigecycline, with a view to providing references for the rational clinical application of tigecycline and the development of new candidate antibiotics.
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Affiliation(s)
- Chunli Sun
- Zhejiang University-University of Edinburgh (ZJU-UoE) Institute, Zhejiang University, Haining, Zhejiang, China
| | - Yunsong Yu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
- Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaoting Hua
- Zhejiang University-University of Edinburgh (ZJU-UoE) Institute, Zhejiang University, Haining, Zhejiang, China
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China
- Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
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14
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Castanheira M, Mendes RE, Gales AC. Global Epidemiology and Mechanisms of Resistance of Acinetobacter baumannii-calcoaceticus Complex. Clin Infect Dis 2023; 76:S166-S178. [PMID: 37125466 PMCID: PMC10150277 DOI: 10.1093/cid/ciad109] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
Acinetobacter baumannii-calcoaceticus complex is the most commonly identified species in the genus Acinetobacter and it accounts for a large percentage of nosocomial infections, including bacteremia, pneumonia, and infections of the skin and urinary tract. A few key clones of A. baumannii-calcoaceticus are currently responsible for the dissemination of these organisms worldwide. Unfortunately, multidrug resistance is a common trait among these clones due to their unrivalled adaptive nature. A. baumannii-calcoaceticus isolates can accumulate resistance traits by a plethora of mechanisms, including horizontal gene transfer, natural transformation, acquisition of mutations, and mobilization of genetic elements that modulate expression of intrinsic and acquired genes.
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Affiliation(s)
| | | | - Ana C Gales
- Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
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15
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Zhao Y, Wei HM, Yuan JL, Xu L, Sun JQ. A comprehensive genomic analysis provides insights on the high environmental adaptability of Acinetobacter strains. Front Microbiol 2023; 14:1177951. [PMID: 37138596 PMCID: PMC10149724 DOI: 10.3389/fmicb.2023.1177951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 03/28/2023] [Indexed: 05/05/2023] Open
Abstract
Acinetobacter is ubiquitous, and it has a high species diversity and a complex evolutionary pattern. To elucidate the mechanism of its high ability to adapt to various environment, 312 genomes of Acinetobacter strains were analyzed using the phylogenomic and comparative genomics methods. It was revealed that the Acinetobacter genus has an open pan-genome and strong genome plasticity. The pan-genome consists of 47,500 genes, with 818 shared by all the genomes of Acinetobacter, while 22,291 are unique genes. Although Acinetobacter strains do not have a complete glycolytic pathway to directly utilize glucose as carbon source, most of them harbored the n-alkane-degrading genes alkB/alkM (97.1% of tested strains) and almA (96.7% of tested strains), which were responsible for medium-and long-chain n-alkane terminal oxidation reaction, respectively. Most Acinetobacter strains also have catA (93.3% of tested strains) and benAB (92.0% of tested strains) genes that can degrade the aromatic compounds catechol and benzoic acid, respectively. These abilities enable the Acinetobacter strains to easily obtain carbon and energy sources from their environment for survival. The Acinetobacter strains can manage osmotic pressure by accumulating potassium and compatible solutes, including betaine, mannitol, trehalose, glutamic acid, and proline. They respond to oxidative stress by synthesizing superoxide dismutase, catalase, disulfide isomerase, and methionine sulfoxide reductase that repair the damage caused by reactive oxygen species. In addition, most Acinetobacter strains contain many efflux pump genes and resistance genes to manage antibiotic stress and can synthesize a variety of secondary metabolites, including arylpolyene, β-lactone and siderophores among others, to adapt to their environment. These genes enable Acinetobacter strains to survive extreme stresses. The genome of each Acinetobacter strain contained different numbers of prophages (0-12) and genomic islands (GIs) (6-70), and genes related to antibiotic resistance were found in the GIs. The phylogenetic analysis revealed that the alkM and almA genes have a similar evolutionary position with the core genome, indicating that they may have been acquired by vertical gene transfer from their ancestor, while catA, benA, benB and the antibiotic resistance genes could have been acquired by horizontal gene transfer from the other organisms.
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Affiliation(s)
- Yang Zhao
- Lab for Microbial Resources, School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Hua-Mei Wei
- Lab for Microbial Resources, School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Jia-Li Yuan
- Lab for Microbial Resources, School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Lian Xu
- Jiangsu Key Lab for Organic Solid Waste Utilization, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Ji-Quan Sun
- Lab for Microbial Resources, School of Ecology and Environment, Inner Mongolia University, Hohhot, China
- *Correspondence: Ji-Quan Sun,
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16
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Naidu V, Bartczak A, Brzoska AJ, Lewis P, Eijkelkamp BA, Paulsen IT, Elbourne LDH, Hassan KA. Evolution of RND efflux pumps in the development of a successful pathogen. Drug Resist Updat 2023; 66:100911. [PMID: 36592567 DOI: 10.1016/j.drup.2022.100911] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 12/13/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022]
Abstract
AIMS This study examined the origins and evolution of the AdeABC, AdeFGH and AdeIJK efflux pumps in the Acinetobacter genus, including human and animal pathogens and species from non-clinical environments. METHODS Comparative genome analyses were performed using the reference sequences for 70 Acinetobacter species to identify putative orthologs of AdeABC, AdeFGH and AdeIJK and their regulators. Sequence similarities and the genomic locations of coding sequences were correlated with phylogeny to infer modes of evolution. Intraspecies variation was assessed in species of interest using up to 236 complete genome sequences. Mutants overproducing adeIJK in A. baylyi were examined to identify regulators of this system in a non A. baumannii species. RESULTS The results indicate that adeIJK has been a stable part of Acinetobacter genomes since the genesis of this genus, whereas adeABC and adeFGH were carried by less than half of the species, but showed some lineage specificity. The organisation and local genetic contexts of adeABC loci were particularly variable to the sub-species level, suggesting frequent recombination. Cognate regulatory systems were almost always found in the genomes of species encoding pumps. Mutations in adeN, which encodes a repressor of adeIJK, were selected by antibiotic exposure in A. baylyi, similar to previous findings in pathogenic lineages. CONCLUSIONS The multidrug efflux capacity of clinical Acinetobacter strains stems from accessory and core genetic features. AdeIJK is likely to have ancient core function(s) that have promoted its maintenance, whereas recent antibiotic use may be driving the evolution of the AdeABC pump.
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Affiliation(s)
- Varsha Naidu
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW, Australia; ARC Centre of Excellence in Synthetic Biology, Macquarie University, North Ryde, NSW, Australia
| | - Amelia Bartczak
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW, Australia
| | - Anthony J Brzoska
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW, Australia
| | - Peter Lewis
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW, Australia; Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia; Hunter Biological Solutions, Newcastle, NSW, Australia
| | - Bart A Eijkelkamp
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Ian T Paulsen
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, North Ryde, NSW, Australia; School of Natural Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Liam D H Elbourne
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, North Ryde, NSW, Australia; School of Natural Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Karl A Hassan
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW, Australia; ARC Centre of Excellence in Synthetic Biology, Macquarie University, North Ryde, NSW, Australia.
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Schuster D, Axtmann K, Holstein N, Felder C, Voigt A, Färber H, Ciorba P, Szekat C, Schallenberg A, Böckmann M, Zarfl C, Neidhöfer C, Smalla K, Exner M, Bierbaum G. Antibiotic concentrations in raw hospital wastewater surpass minimal selective and minimum inhibitory concentrations of resistant Acinetobacter baylyi strains. Environ Microbiol 2022; 24:5721-5733. [PMID: 36094736 DOI: 10.1111/1462-2920.16206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 09/10/2022] [Indexed: 01/12/2023]
Abstract
Antibiotics are essential for modern medicine, they are employed frequently in hospitals and, therefore, present in hospital wastewater. Even in concentrations, that are lower than the minimum inhibitory concentrations (MICs) of susceptible bacteria, antibiotics may exert an influence and select resistant bacteria, if they exceed the MSCs (minimal selective concentrations) of resistant strains. Here, we compare the MSCs of fluorescently labelled Acinetobacter baylyi strains harboring spontaneous resistance mutations or a resistance plasmid with antibiotic concentrations determined in hospital wastewater. Low MSCs in the μg/L range were measured for the quinolone ciprofloxacin (17 μg/L) and for the carbapenem meropenem (30 μg/L). A 24 h continuous analysis of hospital wastewater showed daily fluctuations of the concentrations of these antibiotics with distinctive peaks at 7-8 p.m. and 5-6 a.m. The meropenem concentrations were always above the MSC and MIC values of A. baylyi. In addition, the ciprofloxacin concentrations were in the range of the lowest MSC for about half the time. These results explain the abundance of strains with meropenem and ciprofloxacin resistance in hospital wastewater and drains.
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Affiliation(s)
- Dominik Schuster
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Katharina Axtmann
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Niklas Holstein
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Carsten Felder
- Institute for Hygiene and Public Health, University Hospital Bonn, Bonn, Germany
| | - Alex Voigt
- Institute for Hygiene and Public Health, University Hospital Bonn, Bonn, Germany
| | - Harald Färber
- Institute for Hygiene and Public Health, University Hospital Bonn, Bonn, Germany
| | - Patrick Ciorba
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Christiane Szekat
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Anna Schallenberg
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Matthias Böckmann
- Environmental Systems Analysis, Eberhard Karls University of Tuebingen, Tuebingen, Germany
| | - Christiane Zarfl
- Environmental Systems Analysis, Eberhard Karls University of Tuebingen, Tuebingen, Germany
| | - Claudio Neidhöfer
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Kornelia Smalla
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany
| | - Martin Exner
- Institute for Hygiene and Public Health, University Hospital Bonn, Bonn, Germany
| | - Gabriele Bierbaum
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
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18
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Meyer C, Lucaβen K, Gerson S, Xanthopoulou K, Wille T, Seifert H, Higgins PG. Contribution of RND-Type Efflux Pumps in Reduced Susceptibility to Biocides in Acinetobacter baumannii. Antibiotics (Basel) 2022; 11:1635. [PMID: 36421279 PMCID: PMC9686468 DOI: 10.3390/antibiotics11111635] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/11/2022] [Accepted: 11/15/2022] [Indexed: 07/30/2023] Open
Abstract
Bacterial efflux pumps are among the key mechanisms of resistance against antibiotics and biocides. We investigated whether differential expression levels of the RND-type efflux pumps AdeABC and AdeIJK impacted the susceptibility to commonly used biocides in multidrug-resistant Acinetobacter baumannii. Susceptibility testing and time-kill assays of defined laboratory and clinical A. baumannii strains with different levels of efflux pump expression were performed after exposure to the biocides benzalkonium chloride, chlorhexidine digluconate, ethanol, glucoprotamin, octenidine dihydrochloride, and triclosan. While the impact of efflux pump expression on susceptibility to the biocides was limited, noticeable differences were found in kill curves, where AdeABC expression correlated with greater survival after exposure to benzalkonium chloride, chlorhexidine digluconate, glucoprotamin, and octenidine dihydrochloride. AdeABC expression levels did not impact kill kinetics with ethanol nor triclosan. In conclusion, these data indicate that the overexpression of the RND-type efflux pumps AdeABC and AdeIJK contributes to the survival of A. baumannii when exposed to residual concentrations of biocides.
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Affiliation(s)
- Christina Meyer
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50935 Cologne, Germany
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, 50935 Cologne, Germany
| | - Kai Lucaβen
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50935 Cologne, Germany
| | - Stefanie Gerson
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50935 Cologne, Germany
| | - Kyriaki Xanthopoulou
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50935 Cologne, Germany
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, 50935 Cologne, Germany
| | - Thorsten Wille
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50935 Cologne, Germany
| | - Harald Seifert
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50935 Cologne, Germany
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, 50935 Cologne, Germany
| | - Paul G. Higgins
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50935 Cologne, Germany
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, 50935 Cologne, Germany
- Center for Molecular Medicine Cologne, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50935 Cologne, Germany
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Dehbanipour R, Ghalavand Z. Acinetobacter baumannii: Pathogenesis, virulence factors, novel therapeutic options and mechanisms of resistance to antimicrobial agents with emphasis on tigecycline. J Clin Pharm Ther 2022; 47:1875-1884. [PMID: 36200470 DOI: 10.1111/jcpt.13787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 09/13/2022] [Accepted: 09/18/2022] [Indexed: 11/30/2022]
Abstract
WHAT IS KNOWN AND OBJECTIVE Acinetobacter baumannii is one of the most important nosocomial pathogens with the ability to cause infections such as meningitis, pneumonia, urinary tract, septicaemia and wound infections. A wide range of virulence factors are responsible for pathogenesis and high mortality of A. baumannii including outer membrane proteins, lipopolysaccharide, capsule, phospholipase, nutrient- acquisition systems, efflux pumps, protein secretion systems, quarom sensing and biofilm production. These virulence factors contribute in pathogen survival in stressful conditions and antimicrobial resistance. COMMENT According to the World Health Organization (WHO), A. baumannii is one of the most resistant pathogens of ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, A. baumannii, Pseudomonas aeruginosa and Enterobacter spp.). In recent years, resistance to a wide range of antibiotics in A. baumannii has significantly increased and the high emergence of extensively drug resistant (XDR) isolates is challenging. Among therapeutic antibiotics, resistance to tigecycline as a last resort antibiotic has become a global concern. Several mechanisms are involved in tigecycline resistance, the most important of which is RND (Resistance-Nodulation-Division) family efflux pumps overexpression. The development of new therapeutic strategies to confront A. baumannii infections has been very promising in recent years. WHAT IS NEW AND CONCLUSION In the present review we highlight microbiological and virulence traits in A. baumannii and peruse the tigecycline resistance mechanisms and novel therapeutic options. Among the novel therapeutic strategies we focus on combination therapy, drug repurposing, novel antibiotics, bacteriophage therapy, antimicrobial peptides (AMPs), human monoclonal antibodies (Hu-mAbs), nanoparticles and gene editing.
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Affiliation(s)
- Razieh Dehbanipour
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Zohreh Ghalavand
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Zgurskaya HI, Adamiak JW, Leus IV. Making sense of drug-efflux transporters in the physiological environment. Curr Opin Microbiol 2022; 69:102179. [PMID: 35882103 PMCID: PMC9942525 DOI: 10.1016/j.mib.2022.102179] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 06/23/2022] [Accepted: 06/24/2022] [Indexed: 02/06/2023]
Abstract
Bacterial drug-efflux transporters act synergistically with diffusion barriers of cellular membranes and other resistance mechanisms to protect cells from antibiotics and toxic metabolites. Their critical roles in clinical antibiotic and multidrug resistance are well established. In addition, a large body of evidence has been accumulated in support of their important contributions to bacterial growth and proliferation during infections. However, how these diverse functions of drug transporters are integrated at the level of bacterial cell physiology remains unclear. This opinion briefly summarizes the current understanding of substrate specificities and physiological roles of drug-efflux pumps from Resistance-Nodulation-Division (RND) superfamily of proteins in two ESKAPE pathogens Pseudomonas aeruginosa and Acinetobacter baumannii. Based on the analysis of phenotypic and transcriptomic studies in vitro and in vivo, we propose that RND pumps of Gram-negative bacteria fall into three categories: constitutively expressed, regulated, and silent. These three categories of efflux pumps participate in different physiological programs, which are not involved in the central metabolism and bacterial growth.
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Affiliation(s)
- Helen I Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73072, USA.
| | - Justyna W Adamiak
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73072, USA
| | - Inga V Leus
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73072, USA
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Ghalavand Z, Eslami G, Hashemi A, Sadredinamin M, Yousefi N, Dehbanipour R. Characterization of Sequence Types and Mechanisms of Resistance to Tigecycline Among Acinetobacter baumannii Isolated from Children. Curr Microbiol 2022; 79:285. [PMID: 35947200 DOI: 10.1007/s00284-022-02976-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 07/15/2022] [Indexed: 11/26/2022]
Abstract
The present study aimed to investigate the mechanisms of resistance to tigecycline and to determine sequence types of Acinetobacter baumannii isolates recovered from children, using the Multilocus Sequence Typing (MLST). A total of 74 A. baumannii isolates were recovered from patients at one of the children's hospital in Tehran, Iran. Antimicrobial susceptibility testing of the isolates was performed for different classes of antibiotics and minimum inhibitory concentrations of colistin and tigecycline were determined using broth microdilution method and E-test strips, respectively. The presence of ISAba1, AbaR, tet(39), and tetX and the expressions of adeB, adeG, and adeJ efflux pump genes were measured using Polymerase Chain Reaction (PCR) and quantitative real-time PCR (RT-PCR), respectively. The diversity of mutations across the regulatory genes of RND efflux pumps (adeRS, adeL, and adeN) and trm gene were determined using their PCR amplification and DNA sequencing in tigecycline-resistant isolates. In addition, STs of tigecycline-resistant isolates were determined using MLST method. Three A. baumannii isolates were resistant to tigecycline. Several amino acid substitutions were identified in AdeRS, AdeN, and Trm but no alteration was found in AdeL. Nevertheless, adeB, adeG, and adeJ overexpression were observed in 1, 2, and 1 isolates, respectively. The tigecycline-resistant isolates belonged to ST1720 and ST2285. This is the first study reporting on ST2285 in A. baumannii populations. Among 74 isolates, two tigecycline susceptible isolates carried tet(39) gene but no tetX gene was detected. We concluded that mutations in regulatory genes of RND efflux pumps and the trm gene may play some important role in A. baumannii resistance to tigecycline.
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Affiliation(s)
- Zohreh Ghalavand
- Infectious Diseases and Tropical Medicine Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Gita Eslami
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ali Hashemi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mehrzad Sadredinamin
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Neda Yousefi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Razieh Dehbanipour
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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22
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Sawant AR, Pagal S, Amar AK, Panda L, Devi C S, Shashikala P, Kanungo R, Prashanth K. Coexistence of blaNDM-1, blaOXA-51, blaOXA-23 and armA in conjunction with novel mutations detected in RND efflux pump regulators in tigecycline resistant clinical isolates of Acinetobacter baumannii. Pathog Dis 2022; 80:6608938. [PMID: 35704614 DOI: 10.1093/femspd/ftac020] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 05/12/2022] [Accepted: 06/13/2022] [Indexed: 11/12/2022] Open
Abstract
This study has investigated a total of 51 A. baumannii isolates for the prevalence of resistant determinants in tigecycline susceptible and non-susceptible clinical isolates of A. baumannii. Antimicrobial susceptibility testing revealed 74% of isolates were tigecycline resistant. Mutations in RND-efflux pump regulatory genes and the expression of efflux pump genes were measured in tigecycline resistant isolates. There was a strong co-relation between the blaNDM-1 and armA wherein majority of the isolates that are positive for blaNDM-1 have also harbored armA. Compared with TSAB (tigecycline susceptible A. baumannii), TNAB (tigecycline non-susceptible A. baumannii) isolates show increased distribution of blaNDM-1 (p = 0.048), blaIMP-1 (p<0.0001) and blaOXA-51 (p = 0.0029) carbapenemase genes. The variants of RND-efflux pump regulatory genes due to amino-acid mutations in adeS (F12S, K84E, W61R, N268H and Q299R) and adeL (G21R and Q262R) were identified in tigecycline resistant isolates as well as ISAba1 mediated disruption of adeN were observed causing overexpression of adeIJK efflux pump. Additionally, mutations in adeRS were also associated with increased expression of adeABC efflux pump. Besides, TNAB isolates showed significantly (p<0.0001) higher ability of biofilm formation as compared to TSAB isolates. The tigecycline resistance due to mutations in contemporary A. baumannii isolates having a higher ability to form biofilm may pose therapeutic difficulties.
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Affiliation(s)
- Ajit Ramesh Sawant
- Department of Biotechnology, School of Life Sciences, Pondicherry University, Pondicherry, India
| | - Sudhakar Pagal
- Department of Biotechnology, School of Life Sciences, Pondicherry University, Pondicherry, India
| | - Ashutosh Kumar Amar
- Department of Biotechnology, School of Life Sciences, Pondicherry University, Pondicherry, India
| | - Lipsa Panda
- Department of Biotechnology, School of Life Sciences, Pondicherry University, Pondicherry, India
| | - Sheela Devi C
- Department of Clinical Microbiology, Pondicherry Institute of Medical Sciences (PIMS), Pondicherry, India
| | - P Shashikala
- Department of Clinical Microbiology, Pondicherry Institute of Medical Sciences (PIMS), Pondicherry, India
| | - Reba Kanungo
- Department of Clinical Microbiology, Pondicherry Institute of Medical Sciences (PIMS), Pondicherry, India
| | - K Prashanth
- Department of Biotechnology, School of Life Sciences, Pondicherry University, Pondicherry, India
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López-Siles M, McConnell MJ, Martín-Galiano AJ. Identification of Promoter Region Markers Associated With Altered Expression of Resistance-Nodulation-Division Antibiotic Efflux Pumps in Acinetobacter baumannii. Front Microbiol 2022; 13:869208. [PMID: 35663863 PMCID: PMC9161033 DOI: 10.3389/fmicb.2022.869208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/27/2022] [Indexed: 11/13/2022] Open
Abstract
Genetic alterations leading to the constitutive upregulation of specific efflux pumps contribute to antibacterial resistance in multidrug resistant bacteria. The identification of such resistance markers remains one of the most challenging tasks of genome-level resistance predictors. In this study, 487 non-redundant genetic events were identified in upstream zones of three operons coding for resistance-nodulation-division (RND) efflux pumps of 4,130 Acinetobacter baumannii isolates. These events included insertion sequences, small indels, and single nucleotide polymorphisms. In some cases, alterations explicitly modified the expression motifs described for these operons, such as the promoter boxes, operators, and Shine-Dalgarno sequences. In addition, changes in DNA curvature and mRNA secondary structures, which are structural elements that regulate expression, were also calculated. According to their influence on RND upregulation, the catalog of upstream modifications were associated with “experimentally verified,” “presumed,” and “probably irrelevant” degrees of certainty. For experimental verification, DNA of upstream sequences independently carrying selected markers, three for each RND operon, were fused to a luciferase reporter plasmid system. Five out of the nine selected markers tested showed significant increases in expression with respect to the wild-type sequence control. In particular, a 25-fold expression increase was observed with the ISAba1 insertion sequence upstream the adeABC pump. Next, overexpression of each of the three multi-specific RND pumps was linked to their respective antibacterial substrates by a deep A. baumannii literature screen. Consequently, a data flow framework was then developed to link genomic upregulatory RND determinants to potential antibiotic resistance. Assignment of potential increases in minimal inhibitory concentrations at the “experimentally verified” level was permitted for 42 isolates to 7–8 unrelated antibacterial agents including tigecycline, which is overlooked by conventional resistome predictors. Thus, our protocol may represent a time-saving filter step prior to laborious confirmation experiments for efflux-driven resistance. Altogether, a computational-experimental pipeline containing all components required for identifying the upstream regulatory resistome is proposed. This schema may provide the foundational stone for the elaboration of tools approaching antibiotic efflux that complement routine resistome predictors for preventing antimicrobial therapy failure against difficult-to-threat bacteria.
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Synergistic Inhibitory Effect of Polymyxin B in Combination with Ceftazidime against Robust Biofilm Formed by Acinetobacter baumannii with Genetic Deficiency in AbaI/AbaR Quorum Sensing. Microbiol Spectr 2022; 10:e0176821. [PMID: 35196792 PMCID: PMC8865539 DOI: 10.1128/spectrum.01768-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Carbapenem resistance of Acinetobacter baumannii poses challenges to public health. Biofilm contributes to the persistence of A. baumannii cells. This study was designed to investigate the genetic relationships among carbapenem resistance, polymyxin resistance, multidrug resistance, biofilm formation, and surface-associated motility and evaluate the antibiofilm effect of polymyxin in combination with other antibiotics. A total of 103 clinical A. baumannii strains were used to determine antibiotic susceptibility, biofilm formation capacity, and motility. Enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting was used to determine the genetic variation among strains. The distribution of 17 genes related to the resistance-nodulation-cell division (RND)-type efflux, autoinducer-receptor (AbaI/AbaR) quorum sensing, oxacillinases (OXA)-23, and insertion sequence of ISAba1 element was investigated. The representative strains were chosen to evaluate the gene transcription and the antibiofilm activity by polymyxin B (PB) in combination with merapenem, levofloxacin, and ceftazidime, respectively. ERIC-PCR-dependent fingerprints were found to be associated with carbapenem resistance and multidrug resistance. The presence of blaOXA-23 was found to correlate with genes involved in ISAba1 insertion, AbaI/AbaR quorum sensing, and AdeABC efflux. Carbapenem resistance was observed to be negatively correlated with biofilm formation and positively correlated with motility. PB in combination with ceftazidime displayed a synergistic antibiofilm effect against robust biofilm formed by an A. baumannii strain with deficiency in AbaI/AbaR quorum sensing. Our results not only clarify the genetic correlation among carbapenem resistance, biofilm formation, and pathogenicity in a certain level but also provide a theoretical basis for clinical applications of polymyxin-based combination of antibiotics in antibiofilm therapy. IMPORTANCE Deeper explorations of molecular correlation among antibiotic resistance, biofilm formation, and pathogenicity could provide novel insights that would facilitate the development of therapeutics and prevention against A. baumannii biofilm-related infections. The major finding that polymyxin B in combination with ceftazidime displayed a synergistic antibiofilm effect against robust biofilm formed by an A. baumannii strain with genetic deficiency in AbaI/AbaR quorum sensing further provides a theoretical basis for clinical applications of antibiotics in combination with quorum quenching in antibiofilm therapy.
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Rescuing Tetracycline Class Antibiotics for the Treatment of Multidrug-Resistant Acinetobacter baumannii Pulmonary Infection. mBio 2022; 13:e0351721. [PMID: 35012353 PMCID: PMC8749419 DOI: 10.1128/mbio.03517-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Acinetobacter baumannii causes high mortality in ventilator-associated pneumonia patients, and antibiotic treatment is compromised by multidrug-resistant strains resistant to β-lactams, carbapenems, cephalosporins, polymyxins, and tetracyclines. Among COVID-19 patients receiving ventilator support, a multidrug-resistant A. baumannii secondary infection is associated with a 2-fold increase in mortality. Here, we investigated the use of the 8-hydroxyquinoline ionophore PBT2 to break the resistance of A. baumannii to tetracycline class antibiotics. In vitro, the combination of PBT2 and zinc with either tetracycline, doxycycline, or tigecycline was shown to be bactericidal against multidrug-resistant A. baumannii, and any resistance that did arise imposed a fitness cost. PBT2 and zinc disrupted metal ion homeostasis in A. baumannii, increasing cellular zinc and copper while decreasing magnesium accumulation. Using a murine model of pulmonary infection, treatment with PBT2 in combination with tetracycline or tigecycline proved efficacious against multidrug-resistant A. baumannii. These findings suggest that PBT2 may find utility as a resistance breaker to rescue the efficacy of tetracycline-class antibiotics commonly employed to treat multidrug-resistant A. baumannii infections. IMPORTANCE Within intensive care unit settings, multidrug-resistant (MDR) Acinetobacter baumannii is a major cause of ventilator-associated pneumonia, and hospital-associated outbreaks are becoming increasingly widespread. Antibiotic treatment of A. baumannii infection is often compromised by MDR strains resistant to last-resort β-lactam (e.g., carbapenems), polymyxin, and tetracycline class antibiotics. During the on-going COVID-19 pandemic, secondary bacterial infection by A. baumannii has been associated with a 2-fold increase in COVID-19-related mortality. With a rise in antibiotic resistance and a reduction in new antibiotic discovery, it is imperative to investigate alternative therapeutic regimens that complement the use of current antibiotic treatment strategies. Rescuing the efficacy of existing therapies for the treatment of MDR A. baumannii infection represents a financially viable pathway, reducing time, cost, and risk associated with drug innovation.
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Prieto Martin Gil S, Tajuelo A, López-Siles M, McConnell MJ. Subinhibitory Concentrations of Clinically-Relevant Antimicrobials Affect Resistance-Nodulation-Division Family Promoter Activity in Acinetobacter baumannii. Front Microbiol 2021; 12:780201. [PMID: 34925284 PMCID: PMC8678518 DOI: 10.3389/fmicb.2021.780201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/11/2021] [Indexed: 11/26/2022] Open
Abstract
Efflux pumps contribute to multidrug resistance in Acinetobacter baumannii due to their ability to expel a wide variety of structurally unrelated compounds. This study aimed to characterize the effect of subinhibitory concentrations of clinically-relevant antibiotics and disinfectants on the promoter activity of members of the Resistance-Nodulation-Division (RND) family in A. baumannii. The promoter regions from three RND efflux pumps (AdeABC, AdeFGH and AdeIJK) and the AdeRS regulatory system from three different A. baumannii strains (ATCC 17961, ATCC 17978, and ATCC 19606) were cloned into a luciferase reporter system (pLPV1Z). Promoter activity was quantitatively assessed in both exponential and stationary phase cultures after exposure to subinhibitory concentrations of four antibiotics from different classes (rifampicin, meropenem, tigecycline and colistin) and two disinfectants (ethanol and chlorhexidine). Subinhibitory concentrations of the compounds tested had variable effects on promoter activity that were highly dependent on the A. baumannii strain, the compound tested and the growth phase. Fold changes in AdeABC promoter activity ranged from 1.97 to 113.7, in AdeFGH from −5.6 to 1.13, in AdeIJK from −2.5 to 2, and in AdeRS from −36.2 to −1.32. Taken together, these results indicate that subinhibitory concentrations of clinically-relevant antibiotics and disinfectants affect the promoter activity of RND family members in A. baumannii in a strain and growth phase dependent manner. These results may have important implications for the treatment of infections caused by A. baumannii.
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Affiliation(s)
- Sonia Prieto Martin Gil
- Intrahospital Infections Laboratory, National Center for Microbiology, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Ana Tajuelo
- Intrahospital Infections Laboratory, National Center for Microbiology, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Mireia López-Siles
- Intrahospital Infections Laboratory, National Center for Microbiology, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Michael J McConnell
- Intrahospital Infections Laboratory, National Center for Microbiology, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
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27
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Forde BM, De Oliveira DMP, Falconer C, Graves B, Harris PNA. Strengths and caveats of identifying resistance genes from whole genome sequencing data. Expert Rev Anti Infect Ther 2021; 20:533-547. [PMID: 34852720 DOI: 10.1080/14787210.2022.2013806] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Antimicrobial resistance (AMR) continues to present major challenges to modern healthcare. Recent advances in whole-genome sequencing (WGS) have made the rapid molecular characterization of AMR a realistic possibility for diagnostic laboratories; yet major barriers to clinical implementation exist. AREAS COVERED We describe and compare short- and long-read sequencing platforms, typical components of bioinformatics pipelines, tools for AMR gene detection and the relative merits of read- or assembly-based approaches. The challenges of characterizing mobile genetic elements from genomic data are outlined, as well as the complexities inherent to the prediction of phenotypic resistance from WGS. Practical obstacles to implementation in diagnostic laboratories, the critical role of quality control and external quality assurance, as well as standardized reporting standards are also discussed. Future directions, such as the application of machine-learning and artificial intelligence algorithms, linked to clinically meaningful outcomes, may offer a new paradigm for the clinical application of AMR prediction. EXPERT OPINION AMR prediction from WGS data presents an exciting opportunity to advance our capacity to comprehensively characterize infectious pathogens in a rapid manner, ultimately aiming to improve patient outcomes. Collaborative efforts between clinicians, scientists, regulatory bodies and healthcare administrators will be critical to achieve the full promise of this approach.
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Affiliation(s)
- Brian M Forde
- University of Queensland, Faculty of Medicine, Uq Centre for Clinical Research, Royal Brisbane and Woman's Hospital, Herston, Australia
| | - David M P De Oliveira
- University of Queensland, Faculty of Science, School of Chemistry and Molecular Biosciences, St Lucia, Australia
| | - Caitlin Falconer
- University of Queensland, Faculty of Medicine, Uq Centre for Clinical Research, Royal Brisbane and Woman's Hospital, Herston, Australia
| | - Bianca Graves
- Herston Infectious Disease Institute, Royal Brisbane & Women's Hospital, Herston, Australia
| | - Patrick N A Harris
- University of Queensland, Faculty of Medicine, Uq Centre for Clinical Research, Royal Brisbane and Woman's Hospital, Herston, Australia.,Herston Infectious Disease Institute, Royal Brisbane & Women's Hospital, Herston, Australia.,Central Microbiology, Pathology Queensland, Royal Brisbane & Women's Hospital, Herston, Australia
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Kumar S, Anwer R, Azzi A. Virulence Potential and Treatment Options of Multidrug-Resistant (MDR) Acinetobacter baumannii. Microorganisms 2021; 9:microorganisms9102104. [PMID: 34683425 PMCID: PMC8541637 DOI: 10.3390/microorganisms9102104] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/18/2021] [Accepted: 09/21/2021] [Indexed: 12/12/2022] Open
Abstract
Acinetobacter baumannii is an opportunistic pathogen which is undoubtedly known for a high rate of morbidity and mortality in hospital-acquired infections. A. baumannii causes life-threatening infections, including; ventilator-associated pneumonia (VAP), meningitis, bacteremia, and wound and urinary tract infections (UTI). In 2017, the World Health Organization listed A. baumannii as a priority-1 pathogen. The prevalence of A. baumannii infections and outbreaks emphasizes the direct need for the use of effective therapeutic agents for treating such infections. Available antimicrobials, such as; carbapenems, tigecycline, and colistins have insufficient effectiveness due to the appearance of multidrug-resistant strains, accentuating the need for alternative and novel therapeutic remedies. To understand and overcome this menace, the knowledge of recent discoveries on the virulence factors of A. baumannii is needed. Herein, we summarized the role of various virulence factors, including; outer membrane proteins, efflux pumps, biofilm, penicillin-binding proteins, and siderophores/iron acquisition systems. We reviewed the recent scientific literature on different A. baumannii virulence factors and the effective antimicrobial agents for the treatment and management of bacterial infections.
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Affiliation(s)
- Sunil Kumar
- Department of Biotechnology, Maharishi Markandeshwar (Deemed to Be University), Mullana, Ambala 133207, India;
| | - Razique Anwer
- Department of Pathology, College of Medicine, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 13317-4233, Saudi Arabia;
| | - Arezki Azzi
- Department of Biochemistry, College of Medicine, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 13317-4233, Saudi Arabia
- Correspondence:
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Salam LB, Obayori OS, Ilori MO, Amund OO. Impact of spent engine oil contamination on the antibiotic resistome of a tropical agricultural soil. ECOTOXICOLOGY (LONDON, ENGLAND) 2021; 30:1251-1271. [PMID: 33993436 DOI: 10.1007/s10646-021-02422-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/28/2021] [Indexed: 06/12/2023]
Abstract
Profiling of hydrocarbon-contaminated soils for antibiotic resistance genes (ARGs) is becoming increasingly important due to emerging realities of their preponderance in hydrocarbon-inundated matrices. In this study, the antibiotic resistome of an agricultural soil (1S) and agricultural soil contaminated with spent engine oil (AB1) were evaluated via functional annotation of the open reading frames (ORFs) of their metagenomes using the comprehensive antibiotic database (CARD) and KEGG KofamKOALA. CARD analysis of AB1 metagenome revealed the detection of 24 AMR (antimicrobial resistance) gene families, 66 ARGs, and the preponderance (69.7%) of ARGs responsible for antibiotic efflux in AB1 metagenome. CARD analysis of 1S metagenome revealed four AMR gene families and five ARGs. Functional annotation of the two metagenomes using KofamKOALA showed 171 ARGs in AB1 and 29 ARGs in 1S, respectively. Majority of the detected ARGs in AB1 (121; 70.8%) and 1S (16; 55.2%) using KofamKOALA are responsible for antibiotic efflux while ARGs for other resistance mechanisms were also detected. All the five major antibiotic efflux pump systems were detected in AB1 metagenome, though majority of the ARGs for antibiotic efflux belong to the RND (resistance-nodulation-cell division) and MFS (major facilitator superfamily) efflux systems. Significant differences observed in the ARGs recovered from 1S and AB1 metagenomes were statistically validated (P < 0.05). SEO contamination is believed to be responsible for ARGs increase in AB1 metagenome via mechanisms of cross-resistance especially with efflux pumps. The detection of these ARGs is of great public health concern in this era of multidrug resistant isolates resurgence.
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Affiliation(s)
- Lateef Babatunde Salam
- Department of Biological Sciences, Microbiology Unit, Summit University, Offa, Kwara, Nigeria.
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30
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Sumyk M, Himpich S, Foong WE, Herrmann A, Pos KM, Tam HK. Binding of Tetracyclines to Acinetobacter baumannii TetR Involves Two Arginines as Specificity Determinants. Front Microbiol 2021; 12:711158. [PMID: 34349752 PMCID: PMC8326586 DOI: 10.3389/fmicb.2021.711158] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 06/23/2021] [Indexed: 11/13/2022] Open
Abstract
Acinetobacter baumannii is an important nosocomial pathogen that requires thoughtful consideration in the antibiotic prescription strategy due to its multidrug resistant phenotype. Tetracycline antibiotics have recently been re-administered as part of the combination antimicrobial regimens to treat infections caused by A. baumannii. We show that the TetA(G) efflux pump of A. baumannii AYE confers resistance to a variety of tetracyclines including the clinically important antibiotics doxycycline and minocycline, but not to tigecycline. Expression of tetA(G) gene is regulated by the TetR repressor of A. baumannii AYE (AbTetR). Thermal shift binding experiments revealed that AbTetR preferentially binds tetracyclines which carry a O-5H moiety in ring B, whereas tetracyclines with a 7-dimethylamino moiety in ring D are less well-recognized by AbTetR. Confoundingly, tigecycline binds to AbTetR even though it is not transported by TetA(G) efflux pump. Structural analysis of the minocycline-bound AbTetR-Gln116Ala variant suggested that the non-conserved Arg135 interacts with the ring D of minocycline by cation-π interaction, while the invariant Arg104 engages in H-bonding with the O-11H of minocycline. Interestingly, the Arg135Ala variant exhibited a binding preference for tetracyclines with an unmodified ring D. In contrast, the Arg104Ala variant preferred to bind tetracyclines which carry a O-6H moiety in ring C except for tigecycline. We propose that Arg104 and Arg135, which are embedded at the entrance of the AbTetR binding pocket, play important roles in the recognition of tetracyclines, and act as a barrier to prevent the release of tetracycline from its binding pocket upon AbTetR activation. The binding data and crystal structures obtained in this study might provide further insight for the development of new tetracycline antibiotics to evade the specific efflux resistance mechanism deployed by A. baumannii.
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Affiliation(s)
- Manuela Sumyk
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Stephanie Himpich
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Wuen Ee Foong
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Andrea Herrmann
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Klaas M Pos
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Heng-Keat Tam
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
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31
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Lucaßen K, Müller C, Wille J, Xanthopoulou K, Hackel M, Seifert H, Higgins PG. Prevalence of RND efflux pump regulator variants associated with tigecycline resistance in carbapenem-resistant Acinetobacter baumannii from a worldwide survey. J Antimicrob Chemother 2021; 76:1724-1730. [PMID: 33760099 DOI: 10.1093/jac/dkab079] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 02/18/2021] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To determine the most common tigecycline resistance mechanisms in carbapenem-resistant Acinetobacter baumannii isolates obtained during the global Tigecycline Evaluation Surveillance Trial (TEST). METHODS Tigecycline MICs were determined by broth microdilution. WGS was used to screen for the previously identified tigecycline resistance mechanisms, as well as mutations in resistance-nodulation-cell division (RND)-type efflux pump regulators. RESULTS From a total 313 isolates, 113 genetically unique tigecycline-resistant isolates were analysed. The most frequent and worldwide distributed mechanism associated with tigecycline resistance was disruption of adeN, which encodes the repressor of the RND efflux pump AdeIJK, either by IS elements or nucleotide deletions causing premature stop codons. However, mutations leading to amino acid substitutions and disruption by IS elements within the two-component regulatory system adeRS, which regulates expression of the AdeABC efflux pump, correlate with higher tigecycline MICs, but these were found less frequently and were mainly restricted to Southern European countries. Furthermore, an altered version of tviB was identified in several tigecycline-resistant isolates that did not have putative resistance mutations within RND-type regulators. The resistance determinants tet(A) and tet(X), as well as resistance mutations in putative resistance determinants trm, plsC, rrf, msbA and genes encoding 30S ribosomal proteins, were not identified in any isolate. CONCLUSIONS The most prevalent tigecycline resistance mechanisms were caused by alterations in the regulators of RND-type efflux pumps. These data provide the basis for further characterization of regulator alterations and their contribution to increased efflux and tigecycline resistance, and also should be taken into account in drug discovery programmes to overcome the contribution of efflux pumps.
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Affiliation(s)
- Kai Lucaßen
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany
| | - Carina Müller
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Julia Wille
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Kyriaki Xanthopoulou
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Meredith Hackel
- International Health Management Associates, 2122 Palmer Drive, Schaumburg, IL 60173, USA
| | - Harald Seifert
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Paul G Higgins
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
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Shared and Unique Evolutionary Trajectories to Ciprofloxacin Resistance in Gram-Negative Bacterial Pathogens. mBio 2021; 12:e0098721. [PMID: 34154405 PMCID: PMC8262867 DOI: 10.1128/mbio.00987-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Resistance to the broad-spectrum antibiotic ciprofloxacin is detected at high rates for a wide range of bacterial pathogens. To investigate the dynamics of ciprofloxacin resistance development, we applied a comparative resistomics workflow for three clinically relevant species of Gram-negative bacteria: Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa. We combined experimental evolution in a morbidostat with deep sequencing of evolving bacterial populations in time series to reveal both shared and unique aspects of evolutionary trajectories. Representative clone characterization by sequencing and MIC measurements enabled direct assessment of the impact of mutations on the extent of acquired drug resistance. In all three species, we observed a two-stage evolution: (i) early ciprofloxacin resistance reaching 4- to 16-fold the MIC for the wild type, commonly as a result of single mutations in DNA gyrase target genes (gyrA or gyrB), and (ii) additional genetic alterations affecting the transcriptional control of the drug efflux machinery or secondary target genes (DNA topoisomerase parC or parE).
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Abstract
Acinetobacter spp. have become of increased clinical importance as studies have shown the antimicrobial resistant potential of these species. Efflux pumps can lead to reduced susceptibility to a variety of antibiotics and are present in large number across Acinetobacter spp. There are six families of efflux pumps that have been shown to be of clinical relevance: the major facilitator superfamily (MFS), small multidrug resistance (SMR) family, ATP-binding cassette (ABC) family, multidrug and toxic compound extrusion (MATE) family, proteobacterial antimicrobial compound efflux (PACE) family, and the resistance-nodulation-division (RND) family. Much work has been done for understanding and characterizing the roles these efflux pumps play in relation to antimicrobial resistance and the physiology of these bacteria. RND efflux pumps, with their expansive substrate profiles, are a major component of Acinetobacter spp. antimicrobial resistance. New discoveries over the last decade have shed light on the complex regulation of these efflux pumps, leading to greater understanding and the potential of slowing the reduced susceptibility seen in these bacterial species.
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Cryo-EM Determination of Eravacycline-Bound Structures of the Ribosome and the Multidrug Efflux Pump AdeJ of Acinetobacter baumannii. mBio 2021; 12:e0103121. [PMID: 34044590 PMCID: PMC8263017 DOI: 10.1128/mbio.01031-21] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antibiotic-resistant strains of the Gram-negative pathogen Acinetobacter baumannii have emerged as a significant global health threat. One successful therapeutic option to treat bacterial infections has been to target the bacterial ribosome. However, in many cases, multidrug efflux pumps within the bacterium recognize and extrude these clinically important antibiotics designed to inhibit the protein synthesis function of the bacterial ribosome. Thus, multidrug efflux within A. baumannii and other highly drug-resistant strains is a major cause of failure of drug-based treatments of infectious diseases. We here report the first structures of the Acinetobacterdrug efflux (Ade)J pump in the presence of the antibiotic eravacycline, using single-particle cryo-electron microscopy (cryo-EM). We also describe cryo-EM structures of the eravacycline-bound forms of the A. baumannii ribosome, including the 70S, 50S, and 30S forms. Our data indicate that the AdeJ pump primarily uses hydrophobic interactions to bind eravacycline, while the 70S ribosome utilizes electrostatic interactions to bind this drug. Our work here highlights how an antibiotic can bind multiple bacterial targets through different mechanisms and potentially enables drug optimization by taking advantage of these different modes of ligand binding.
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Identification of a Novel Ciprofloxacin Tolerance Gene, aciT, Which Contributes to Filamentation in Acinetobacter baumannii. Antimicrob Agents Chemother 2021; 65:AAC.01400-20. [PMID: 33820764 PMCID: PMC8316044 DOI: 10.1128/aac.01400-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 03/20/2021] [Indexed: 01/19/2023] Open
Abstract
Fluoroquinolones are one of the most prescribed broad-spectrum antibiotics. However, their effectiveness is being compromised by high rates of resistance in clinically important organisms, including Acinetobacter baumannii. We sought to investigate the transcriptomic and proteomic responses of the clinical A. baumannii strain AB5075-UW upon exposure to subinhibitory concentrations of ciprofloxacin. Our transcriptomics and proteomics analyses found that the most highly expressed genes and proteins were components of the intact prophage phiOXA. The next most highly expressed gene (and its protein product) under ciprofloxacin stress was a hypothetical gene, ABUW_0098, named here the Acinetobacterciprofloxacin tolerance (aciT) gene. Disruption of this gene resulted in higher susceptibility to ciprofloxacin, and complementation of the mutant with a cloned aciT gene restored ciprofloxacin tolerance to parental strain levels. Microscopy studies revealed that aciT is essential for filamentation during ciprofloxacin stress in A. baumannii. Sequence analysis of aciT indicates the encoded protein is likely to be localized to the cell membrane. Orthologs of aciT are found widely in the genomes of species from the Moraxellaceae family and are well conserved in Acinetobacter species, suggesting an important role. With these findings taken together, this study has identified a new gene conferring tolerance to ciprofloxacin, likely by enabling filamentation in response to the antibiotic.
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Vahhabi A, Hasani A, Rezaee MA, Baradaran B, Hasani A, Samadi Kafil H, Abbaszadeh F, Dehghani L. A plethora of carbapenem resistance in Acinetobacter baumannii: no end to a long insidious genetic journey. J Chemother 2021; 33:137-155. [PMID: 33243098 DOI: 10.1080/1120009x.2020.1847421] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 10/23/2020] [Accepted: 11/02/2020] [Indexed: 01/21/2023]
Abstract
Acinetobacter baumannii, notorious for causing nosocomial infections especially in patients admitted to intensive care unit (ICU) and burn units, is best at displaying resistance to all existing antibiotic classes. Consequences of high potential for antibiotic resistance has resulted in extensive drug or even pan drug resistant A. baumannii. Carbapenems, mainly imipenem and meropenem, the last resort for the treatment of A. baumannii infections have fallen short due to the emergence of carbapenem resistant A. baumannii (CRAB). Though enzymatic degradation by production of class D β-lactamases (Oxacillinases) and class B β-lactamases (Metallo β-lactamases) is the core mechanism of carbapenem resistance in A. baumannii; however over-expression of efflux pumps such as resistance-nodulation cell division (RND) family and variant form of porin proteins such as CarO have been implicated for CRAB inception. Transduction and outer membrane vesicles-mediated transfer play a role in carbapenemase determinants spread. Colistin, considered as the most promising antibacterial agent, nevertheless faces adverse effects flaws. Cefiderocol, eravacycline, new β-lactam antibiotics, non-β-lactam-β-lactamase inhibitors, polymyxin B-derived molecules and bacteriophages are some other new treatment options streamlined.
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Affiliation(s)
- Abolfazl Vahhabi
- Immunology Research Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
- Department of Bacteriology and Virology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
| | - Alka Hasani
- Immunology Research Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
- Department of Bacteriology and Virology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
- Clinical Research Development Unit, Sina Educational, Research and Treatment Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
| | - Mohammad Ahangarzadeh Rezaee
- Immunology Research Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
- Department of Bacteriology and Virology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
| | - Behzad Baradaran
- Immunology Research Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
| | - Akbar Hasani
- Department of Clinical Biochemistry and Laboratory Sciences, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I. R. Iran
| | - Hossein Samadi Kafil
- Department of Bacteriology and Virology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
| | - Faeze Abbaszadeh
- Department of Bacteriology and Virology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
| | - Leila Dehghani
- Clinical Research Development Unit, Sina Educational, Research and Treatment Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, I.R. Iran
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Salehi B, Ghalavand Z, Yadegar A, Eslami G. Characteristics and diversity of mutations in regulatory genes of resistance-nodulation-cell division efflux pumps in association with drug-resistant clinical isolates of Acinetobacter baumannii. Antimicrob Resist Infect Control 2021; 10:53. [PMID: 33691788 PMCID: PMC7944621 DOI: 10.1186/s13756-021-00924-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 03/02/2021] [Indexed: 02/06/2023] Open
Abstract
Background This study was aimed to characterize the genetic diversity and expression of three putative resistance-nodulation-cell division (RND)-type efflux systems and their contribution to multidrug efflux in clinical isolates of Acinetobacter baumannii. Methods Antimicrobial susceptibility testing of 95 A. baumannii isolates was determined by Kirby-Bauer disk diffusion for 18 antibiotics and minimum inhibitory concentration (MIC) of colistin was determined by the broth microdilution method. Moreover, the MIC of five classes of antibiotics was assessed using E-test strips in the presence and absence of phenylalanine-arginine beta-naphthylamide (PAβN). Regulatory genes of the RND efflux pumps (adeRS, adeL, adeN and baeSR) were subjected to sequencing. The relative expression of adeB, adeG and adeJ genes was determined by quantitative real-time PCR (qRT-PCR). Results Overall, the majority of isolates (94%) were extensively drug-resistant (XDR). In the phenotypic assay, efflux pump activity was observed in 40% of the isolates against multiple antibiotics mainly tigecycline. However, we found no efflux activity against imipenem. Several amino acid substitutions were detected in the products of regulatory genes; except in AdeN. Of note, G186V mutation in AdeS was found to be associated with overexpression of its efflux pump. No insertion sequences were detected. Conclusions Our findings outlined the role of RND efflux pumps in resistance of A. baumannii to multiple antibiotics particularly tigecycline, and pointed out the importance of a variety of single mutations in the corresponding regulatory systems. Further studies are required to decipher the precise role of RND efflux pumps in multidrug-resistant clinical isolates of A. baumannii.
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Affiliation(s)
- Bahare Salehi
- Infectious Diseases and Tropical Medicine Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Zohreh Ghalavand
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Abbas Yadegar
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Gita Eslami
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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An Analysis of the Novel Fluorocycline TP-6076 Bound to Both the Ribosome and Multidrug Efflux Pump AdeJ from Acinetobacter baumannii. mBio 2021; 13:e0373221. [PMID: 35100868 PMCID: PMC8805024 DOI: 10.1128/mbio.03732-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Antibiotic resistance among bacterial pathogens continues to pose a serious global health threat. Multidrug-resistant (MDR) strains of the Gram-negative organism Acinetobacter baumannii utilize a number of resistance determinants to evade current antibiotics. One of the major resistance mechanisms employed by these pathogens is the use of multidrug efflux pumps. These pumps extrude xenobiotics directly out of bacterial cells, resulting in treatment failures when common antibiotics are administered. Here, the structure of the novel tetracycline antibiotic TP-6076, bound to both the Acinetobacter drug efflux pump AdeJ and the ribosome from Acinetobacter baumannii, using single-particle cryo-electron microscopy (cryo-EM), is elucidated. In this work, the structure of the AdeJ-TP-6076 complex is solved, and we show that AdeJ utilizes a network of hydrophobic interactions to recognize this fluorocycline. Concomitant with this, we elucidate three structures of TP-6076 bound to the A. baumannii ribosome and determine that its binding is stabilized largely by electrostatic interactions. We then compare the differences in binding modes between TP-6076 and the related tetracycline antibiotic eravacycline in both targets. These differences suggest that modifications to the tetracycline core may be able to alter AdeJ binding while maintaining interactions with the ribosome. Together, this work highlights how different mechanisms are used to stabilize the binding of tetracycline-based compounds to unique bacterial targets and provides guidance for the future clinical development of tetracycline antibiotics. IMPORTANCE Treatment of antibiotic-resistant organisms such as A. baumannii represents an ongoing issue for modern medicine. The multidrug efflux pump AdeJ serves as a major resistance determinant in A. baumannii through its action of extruding antibiotics from the cell. In this work, we use cryo-EM to show how AdeJ recognizes the experimental tetracycline antibiotic TP-6076 and prevents this drug from interacting with the A. baumannii ribosome. Since AdeJ and the ribosome use different binding modes to stabilize interactions with TP-6076, exploiting these differences may guide future drug development for combating antibiotic-resistant A. baumannii and potentially other strains of MDR bacteria.
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Verma P, Tiwari M, Tiwari V. Efflux pumps in multidrug-resistant Acinetobacter baumannii: Current status and challenges in the discovery of efflux pumps inhibitors. Microb Pathog 2021; 152:104766. [PMID: 33545327 DOI: 10.1016/j.micpath.2021.104766] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 01/13/2021] [Accepted: 01/22/2021] [Indexed: 12/14/2022]
Abstract
Acinetobacter baumannii is an ESKAPE pathogen known to cause fatal nosocomial infections. With the surge of multidrug resistance (MDR) in the bacterial system, effective treatment measures have become very limited. The MDR in A. baumannii is contributed by various factors out of which efflux pumps have gained major attention due to their broad substrate specificity and wide distribution among bacterial species. The efflux pumps are involved in the MDR as well as contribute to other physiological processes in bacteria, therefore, it is critically important to inhibit efflux pumps in order to combat emerging resistance. The present review provides insight about the different efflux pump systems in A. baumannii and their role in multidrug resistance. A major focus has been put on the different strategies and alternate therapeutics to inhibit the efflux system. This includes use of different efflux pump inhibitors-natural, synthetic or combinatorial therapy. The use of phage therapy and nanoparticles for inhibiting efflux pumps have also been discussed here. Moreover, the present review provides the knowledge of barriers in development of efflux pump inhibitors (EPIs) and their approval for commercialization. Here, different prospectives have been discussed to improve the therapeutic development process and make it more compatible for clinical use.
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Affiliation(s)
- Privita Verma
- Department of Biochemistry, Central University of Rajasthan, Bandarsindri, Ajmer, 305817, India
| | - Monalisa Tiwari
- Department of Biochemistry, Central University of Rajasthan, Bandarsindri, Ajmer, 305817, India
| | - Vishvanath Tiwari
- Department of Biochemistry, Central University of Rajasthan, Bandarsindri, Ajmer, 305817, India.
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Alattraqchi AG, Mohd Rani F, A Rahman NI, Ismail S, Cleary DW, Clarke SC, Yeo CC. Complete Genome Sequencing of Acinetobacter baumannii AC1633 and Acinetobacter nosocomialis AC1530 Unveils a Large Multidrug-Resistant Plasmid Encoding the NDM-1 and OXA-58 Carbapenemases. mSphere 2021; 6:e01076-20. [PMID: 33504662 PMCID: PMC7885321 DOI: 10.1128/msphere.01076-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/08/2021] [Indexed: 11/20/2022] Open
Abstract
Carbapenem-resistant Acinetobacter spp. are considered priority drug-resistant human-pathogenic bacteria. The genomes of two carbapenem-resistant Acinetobacter spp. clinical isolates obtained from the same tertiary hospital in Terengganu, Malaysia, namely, A. baumannii AC1633 and A. nosocomialis AC1530, were sequenced. Both isolates were found to harbor the carbapenemase genes blaNDM-1 and blaOXA-58 in a large (ca. 170 kb) plasmid designated pAC1633-1 and pAC1530, respectively, that also encodes genes that confer resistance to aminoglycosides, sulfonamides, and macrolides. The two plasmids were almost identical except for the insertion of ISAba11 and an IS4 family element in pAC1633-1, and ISAba11 along with relBE toxin-antitoxin genes flanked by inversely orientated pdif (XerC/XerD) recombination sites in pAC1530. The blaNDM-1 gene was encoded in a Tn125 composite transposon structure flanked by ISAba125, whereas blaOXA-58 was flanked by ISAba11 and ISAba3 downstream and a partial ISAba3 element upstream within a pdif module. The presence of conjugative genes in plasmids pAC1633-1/pAC1530 and their discovery in two distinct species of Acinetobacter from the same hospital are suggestive of conjugative transfer, but mating experiments failed to demonstrate transmissibility under standard laboratory conditions. Comparative sequence analysis strongly inferred that pAC1633-1/pAC1530 was derived from two separate plasmids in an IS1006-mediated recombination or transposition event. A. baumannii AC1633 also harbored three other plasmids designated pAC1633-2, pAC1633-3, and pAC1633-4. Both pAC1633-3 and pAC1633-4 are cryptic plasmids, whereas pAC1633-2 is a 12,651-bp plasmid of the GR8/GR23 Rep3-superfamily group that encodes the tetA(39) tetracycline resistance determinant in a pdif module.IMPORTANCE Bacteria of the genus Acinetobacter are important hospital-acquired pathogens, with carbapenem-resistant A. baumannii listed by the World Health Organization as the one of the top priority pathogens. Whole-genome sequencing of carbapenem-resistant A. baumannii AC1633 and A. nosocomialis AC1530, which were isolated from the main tertiary hospital in Terengganu, Malaysia, led to the discovery of a large, ca. 170-kb plasmid that harbored genes encoding the New Delhi metallo-β-lactamase-1 (NDM-1) and OXA-58 carbapenemases alongside genes that conferred resistance to aminoglycosides, macrolides, and sulfonamides. The plasmid was a patchwork of multiple mobile genetic elements and comparative sequence analysis indicated that it may have been derived from two separate plasmids through an IS1006-mediated recombination or transposition event. The presence of such a potentially transmissible plasmid encoding resistance to multiple antimicrobials warrants vigilance, as its spread to susceptible strains would lead to increasing incidences of antimicrobial resistance.
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Affiliation(s)
- Ahmed Ghazi Alattraqchi
- Faculty of Medicine, Universiti Sultan Zainal Abidin, Kuala Terengganu, Terengganu, Malaysia
| | - Farahiyah Mohd Rani
- Faculty of Medicine, Universiti Sultan Zainal Abidin, Kuala Terengganu, Terengganu, Malaysia
| | - Nor Iza A Rahman
- Faculty of Medicine, Universiti Sultan Zainal Abidin, Kuala Terengganu, Terengganu, Malaysia
| | - Salwani Ismail
- Faculty of Medicine, Universiti Sultan Zainal Abidin, Kuala Terengganu, Terengganu, Malaysia
| | - David W Cleary
- Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
- NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Trust, Southampton, United Kingdom
| | - Stuart C Clarke
- Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
- NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Trust, Southampton, United Kingdom
- Global Health Research Institute, University of Southampton, Southampton, United Kingdom
- School of Postgraduate Studies, International Medical University, Kuala Lumpur, Malaysia
- Centre for Translational Research, IMU Institute for Research, Development and Innovation (IRDI), Kuala Lumpur, Malaysia
| | - Chew Chieng Yeo
- Faculty of Medicine, Universiti Sultan Zainal Abidin, Kuala Terengganu, Terengganu, Malaysia
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McCarthy RR, Larrouy-Maumus GJ, Meiqi Tan MGC, Wareham DW. Antibiotic Resistance Mechanisms and Their Transmission in Acinetobacter baumannii. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1313:135-153. [PMID: 34661894 DOI: 10.1007/978-3-030-67452-6_7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The discovery of penicillin over 90 years ago and its subsequent uptake by healthcare systems around the world revolutionised global health. It marked the beginning of a golden age in antibiotic discovery with new antibiotics readily discovered from natural sources and refined into therapies that saved millions of lives. Towards the end of the last century, the rate of discovery slowed to a near standstill. The lack of discovery is compounded by the rapid emergence and spread of bacterial pathogens that exhibit resistance to multiple antibiotic therapies and threaten the sustainability of global healthcare systems. Acinetobacter baumannii is an opportunistic pathogen whose prevalence and impact has grown significantly over the last 20 years. It is recognised as a barometer of the antibiotic resistance crisis due to the diverse array of mechanisms by which it can become resistant.
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Affiliation(s)
- Ronan R McCarthy
- Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UK.
| | - Gerald J Larrouy-Maumus
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London, UK
| | - Mei Gei C Meiqi Tan
- Antimicrobial Research Group, Blizard Institute, Queen Mary University London, London, UK
| | - David W Wareham
- Antimicrobial Research Group, Blizard Institute, Queen Mary University London, London, UK
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Systematic Investigation of Resistance Evolution to Common Antibiotics Reveals Conserved Collateral Responses across Common Human Pathogens. Antimicrob Agents Chemother 2020; 65:AAC.01273-20. [PMID: 33106260 PMCID: PMC7927859 DOI: 10.1128/aac.01273-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/06/2020] [Indexed: 12/22/2022] Open
Abstract
As drug resistance continues to grow, treatment strategies that turn resistance into a disadvantage for the organism will be increasingly relied upon to treat infections and to lower the rate of multidrug resistance. The majority of work in this area has investigated how resistance evolution toward a single antibiotic effects a specific organism’s collateral response to a wide variety of antibiotics. The results of these studies have been used to identify networks of drugs which can be used to drive resistance in a particular direction. As drug resistance continues to grow, treatment strategies that turn resistance into a disadvantage for the organism will be increasingly relied upon to treat infections and to lower the rate of multidrug resistance. The majority of work in this area has investigated how resistance evolution toward a single antibiotic effects a specific organism’s collateral response to a wide variety of antibiotics. The results of these studies have been used to identify networks of drugs which can be used to drive resistance in a particular direction. However, little is known about the extent of evolutionary conservation of these responses across species. We sought to address this knowledge gap by performing a systematic resistance evolution study of the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae) under uniform growth conditions using five clinically relevant antibiotics with diverse modes of action. Evolved lineages were analyzed for collateral effects and the molecular mechanisms behind the observed phenotypes. Fourteen universal cross-resistance and two global collateral sensitivity relationships were found among the lineages. Genomic analyses revealed drug-dependent divergent and conserved evolutionary trajectories among the pathogens. Our findings suggest that collateral responses may be preserved across species. These findings may help extend the contribution of previous collateral network studies in the development of treatment strategies to address the problem of antibiotic resistance.
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Leus IV, Adamiak J, Trinh AN, Smith RD, Smith L, Richardson S, Ernst RK, Zgurskaya HI. Inactivation of AdeABC and AdeIJK efflux pumps elicits specific nonoverlapping transcriptional and phenotypic responses in Acinetobacter baumannii. Mol Microbiol 2020; 114:1049-1065. [PMID: 32858760 DOI: 10.1111/mmi.14594] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/17/2020] [Indexed: 12/24/2022]
Abstract
Multidrug resistant (MDR) strains of Acinetobacter baumannii present a serious clinical challenge. The development of antibiotic resistance in this species is enabled by efflux pumps of the Resistance-Nodulation-Division (RND) superfamily of proteins creating an efficient permeability barrier for antibiotics. At least three RND pumps, AdeABC, AdeIJK, and AdeFGH are encoded in the A. baumannii genome and are reported to contribute to antibiotic resistance in clinical isolates. In this study, we analyzed the contributions of AdeABC and AdeIJK in antibiotic resistance and growth physiology of the two MDR strains, AYE and AB5075. We found that not only the two pumps have nonoverlapping substrate specificities, their inactivation leads to specific nonoverlapping changes in gene expression as determined by RNA sequencing and confirmed by gene knockouts and growth phenotypes. Our results suggest that inactivation of AdeIJK elicits broader changes in the abundances of mRNAs and this response is modified in the absence of AdeB. In contrast, inactivation of AdeB leads to a focused cellular response, which is not sensitive to the activity of AdeIJK. We identified additional efflux pumps and transcriptional regulators that contribute to MDR phenotype of clinical A. baumannii isolates.
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Affiliation(s)
- Inga V Leus
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA
| | - Justyna Adamiak
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA
| | - Anhthu N Trinh
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA
| | - Richard D Smith
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, MD, USA
| | - Lauren Smith
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA
| | - Sophie Richardson
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, MD, USA
| | - Helen I Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK, USA
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Proteomic and Systematic Functional Profiling Unveils Citral Targeting Antibiotic Resistance, Antioxidant Defense, and Biofilm-Associated Two-Component Systems of Acinetobacter baumannii To Encumber Biofilm and Virulence Traits. mSystems 2020; 5:5/6/e00986-20. [PMID: 33203690 PMCID: PMC7677002 DOI: 10.1128/msystems.00986-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acinetobacter baumannii is a nosocomial-infection-causing bacterium and also possesses multidrug resistance to a wide range of conventional antibiotics. The biofilm-forming ability of A. baumannii plays a major role in its resistance and persistence. There is an alarming need for novel treatment strategies to control A. baumannii biofilm-associated issues. The present study demonstrated the strong antibiofilm and antivirulence efficacy of citral against A. baumannii. In addition, proteomic analysis revealed the multitarget potential of citral against A. baumannii. Furthermore, citral treatment enhances the susceptibility of A. baumannii to the host innate immune system and reactive oxygen species (ROS). Cytotoxicity analysis revealed the nonfatal effect of citral on human PBMCs. Therefore, citral could be the safest therapeutic compound and can be taken for further clinical evaluation for the treatment of biofilm-associated infections by A. baumannii. Acinetobacter baumannii has been reported as a multidrug-resistant bacterium due to biofilms and antimicrobial resistance mechanisms. Hence, novel therapeutic strategies are necessary to overcome A. baumannii infections. This study revealed that citral at 200 μg/ml attenuated A. baumannii biofilms by up to 90% without affecting viability. Furthermore, microscopic analyses and in vitro assays confirmed the antibiofilm efficacy of citral. The global effect of citral on A. baumannii was evaluated by proteomic, transcriptional, and in silico approaches. Two-dimensional (2D) gel electrophoresis and matrix-assisted laser desorption ionization–time of flight/time of flight (MALDI-TOF/TOF) analyses were used to assess the effect of citral on the A. baumannii cellular proteome. Quantitative real-time PCR (qPCR) analysis was done to validate the proteomic data and identify the differentially expressed A. baumannii genes. Protein-protein interactions, gene enrichment, and comparative gene network analyses were performed to explore the interactions and functional attributes of differentially expressed proteins of A. baumannii. Global omics-based analyses revealed that citral targeted various mechanisms such as biofilm formation, antibiotic resistance, antioxidant defense, iron acquisition, and type II and type IV secretion systems. The results of antioxidant analyses and antibiotic sensitivity, blood survival, lipase, and hemolysis assays validated the proteomic results. Cytotoxicity analysis showed a nontoxic effect of citral on peripheral blood mononuclear cells (PBMCs). Overall, the current study unveiled that citral has multitarget efficacy to inhibit the biofilm formation and virulence of A. baumannii. IMPORTANCEAcinetobacter baumannii is a nosocomial-infection-causing bacterium and also possesses multidrug resistance to a wide range of conventional antibiotics. The biofilm-forming ability of A. baumannii plays a major role in its resistance and persistence. There is an alarming need for novel treatment strategies to control A. baumannii biofilm-associated issues. The present study demonstrated the strong antibiofilm and antivirulence efficacy of citral against A. baumannii. In addition, proteomic analysis revealed the multitarget potential of citral against A. baumannii. Furthermore, citral treatment enhances the susceptibility of A. baumannii to the host innate immune system and reactive oxygen species (ROS). Cytotoxicity analysis revealed the nonfatal effect of citral on human PBMCs. Therefore, citral could be the safest therapeutic compound and can be taken for further clinical evaluation for the treatment of biofilm-associated infections by A. baumannii.
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45
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Geisinger E, Mortman NJ, Dai Y, Cokol M, Syal S, Farinha A, Fisher DG, Tang AY, Lazinski DW, Wood S, Anthony J, van Opijnen T, Isberg RR. Antibiotic susceptibility signatures identify potential antimicrobial targets in the Acinetobacter baumannii cell envelope. Nat Commun 2020; 11:4522. [PMID: 32908144 PMCID: PMC7481262 DOI: 10.1038/s41467-020-18301-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 08/13/2020] [Indexed: 11/13/2022] Open
Abstract
A unique, protective cell envelope contributes to the broad drug resistance of the nosocomial pathogen Acinetobacter baumannii. Here we use transposon insertion sequencing to identify A. baumannii mutants displaying altered susceptibility to a panel of diverse antibiotics. By examining mutants with antibiotic susceptibility profiles that parallel mutations in characterized genes, we infer the function of multiple uncharacterized envelope proteins, some of which have roles in cell division or cell elongation. Remarkably, mutations affecting a predicted cell wall hydrolase lead to alterations in lipooligosaccharide synthesis. In addition, the analysis of altered susceptibility signatures and antibiotic-induced morphology patterns allows us to predict drug synergies; for example, certain beta-lactams appear to work cooperatively due to their preferential targeting of specific cell wall assembly machineries. Our results indicate that the pathogen may be effectively inhibited by the combined targeting of multiple pathways critical for envelope growth.
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Affiliation(s)
- Edward Geisinger
- Department of Biology, Northeastern University, Boston, MA, 02115, USA.
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
| | - Nadav J Mortman
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Yunfei Dai
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Murat Cokol
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Sapna Syal
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Andrew Farinha
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Delaney G Fisher
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Amy Y Tang
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - David W Lazinski
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Stephen Wood
- Biology Department, Boston College, Chestnut Hill, MA, 02467, USA
| | - Jon Anthony
- Biology Department, Boston College, Chestnut Hill, MA, 02467, USA
| | - Tim van Opijnen
- Biology Department, Boston College, Chestnut Hill, MA, 02467, USA
| | - Ralph R Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
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47
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Antibiotic Resistance Profiles, Molecular Mechanisms and Innovative Treatment Strategies of Acinetobacter baumannii. Microorganisms 2020; 8:microorganisms8060935. [PMID: 32575913 PMCID: PMC7355832 DOI: 10.3390/microorganisms8060935] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/19/2020] [Accepted: 06/19/2020] [Indexed: 12/18/2022] Open
Abstract
Antibiotic resistance is one of the biggest challenges for the clinical sector and industry, environment and societal development. One of the most important pathogens responsible for severe nosocomial infections is Acinetobacter baumannii, a Gram-negative bacterium from the Moraxellaceae family, due to its various resistance mechanisms, such as the β-lactamases production, efflux pumps, decreased membrane permeability and altered target site of the antibiotic. The enormous adaptive capacity of A. baumannii and the acquisition and transfer of antibiotic resistance determinants contribute to the ineffectiveness of most current therapeutic strategies, including last-line or combined antibiotic therapy. In this review, we will present an update of the antibiotic resistance profiles and underlying mechanisms in A. baumannii and the current progress in developing innovative strategies for combating multidrug-resistant A. baumannii (MDRAB) infections.
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48
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Allen JL, Tomlinson BR, Casella LG, Shaw LN. Regulatory networks important for survival of Acinetobacter baumannii within the host. Curr Opin Microbiol 2020; 55:74-80. [PMID: 32388085 DOI: 10.1016/j.mib.2020.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/28/2020] [Accepted: 03/02/2020] [Indexed: 12/25/2022]
Abstract
Acinetobacter baumannii is known for its intrinsic resistance to conventional antibiotic treatment and hypervirulence during infection. This coupled with its extraordinary capacity to survive in myriad harsh environments has led to increasing rates of infection in clinical settings. Numerous studies have characterized the virulence factors and resistance genes in A. baumannii responsible for the detrimental outcomes seen in patients; however, the role of regulatory factors in controlling the expression of these genes remains less well explored. Herein we discuss the latest and most influential findings on the regulatory network of A. baumannii, focusing on the transcription factors, two-component systems, and sRNAs. We place particular focus on those identified as being crucial for sensing and responding to continually changing environments, and influencing survival and virulence when engaging with the human host.
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Affiliation(s)
- Jessie L Allen
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, 4202 East Fowler Avenue, ISA 2015, Tampa, FL 33620-5150, USA
| | - Brooke R Tomlinson
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, 4202 East Fowler Avenue, ISA 2015, Tampa, FL 33620-5150, USA
| | - Leila G Casella
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, 4202 East Fowler Avenue, ISA 2015, Tampa, FL 33620-5150, USA
| | - Lindsey N Shaw
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, 4202 East Fowler Avenue, ISA 2015, Tampa, FL 33620-5150, USA.
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49
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Álvarez VE, Quiroga MP, Galán AV, Vilacoba E, Quiroga C, Ramírez MS, Centrón D. Crucial Role of the Accessory Genome in the Evolutionary Trajectory of Acinetobacter baumannii Global Clone 1. Front Microbiol 2020; 11:342. [PMID: 32256462 PMCID: PMC7093585 DOI: 10.3389/fmicb.2020.00342] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 02/17/2020] [Indexed: 01/08/2023] Open
Abstract
Acinetobacter baumannii is one of the most important nosocomial pathogens able to rapidly develop extensive drug resistance. Here, we study the role of accessory genome in the success of the globally disseminated clone 1 (GC1) with functional and genomic approaches. Comparative genomics was performed with available GC1 genomes (n = 106) against other A. baumannii high-risk and sporadic clones. Genetic traits related to accessory genome were found common and conserved along time as two novel regions of genome plasticity, and a CRISPR-Cas system acquired before clonal diversification located at the same loci as “sedentary” modules. Although identified within hotspot for recombination, other block of accessory genome was also “sedentary” in lineage 1 of GC1 with signs of microevolution as the AbaR0-type genomic island (GI) identified in A144 and in A155 strains which were maintained one month in independent experiments without antimicrobial pressure. The prophage YMC/09/02/B1251_ABA_BP was found to be “mobile” since, although it was shared by all GC1 genomes, it showed high intrinsic microevolution as well as mobility to different insertion sites. Interestingly, a wide variety of Insertion Sequences (IS), probably acquired by the flow of plasmids related to Rep_3 superfamily was found. These IS showed dissimilar genomic location amongst GC1 genomes presumably associated with promptly niche adaptation. On the other hand, a type VI secretion system and three efflux pumps were subjected to deep processes of genomic loss in A. baumannii but not in GC1. As a whole, these findings suggest that preservation of some genetic modules of accessory genome harbored by strains from different continents in combination with great plasticity of IS and varied flow of plasmids, may be central features of the genomic structure of GC1. Competition of A144 and A155 versus A118 (ST 404/ND) without antimicrobial pressure suggested a higher ability of GC1 to grow over a clone with sporadic behavior which explains, from an ecological perspective, the global achievement of this successful pandemic clone in the hospital habitat. Together, these data suggest an essential role of still unknown properties of “mobile” and “sedentary” accessory genome that is preserved over time under different antibiotic or stress conditions.
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Affiliation(s)
- Verónica Elizabeth Álvarez
- Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibióticos, Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - María Paula Quiroga
- Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibióticos, Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - Angélica Viviana Galán
- Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibióticos, Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - Elisabet Vilacoba
- Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibióticos, Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - Cecilia Quiroga
- Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - María Soledad Ramírez
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA, United States
| | - Daniela Centrón
- Laboratorio de Investigaciones en Mecanismos de Resistencia a Antibióticos, Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Buenos Aires, Argentina
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50
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Chiang MH, Yang YS, Sun JR, Wang YC, Kuo SC, Lee YT, Chuang YP, Chen TL. Confronting Tigecycline-Resistant Acinetobacter baumannii via Immunization Against Conserved Resistance Determinants. Front Microbiol 2020; 11:536. [PMID: 32296411 PMCID: PMC7136391 DOI: 10.3389/fmicb.2020.00536] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 03/12/2020] [Indexed: 11/13/2022] Open
Abstract
Antimicrobial-resistant (AMR) bacterial infections, including those caused by Acinetobacter baumannii, have emerged as a clinical crisis worldwide. Immunization with AMR determinants has been suggested as a novel approach to combat AMR bacteria, but has not been validated. The present study targeted tigecycline (TGC) resistance determinants in A. baumannii to test the feasibility of this approach. Using bioinformatic tools, four candidates, AdeA, AdeI, AdeK, and TolC, belonging to the resistance-nodulation-division (RND) efflux pump were identified as highly conserved and exposed antigens from 15 A. baumannii genomes. Antisera generated from recombinant proteins showed the capability to reserve Hoechst 33342, a substrate of the efflux pump, in bacterial cells. The rTolC antisera had the highest complement-dependent killing and opsonophagocytosis effect compared to the sera from phosphate-buffered saline immunized mice. Among the antisera, anti-rAdeK-specific antisera decreased the minimal inhibitory concentration of TGC in 26.7% of the tested isolates. Immunization with rAdeK significantly potentiated TGC efficacy in treating TGC-resistant A. baumannii pneumonia in the murine model. The bacterial load (7.5 × 105 vs. 3.8 × 107, p < 0.01) and neutrophil infiltration in the peri-bronchial vasculature region of immunized mice was significantly lower compared to the PBS-immunized mice when TGC was administrated concomitantly. Collectively, these results suggest that active immunization against resistance determinants might be a feasible approach to combat multidrug-resistant pathogens in high risk population.
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Affiliation(s)
- Ming-Hsien Chiang
- Department and Graduate Institute of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan.,Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Ya-Sung Yang
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Jun-Ren Sun
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Yung-Chih Wang
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Shu-Chen Kuo
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
| | - Yi-Tzu Lee
- School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Department of Emergency Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Yi-Ping Chuang
- Department and Graduate Institute of Microbiology and Immunology, National Defense Medical Center, Taipei, Taiwan
| | - Te-Li Chen
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
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