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Glen KA, Lamont IL. Characterization of acquired β-lactamases in Pseudomonas aeruginosa and quantification of their contributions to resistance. Microbiol Spectr 2024; 12:e0069424. [PMID: 39248479 PMCID: PMC11448201 DOI: 10.1128/spectrum.00694-24] [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] [Received: 03/15/2024] [Accepted: 07/25/2024] [Indexed: 09/10/2024] Open
Abstract
Pseudomonas aeruginosa is a highly problematic opportunistic pathogen that causes a range of different infections. Infections are commonly treated with β-lactam antibiotics, including cephalosporins, monobactams, penicillins, and carbapenems, with carbapenems regarded as antibiotics of last resort. Isolates of P. aeruginosa can contain horizontally acquired bla genes encoding β-lactamase enzymes, but the extent to which these contribute to β-lactam resistance in this species has not been systematically quantified. The overall aim of this research was to address this knowledge gap by quantifying the frequency of β-lactamase-encoding genes in P. aeruginosa and by determining the effects of β-lactamases on susceptibility of P. aeruginosa to β-lactams. Genome analysis showed that β-lactamase-encoding genes are present in 3% of P. aeruginosa but are enriched in carbapenem-resistant isolates (35%). To determine the substrate antibiotics, 10 β-lactamases were expressed from an integrative plasmid in the chromosome of P. aeruginosa reference strain PAO1. The β-lactamases reduced susceptibility to a variety of clinically used antibiotics, including carbapenems (meropenem, imipenem), penicillins (ticarcillin, piperacillin), cephalosporins (ceftazidime, cefepime), and a monobactam (aztreonam). Different enzymes acted on different β-lactams. β-lactamases encoded by the genomes of P. aeruginosa clinical isolates had similar effects to the enzymes expressed in strain PAO1. Genome engineering was used to delete β-lactamase-encoding genes from three carbapenem-resistant clinical isolates and increased susceptibility to substrate β-lactams. Our findings demonstrate that acquired β-lactamases play an important role in β-lactam resistance in P. aeruginosa, identifying substrate antibiotics for a range of enzymes and quantifying their contributions to resistance.IMPORTANCEPseudomonas aeruginosa is an extremely problematic pathogen, with isolates that are resistant to the carbapenem class of β-lactam antibiotics being in critical need of new therapies. Genes encoding β-lactamase enzymes that degrade β-lactam antibiotics can be present in P. aeruginosa, including carbapenem-resistant isolates. Here, we show that β-lactamase genes are over-represented in carbapenem-resistant isolates, indicating their key role in resistance. We also show that different β-lactamases alter susceptibility of P. aeruginosa to different β-lactam antibiotics and quantify the effects of selected enzymes on β-lactam susceptibility. This research significantly advances the understanding of the contributions of acquired β-lactamases to antibiotic resistance, including carbapenem resistance, in P. aeruginosa and by implication in other species. It has potential to expedite development of methods that use whole genome sequencing of infecting bacteria to inform antibiotic treatment, allowing more effective use of antibiotics, and facilitate the development of new antibiotics.
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Affiliation(s)
- Karl A Glen
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Iain L Lamont
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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Resistance Is Not Futile: The Role of Quorum Sensing Plasticity in Pseudomonas aeruginosa Infections and Its Link to Intrinsic Mechanisms of Antibiotic Resistance. Microorganisms 2022; 10:microorganisms10061247. [PMID: 35744765 PMCID: PMC9228389 DOI: 10.3390/microorganisms10061247] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/06/2022] [Accepted: 06/09/2022] [Indexed: 01/01/2023] Open
Abstract
Bacteria use a cell-cell communication process called quorum sensing (QS) to orchestrate collective behaviors. QS relies on the group-wide detection of extracellular signal molecules called autoinducers (AI). Quorum sensing is required for virulence and biofilm formation in the human pathogen Pseudomonas aeruginosa. In P. aeruginosa, LasR and RhlR are homologous LuxR-type soluble transcription factor receptors that bind their cognate AIs and activate the expression of genes encoding functions required for virulence and biofilm formation. While some bacterial signal transduction pathways follow a linear circuit, as phosphoryl groups are passed from one carrier protein to another ultimately resulting in up- or down-regulation of target genes, the QS system in P. aeruginosa is a dense network of receptors and regulators with interconnecting regulatory systems and outputs. Once activated, it is not understood how LasR and RhlR establish their signaling hierarchy, nor is it clear how these pathway connections are regulated, resulting in chronic infection. Here, we reviewed the mechanisms of QS progression as it relates to bacterial pathogenesis and antimicrobial resistance and tolerance.
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β-lactam Resistance in Pseudomonas aeruginosa: Current Status, Future Prospects. Pathogens 2021; 10:pathogens10121638. [PMID: 34959593 PMCID: PMC8706265 DOI: 10.3390/pathogens10121638] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/06/2021] [Accepted: 12/16/2021] [Indexed: 12/12/2022] Open
Abstract
Pseudomonas aeruginosa is a major opportunistic pathogen, causing a wide range of acute and chronic infections. β-lactam antibiotics including penicillins, carbapenems, monobactams, and cephalosporins play a key role in the treatment of P. aeruginosa infections. However, a significant number of isolates of these bacteria are resistant to β-lactams, complicating treatment of infections and leading to worse outcomes for patients. In this review, we summarize studies demonstrating the health and economic impacts associated with β-lactam-resistant P. aeruginosa. We then describe how β-lactams bind to and inhibit P. aeruginosa penicillin-binding proteins that are required for synthesis and remodelling of peptidoglycan. Resistance to β-lactams is multifactorial and can involve changes to a key target protein, penicillin-binding protein 3, that is essential for cell division; reduced uptake or increased efflux of β-lactams; degradation of β-lactam antibiotics by increased expression or altered substrate specificity of an AmpC β-lactamase, or by the acquisition of β-lactamases through horizontal gene transfer; and changes to biofilm formation and metabolism. The current understanding of these mechanisms is discussed. Lastly, important knowledge gaps are identified, and possible strategies for enhancing the effectiveness of β-lactam antibiotics in treating P. aeruginosa infections are considered.
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Impey RE, Hawkins DA, Sutton JM, Soares da Costa TP. Overcoming Intrinsic and Acquired Resistance Mechanisms Associated with the Cell Wall of Gram-Negative Bacteria. Antibiotics (Basel) 2020; 9:E623. [PMID: 32961699 PMCID: PMC7558195 DOI: 10.3390/antibiotics9090623] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/16/2020] [Accepted: 09/17/2020] [Indexed: 12/19/2022] Open
Abstract
The global increase in multi-drug-resistant bacteria is severely impacting our ability to effectively treat common infections. For Gram-negative bacteria, their intrinsic and acquired resistance mechanisms are heightened by their unique cell wall structure. The cell wall, while being a target of some antibiotics, represents a barrier due to the inability of most antibacterial compounds to traverse and reach their intended target. This means that its composition and resulting mechanisms of resistance must be considered when developing new therapies. Here, we discuss potential antibiotic targets within the most well-characterised resistance mechanisms associated with the cell wall in Gram-negative bacteria, including the outer membrane structure, porins and efflux pumps. We also provide a timely update on the current progress of inhibitor development in these areas. Such compounds could represent new avenues for drug discovery as well as adjuvant therapy to help us overcome antibiotic resistance.
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Affiliation(s)
- Rachael E. Impey
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia; (R.E.I.); (D.A.H.)
| | - Daniel A. Hawkins
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia; (R.E.I.); (D.A.H.)
| | - J. Mark Sutton
- National Infection Service, Research and Development Institute, Public Health England, Porton Down, Salisbury, Wiltshire SP4 0JG, UK;
| | - Tatiana P. Soares da Costa
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia; (R.E.I.); (D.A.H.)
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Suresh M, Skariyachan S, Narayanan N, Pullampara Rajamma J, Panickassery Ramakrishnan MK. Mutational Variation Analysis of oprD Porin Gene in Multidrug-Resistant Clinical Isolates of Pseudomonas aeruginosa. Microb Drug Resist 2020; 26:869-879. [PMID: 32083512 DOI: 10.1089/mdr.2019.0147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The present study deals with the outer membrane OprD porin protein in 29 clinical bacterial isolates of multidrug-resistant Pseudomonas aeruginosa. oprD porin gene expression was investigated using real-time reverse transcription-PCR. Amplicons from oprD and its transcriptional regulator mexT gene were sequenced and analyzed for mutations. Hypothetical models of selected mutant OprD-porin proteins were predicted and refined by homology modeling approach. oprD ampliconic sequences were also screened for restriction fragment length polymorphism (RFLP). The oprD gene was found to be downregulated in 89.7% (n = 26) of the isolates in comparison to the transcript levels in the reference strain P. aeruginosa-PAO (MTCC-3541). Interestingly, all these isolates displayed the presence of a conspicuous 8-bp deletion (GGCCAGCC) at nucleotide position 235 of mexT regulatory gene. Based on the mutational patterns observed in oprD gene, the isolates were classified into categories designated as A, B1-2, C1-4, D1-6, E1-2, and F. Our hypothetical models revealed that mutations were predominantly confined to the extracellular loops emanating from the β-barrel porin protein. These protein models also enabled clear visualization of loss of substantial portions of the truncated polypeptide. Incidentally, since most of the oprD amplicons of the clinical isolates were found to display distinct RFLP banding patterns, our results also provide a useful diagnostic tool for detection of P. aeruginosa porin mutants.
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Affiliation(s)
- Manju Suresh
- Department of Biotechnology, University of Calicut, Malappuram, India
| | | | - Nithya Narayanan
- Department of Biotechnology, University of Calicut, Malappuram, India
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Pelegrin AC, Saharman YR, Griffon A, Palmieri M, Mirande C, Karuniawati A, Sedono R, Aditianingsih D, Goessens WHF, van Belkum A, Verbrugh HA, Klaassen CHW, Severin JA. High-Risk International Clones of Carbapenem-Nonsusceptible Pseudomonas aeruginosa Endemic to Indonesian Intensive Care Units: Impact of a Multifaceted Infection Control Intervention Analyzed at the Genomic Level. mBio 2019; 10:e02384-19. [PMID: 31719179 PMCID: PMC6851282 DOI: 10.1128/mbio.02384-19] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 10/04/2019] [Indexed: 12/28/2022] Open
Abstract
Infection control effectiveness evaluations require detailed epidemiological and microbiological data. We analyzed the genomic profiles of carbapenem-nonsusceptible Pseudomonas aeruginosa (CNPA) strains collected from two intensive care units (ICUs) in the national referral hospital in Jakarta, Indonesia, where a multifaceted infection control intervention was applied. We used clinical data combined with whole-genome sequencing (WGS) of systematically collected CNPA to infer the transmission dynamics of CNPA strains and to characterize their resistome. We found that the number of CNPA transmissions and acquisitions by patients was highly variable over time but that, overall, the rates were not significantly reduced by the intervention. Environmental sources were involved in these transmissions and acquisitions. Four high-risk international CNPA clones (ST235, ST823, ST357, and ST446) dominated, but the distribution of these clones changed significantly after the intervention was implemented. Using resistome analysis, carbapenem resistance was explained by the presence of various carbapenemase-encoding genes (blaGES-5, blaVIM-2-8, and blaIMP-1-7-43) and by mutations within the porin OprD. Our results reveal for the first time the dynamics of P. aeruginosa antimicrobial resistance (AMR) profiles in Indonesia and additionally show the utility of WGS in combination with clinical data to evaluate the impact of an infection control intervention. (This study has been registered at www.trialregister.nl under registration no. NTR5541).IMPORTANCE In low-to-middle-income countries such as Indonesia, work in intensive care units (ICUs) can be hampered by lack of resources. Conducting large epidemiological studies in such settings using genomic tools is rather challenging. Still, we were able to systematically study the transmissions of carbapenem-nonsusceptible strains of P. aeruginosa (CNPA) within and between ICUs, before and after an infection control intervention. Our data show the importance of the broad dissemination of the internationally recognized CNPA clones, the relevance of environmental reservoirs, and the mixed effects of the implemented intervention; it led to a profound change in the clonal make-up of CNPA, but it did not reduce the patients' risk of CNPA acquisitions. Thus, CNPA epidemiology in Indonesian ICUs is part of a global expansion of multiple CNPA clones that remains difficult to control by infection prevention measures.
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Affiliation(s)
- Andreu Coello Pelegrin
- Clinical Unit, bioMérieux, La Balme Les Grottes, France
- Vaccine & Infectious Disease Institute, Laboratory of Medical Microbiology, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Yulia Rosa Saharman
- Department of Clinical Microbiology, Faculty of Medicine, Universitas Indonesia/Dr. Cipto Mangunkusumo General Hospital, Jakarta, Indonesia
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | - Mattia Palmieri
- Clinical Unit, bioMérieux, La Balme Les Grottes, France
- Vaccine & Infectious Disease Institute, Laboratory of Medical Microbiology, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | | | - Anis Karuniawati
- Department of Clinical Microbiology, Faculty of Medicine, Universitas Indonesia/Dr. Cipto Mangunkusumo General Hospital, Jakarta, Indonesia
| | - Rudyanto Sedono
- Critical Care Division, Department of Anesthesia and Intensive Care, Faculty of Medicine, Universitas Indonesia/Dr. Cipto Mangunkusumo General Hospital, Jakarta, Indonesia
| | - Dita Aditianingsih
- Critical Care Division, Department of Anesthesia and Intensive Care, Faculty of Medicine, Universitas Indonesia/Dr. Cipto Mangunkusumo General Hospital, Jakarta, Indonesia
| | - Wil H F Goessens
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | - Henri A Verbrugh
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Corné H W Klaassen
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Juliëtte A Severin
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
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Bhamidimarri SP, Zahn M, Prajapati JD, Schleberger C, Söderholm S, Hoover J, West J, Kleinekathöfer U, Bumann D, Winterhalter M, van den Berg B. A Multidisciplinary Approach toward Identification of Antibiotic Scaffolds for Acinetobacter baumannii. Structure 2019; 27:268-280.e6. [DOI: 10.1016/j.str.2018.10.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 08/19/2018] [Accepted: 10/23/2018] [Indexed: 11/16/2022]
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Abstract
Collective antibiotic drug resistance is a global threat, especially with respect to Gram-negative bacteria. The low permeability of the bacterial outer cell wall has been identified as a challenging barrier that prevents a sufficient antibiotic effect to be attained at low doses of the antibiotic. The Gram-negative bacterial cell envelope comprises an outer membrane that delimits the periplasm from the exterior milieu. The crucial mechanisms of antibiotic entry via outer membrane includes general diffusion porins (Omps) responsible for hydrophilic antibiotics and lipid-mediated pathway for hydrophobic antibiotics. The protein and lipid arrangements of the outer membrane have had a strong impact on the understanding of bacteria and their resistance to many types of antibiotics. Thus, one of the current challenges is effective interpretation at the molecular basis of the outer membrane permeability. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in solute influx. Moreover, it aims toward further understanding and exploration of prospects to improve our knowledge of physicochemical limitations that direct the translocation of antibiotics via bacterial outer membrane.
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Affiliation(s)
- Ishan Ghai
- School of Engineering and Life Sciences, Jacobs University, Bremen, Germany.,Consultation Division, RSGBIOGEN, New Delhi, India
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Iyer R, Moussa SH, Durand-Réville TF, Tommasi R, Miller A. Acinetobacter baumannii OmpA Is a Selective Antibiotic Permeant Porin. ACS Infect Dis 2018; 4:373-381. [PMID: 29260856 DOI: 10.1021/acsinfecdis.7b00168] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OmpAAb is a conserved, abundantly expressed outer membrane porin in Acinetobacter baumannii whose presumed role in antibiotic permeation has not been clearly demonstrated. In this report, we use a titratable heterologous expression system to express OmpAAb in isolation and demonstrate selective passage of small molecule antibiotics through OmpAAb. ETX2514, a recently discovered broad-spectrum β-lactamase inhibitor, in combination with sulbactam, is currently in clinical testing for the treatment of drug-resistant A. baumannii infections. We demonstrate that ETX2514 permeates OmpAAb and potentiates the activity of sulbactam in an OmpAAb-dependent manner. In addition, we show that small modifications in the structure of ETX2514 differentially affect its passage through OmpAAb, revealing unique structure-porin-permeation relationships. Finally, we confirm the contribution of OmpAAb to bacterial fitness using a murine thigh model of A. baumannii infection. These results, combined with the high sequence homology of OmpA across Acinetobacter spp., suggest that optimization of antibiotic entry through OmpAAb may prove to be a feasible medicinal chemistry design strategy for future antibacterial discovery efforts.
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Affiliation(s)
- Ramkumar Iyer
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Samir H. Moussa
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | | | - Ruben Tommasi
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Alita Miller
- Entasis Therapeutics, 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
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Iyer R, Sylvester MA, Velez-Vega C, Tommasi R, Durand-Reville TF, Miller AA. Whole-Cell-Based Assay To Evaluate Structure Permeation Relationships for Carbapenem Passage through the Pseudomonas aeruginosa Porin OprD. ACS Infect Dis 2017; 3:310-319. [PMID: 28157293 DOI: 10.1021/acsinfecdis.6b00197] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The global emergence of antibiotic resistance, especially in Gram-negative bacteria, is an urgent threat to public health. Discovery of novel classes of antibiotics with activity against these pathogens has been impeded by a fundamental lack of understanding of the molecular drivers underlying small molecule uptake. Although it is well-known that outer membrane porins represent the main route of entry for small, hydrophilic molecules across the Gram-negative cell envelope, the structure-permeation relationship for porin passage has yet to be defined. To address this knowledge gap, we developed a sensitive and specific whole-cell approach in Escherichia coli called titrable outer membrane permeability assay system (TOMAS). We used TOMAS to characterize the structure porin-permeation relationships of a set of novel carbapenem analogues through the Pseudomonas aeruginosa porin OprD. Our results show that small structural modifications, especially the number and nature of charges and their position, have dramatic effects on the ability of these molecules to permeate cells through OprD. This is the first demonstration of a defined relationship between specific molecular changes in a substrate and permeation through an isolated porin. Understanding the molecular mechanisms that impact antibiotic transit through porins should provide valuable insights to antibacterial medicinal chemistry and may ultimately allow for the rational design of porin-mediated uptake of small molecules into Gram-negative bacteria.
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Affiliation(s)
- Ramkumar Iyer
- Entasis Therapeutics, Inc., 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Mark A. Sylvester
- Entasis Therapeutics, Inc., 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Camilo Velez-Vega
- Entasis Therapeutics, Inc., 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Ruben Tommasi
- Entasis Therapeutics, Inc., 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | | | - Alita A. Miller
- Entasis Therapeutics, Inc., 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
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