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Marino A, Augello E, Stracquadanio S, Bellanca CM, Cosentino F, Spampinato S, Cantarella G, Bernardini R, Stefani S, Cacopardo B, Nunnari G. Unveiling the Secrets of Acinetobacter baumannii: Resistance, Current Treatments, and Future Innovations. Int J Mol Sci 2024; 25:6814. [PMID: 38999924 PMCID: PMC11241693 DOI: 10.3390/ijms25136814] [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: 06/01/2024] [Revised: 06/18/2024] [Accepted: 06/19/2024] [Indexed: 07/14/2024] Open
Abstract
Acinetobacter baumannii represents a significant concern in nosocomial settings, particularly in critically ill patients who are forced to remain in hospital for extended periods. The challenge of managing and preventing this organism is further compounded by its increasing ability to develop resistance due to its extraordinary genomic plasticity, particularly in response to adverse environmental conditions. Its recognition as a significant public health risk has provided a significant impetus for the identification of new therapeutic approaches and infection control strategies. Indeed, currently used antimicrobial agents are gradually losing their efficacy, neutralized by newer and newer mechanisms of bacterial resistance, especially to carbapenem antibiotics. A deep understanding of the underlying molecular mechanisms is urgently needed to shed light on the properties that allow A. baumannii enormous resilience against standard therapies. Among the most promising alternatives under investigation are the combination sulbactam/durlobactam, cefepime/zidebactam, imipenem/funobactam, xeruborbactam, and the newest molecules such as novel polymyxins or zosurabalpin. Furthermore, the potential of phage therapy, as well as deep learning and artificial intelligence, offer a complementary approach that could be particularly useful in cases where traditional strategies fail. The fight against A. baumannii is not confined to the microcosm of microbiological research or hospital wards; instead, it is a broader public health dilemma that demands a coordinated, global response.
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Affiliation(s)
- Andrea Marino
- Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Catania, ARNAS Garibaldi Hospital, 95122 Catania, Italy
| | - Egle Augello
- Department of Biomedical and Biotechnological Science, Section of Pharmacology, University of Catania, 95123 Catania, Italy
- Clinical Toxicology Unit, University Hospital of Catania, 95123 Catania, Italy
| | - Stefano Stracquadanio
- Department of Biomedical and Biotechnological Sciences, Section of Microbiology, University of Catania, Via Santa Sofia 97, 95123 Catania, Italy
| | - Carlo Maria Bellanca
- Department of Biomedical and Biotechnological Science, Section of Pharmacology, University of Catania, 95123 Catania, Italy
- Clinical Toxicology Unit, University Hospital of Catania, 95123 Catania, Italy
| | - Federica Cosentino
- Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Catania, ARNAS Garibaldi Hospital, 95122 Catania, Italy
| | - Serena Spampinato
- Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Catania, ARNAS Garibaldi Hospital, 95122 Catania, Italy
| | - Giuseppina Cantarella
- Department of Biomedical and Biotechnological Science, Section of Pharmacology, University of Catania, 95123 Catania, Italy
| | - Renato Bernardini
- Department of Biomedical and Biotechnological Science, Section of Pharmacology, University of Catania, 95123 Catania, Italy
- Clinical Toxicology Unit, University Hospital of Catania, 95123 Catania, Italy
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences, Section of Microbiology, University of Catania, Via Santa Sofia 97, 95123 Catania, Italy
| | - Bruno Cacopardo
- Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Catania, ARNAS Garibaldi Hospital, 95122 Catania, Italy
| | - Giuseppe Nunnari
- Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Catania, ARNAS Garibaldi Hospital, 95122 Catania, Italy
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Yamada N, Kamoshida G, Shiraishi T, Yamaguchi D, Matsuoka M, Yamauchi R, Kanda N, Kamioka R, Takemoto N, Morita Y, Fujimuro M, Yokota SI, Yahiro K. PmrAB, the two-component system of Acinetobacter baumannii, controls the phosphoethanolamine modification of lipooligosaccharide in response to metal ions. J Bacteriol 2024; 206:e0043523. [PMID: 38661375 PMCID: PMC11112996 DOI: 10.1128/jb.00435-23] [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] [Received: 12/18/2023] [Accepted: 04/03/2024] [Indexed: 04/26/2024] Open
Abstract
Acinetobacter baumannii is highly resistant to antimicrobial agents, and XDR strains have become widespread. A. baumannii has developed resistance to colistin, which is considered the last resort against XDR Gram-negative bacteria, mainly caused by lipooligosaccharide (LOS) phosphoethanolamine (pEtN) and/or galactosamine (GalN) modifications induced by mutations that activate the two-component system (TCS) pmrAB. Although PmrAB of A. baumannii has been recognized as a drug resistance factor, its function as TCS, including its regulatory genes and response factors, has not been fully elucidated. In this study, to clarify the function of PmrAB as TCS, we elucidated the regulatory genes (regulon) of PmrAB via transcriptome analysis using pmrAB-activated mutant strains. We discovered that PmrAB responds to low pH, Fe2+, Zn2+, and Al3+. A. baumannii selectively recognizes Fe2+ rather than Fe3+, and a novel region ExxxE, in addition to the ExxE motif sequence, is involved in the environmental response. Furthermore, PmrAB participates in the phosphoethanolamine modification of LOS on the bacterial surface in response to metal ions such as Al3+, contributing to the attenuation of Al3+ toxicity and development of resistance to colistin and polymyxin B in A. baumannii. This study demonstrates that PmrAB in A. baumannii not only regulates genes that play an important role in drug resistance but is also involved in responses to environmental stimuli such as metal ions and pH, and this stimulation induces LOS modification. This study reveals the importance of PmrAB in the environmental adaptation and antibacterial resistance emergence mechanisms of A. baumannii. IMPORTANCE Antimicrobial resistance (AMR) is a pressing global issue in human health. Acinetobacter baumannii is notably high on the World Health Organization's list of bacteria for which new antimicrobial agents are urgently needed. Colistin is one of the last-resort drugs used against extensively drug-resistant (XDR) Gram-negative bacteria. However, A. baumannii has become increasingly resistant to colistin, primarily by modifying its lipooligosaccharide (LOS) via activating mutations in the two-component system (TCS) PmrAB. This study comprehensively elucidates the detailed mechanism of drug resistance of PmrAB in A. baumannii as well as its biological functions. Understanding the molecular biology of these molecules, which serve as drug resistance factors and are involved in environmental recognition mechanisms in bacteria, is crucial for developing fundamental solutions to the AMR problem.
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Affiliation(s)
- Noriteru Yamada
- Laboratory of Microbiology and Infection Control, Kyoto Pharmaceutical University, Kyoto, Japan
- Laboratory of Cell Biology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Go Kamoshida
- Laboratory of Microbiology and Infection Control, Kyoto Pharmaceutical University, Kyoto, Japan
- Department of Infection Control Science, Meiji Pharmaceutical University, Tokyo, Japan
| | - Tsukasa Shiraishi
- Department of Microbiology, Sapporo Medical University School of Medicine, Hokkaido, Japan
| | - Daiki Yamaguchi
- Laboratory of Microbiology and Infection Control, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Momoko Matsuoka
- Laboratory of Microbiology and Infection Control, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Reika Yamauchi
- Laboratory of Microbiology and Infection Control, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Nana Kanda
- Laboratory of Microbiology and Infection Control, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Roku Kamioka
- Laboratory of Microbiology and Infection Control, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Norihiko Takemoto
- Pathogenic Microbe Laboratory, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Yuji Morita
- Department of Infection Control Science, Meiji Pharmaceutical University, Tokyo, Japan
| | - Masahiro Fujimuro
- Laboratory of Cell Biology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Shin-ichi Yokota
- Department of Microbiology, Sapporo Medical University School of Medicine, Hokkaido, Japan
| | - Kinnosuke Yahiro
- Laboratory of Microbiology and Infection Control, Kyoto Pharmaceutical University, Kyoto, Japan
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Vijayakumar S, Swetha RG, Bakthavatchalam YD, Vasudevan K, Abirami Shankar B, Kirubananthan A, Walia K, Ramaiah S, Biswas I, Veeraraghavan B, Anbarasu A. Genomic investigation unveils colistin resistance mechanism in carbapenem-resistant Acinetobacter baumannii clinical isolates. Microbiol Spectr 2024; 12:e0251123. [PMID: 38214512 PMCID: PMC10846133 DOI: 10.1128/spectrum.02511-23] [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: 06/15/2023] [Accepted: 11/29/2023] [Indexed: 01/13/2024] Open
Abstract
Colistin resistance in Acinetobacter baumannii is mediated by multiple mechanisms. Recently, mutations within pmrABC two-component system and overexpression of eptA gene due to upstream insertion of ISAba1 have been shown to play a major role. Thus, the aim of our study is to characterize colistin resistance mechanisms among the clinical isolates of A. baumannii in India. A total of 207 clinical isolates of A. baumannii collected from 2016 to 2019 were included in this study. Mutations within lipid A biosynthesis and pmrABC genes were characterized by whole-genome shotgun sequencing. Twenty-eight complete genomes were further characterized by hybrid assembly approach to study insertional inactivation of lpx genes and the association of ISAba1-eptA. Several single point mutations (SNPs), like M12I in pmrA, A138T and A444V in pmrB, and E117K in lpxD, were identified. We are the first to report two novel SNPs (T7I and V383I) in the pmrC gene. Among the five colistin-resistant A. baumannii isolates where complete genome was available, the analysis showed that three of the five isolates had ISAba1 insertion upstream of eptA. No mcr genes were identified among the isolates. We mapped the SNPs on the respective protein structures to understand the effect on the protein activity. We found that majority of the SNPs had little effect on the putative protein function; however, some SNPs might destabilize the local structure. Our study highlights the diversity of colistin resistance mechanisms occurring in A. baumannii, and ISAba1-driven eptA overexpression is responsible for colistin resistance among the Indian isolates.IMPORTANCEAcinetobacter baumannii is a Gram-negative, emerging and opportunistic bacterial pathogen that is often associated with a wide range of nosocomial infections. The treatment of these infections is hindered by increase in the occurrence of A. baumannii strains that are resistant to most of the existing antibiotics. The current drug of choice to treat the infection caused by A. baumannii is colistin, but unfortunately, the bacteria started to show resistance to the last-resort antibiotic. The loss of lipopolysaccharides and mutations in lipid A biosynthesis genes are the main reasons for the colistin resistance. The present study characterized 207 A. baumannii clinical isolates and constructed complete genomes of 28 isolates to recognize the mechanisms of colistin resistance. We showed the mutations in the colistin-resistant variants within genes essential for lipid A biosynthesis and that cause these isolates to lose the ability to produce lipopolysaccharides.
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Affiliation(s)
- Saranya Vijayakumar
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Rayapadi G. Swetha
- Medical and Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
| | | | - Karthick Vasudevan
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
- Department of Biotechnology, School of Applied Sciences, REVA University, Bangalore, India
| | - Baby Abirami Shankar
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | | | - Kamini Walia
- Division of Epidemiology and Communicable Diseases, Indian Council for Medical Research, New Delhi, India
| | - Sudha Ramaiah
- Medical and Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas, USA
| | - Balaji Veeraraghavan
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Anand Anbarasu
- Medical and Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
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Stracquadanio S, Nicolosi A, Privitera GF, Massimino M, Marino A, Bongiorno D, Stefani S. Role of transcriptomic and genomic analyses in improving the comprehension of cefiderocol activity in Acinetobacter baumannii. mSphere 2024; 9:e0061723. [PMID: 38078714 PMCID: PMC10826366 DOI: 10.1128/msphere.00617-23] [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] [Received: 10/18/2023] [Accepted: 11/05/2023] [Indexed: 01/31/2024] Open
Abstract
The mechanisms of action and resistance of cefiderocol (FDC) in Acinetobacter baumannii are still not fully elucidated, but iron transport systems have been evoked in its entry into the cell to reach the penicillin-binding proteins (PBPs). To capture the dynamics of gene expression related to FDC action in various conditions, we report on the genomic and transcriptomic features of seven A. baumannii strains with different FDC susceptibility, focusing on the variants in genes associated with β-lactam resistance and the expression of the siderophore biosynthesis and transport systems acinetobactin and baumannoferrin. We also investigated the expression of the TonB energy transduction system (ETS) and siderophore receptors piuA and pirA. The four clinical samples belonged to the same clonal complex (CC2), and the two strains with the highest FDC MICs showed peculiar variants in PBP2 and ampC. Similarly, the two clinical strains with the lowest MICs shared variants in an outer membrane protein as well as ampC. Gene expression analyses highlighted the up-regulation of the acinetobactin and baumannoferrin genes in response to iron depletion and a down-regulation in the presence of high iron concentrations. In response to FDC, gene expression seemed strain-dependent, probably due to the different metabolic features of each strain. Overall, FDC activates the ETS, confirming the active import of the drug; baumannoferrin, more than acinetobactin, appeared stimulated by FDC in an iron-depleted medium. In conclusion, iron transport systems play a clear role in the FDC uptake, and their expression likely contributes to MIC variation together with β-lactam resistance determinants.IMPORTANCEAcinetobacter baumannii poses a threat to healthcare due to its ability to give difficult-to-treat infections as a consequence of our shortage of antibiotic molecules active on this multidrug-resistant bacterium. Cefiderocol (FDC) represents one of the few drugs active on A. baumannii, and to preserve its activity, this study explored the transcriptomic and genomic features of seven strains with varying susceptibility to FDC. Transcriptomic analyses revealed the different effects of FDC on iron transport systems, promoting mainly baumannoferrin expression-thus more likely related to FDC entry-and the energy transduction systems. These findings suggest that not all iron transport systems are equally involved in FDC entry into A. baumannii cells. Finally, mutations in PBPs and β-lactamases may contribute to the resistance onset. Overall, the study sheds light on the importance of iron availability and metabolic differences in FDC resistance, offering insights into understanding the evolution of resistance in A. baumannii strains.
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Affiliation(s)
- Stefano Stracquadanio
- Department of Biomedical and Biotechnological Sciences, Section of Microbiology, University of Catania, Catania, Italy
| | - Alice Nicolosi
- Department of Biomedical and Biotechnological Sciences, Section of Microbiology, University of Catania, Catania, Italy
| | - Grete Francesca Privitera
- Department of Clinical and Experimental Medicine, Unit of Math and Comp Science, University of Catania, Catania, Italy
| | - Mariacristina Massimino
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Andrea Marino
- Department of Clinical and Experimental Medicine, Unit of Infectious Diseases, ARNAS Garibaldi Hospital, University of Catania, Catania, Italy
| | - Dafne Bongiorno
- Department of Biomedical and Biotechnological Sciences, Section of Microbiology, University of Catania, Catania, Italy
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences, Section of Microbiology, University of Catania, Catania, Italy
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Pan Z, Guo J, Zhong Y, Fan L, Su Y. Gentamicin resistance to Escherichia coli related to fatty acid metabolism based on transcriptome analysis. Can J Microbiol 2023; 69:328-338. [PMID: 37224563 DOI: 10.1139/cjm-2023-0036] [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] [Indexed: 05/26/2023]
Abstract
Antibiotic overuse and misuse have promoted the emergence and spread of antibiotic-resistant bacteria. Increasing bacterial resistance to antibiotics is a major healthcare problem, necessitating elucidation of antibiotic resistance mechanisms. In this study, we explored the mechanism of gentamicin resistance by comparing the transcriptomes of antibiotic-sensitive and -resistant Escherichia coli. A total of 410 differentially expressed genes were identified, of which 233 (56.83%) were up-regulated and 177 (43.17%) were down-regulated in the resistant strain compared with the sensitive strain. Gene Ontology (GO) analysis classifies differential gene expression into three main categories: biological processes, cellular components, and molecular functions. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that the up-regulated genes were enriched in eight metabolic pathways, including fatty acid metabolism, which suggests that fatty acid metabolism may be involved in the development of gentamicin resistance in E. coli. This was demonstrated by measuring the acetyl-CoA carboxylase activity, plays a fundamental role in fatty acid metabolism, was increased in gentamicin-resistant E. coli. Treatment of fatty acid synthesis inhibitor, triclosan, promoted gentamicin-mediated killing efficacy to antibiotic-resistant bacteria. We also found that exogenous addition of oleic acid, which involved in fatty acid metabolism, reduced E. coli sensitivity to gentamicin. Overall, our results provide insight into the molecular mechanism of gentamicin resistance development in E. coli.
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Affiliation(s)
- Zhiyu Pan
- Department of Cell Biology & Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, MOE Key Laboratory of Tumor Molecular Biology, Guangdong Provincial Key Laboratory of Bioengineering Medicine, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Juan Guo
- Department of Cell Biology & Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, MOE Key Laboratory of Tumor Molecular Biology, Guangdong Provincial Key Laboratory of Bioengineering Medicine, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Yilin Zhong
- Department of Cell Biology & Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, MOE Key Laboratory of Tumor Molecular Biology, Guangdong Provincial Key Laboratory of Bioengineering Medicine, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Lvyuan Fan
- Department of Cell Biology & Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, MOE Key Laboratory of Tumor Molecular Biology, Guangdong Provincial Key Laboratory of Bioengineering Medicine, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Yubin Su
- Department of Cell Biology & Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, MOE Key Laboratory of Tumor Molecular Biology, Guangdong Provincial Key Laboratory of Bioengineering Medicine, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
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Prasad SV, Fiedoruk K, Zakrzewska M, Savage PB, Bucki R. Glyoxylate Shunt and Pyruvate-to-Acetoin Shift Are Specific Stress Responses Induced by Colistin and Ceragenin CSA-13 in Enterobacter hormaechei ST89. Microbiol Spectr 2023; 11:e0121523. [PMID: 37338344 PMCID: PMC10434160 DOI: 10.1128/spectrum.01215-23] [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] [Received: 03/20/2023] [Accepted: 06/05/2023] [Indexed: 06/21/2023] Open
Abstract
Ceragenins, including CSA-13, are cationic antimicrobials that target the bacterial cell envelope differently than colistin. However, the molecular basis of their action is not fully understood. Here, we examined the genomic and transcriptome responses by Enterobacter hormaechei after prolonged exposure to either CSA-13 or colistin. Resistance of the E. hormaechei 4236 strain (sequence type 89 [ST89]) to colistin and CSA-13 was induced in vitro during serial passages with sublethal doses of tested agents. The genomic and metabolic profiles of the tested isolates were characterized using a combination of whole-genome sequencing (WGS) and transcriptome sequencing (RNA-seq), followed by metabolic mapping of differentially expressed genes using Pathway Tools software. The exposure of E. hormaechei to colistin resulted in the deletion of the mgrB gene, whereas CSA-13 disrupted the genes encoding an outer membrane protein C and transcriptional regulator SmvR. Both compounds upregulated several colistin-resistant genes, such as the arnABCDEF operon and pagE, including genes coding for DedA proteins. The latter proteins, along with beta-barrel protein YfaZ and VirK/YbjX family proteins, were the top overexpressed cell envelope proteins. Furthermore, the l-arginine biosynthesis pathway and putrescine-ornithine antiporter PotE were downregulated in both transcriptomes. In contrast, the expression of two pyruvate transporters (YhjX and YjiY) and genes involved in pyruvate metabolism, as well as genes involved in generating proton motive force (PMF), was antimicrobial specific. Despite the similarity of the cell envelope transcriptomes, distinctly remodeled carbon metabolism (i.e., toward fermentation of pyruvate to acetoin [colistin] and to the glyoxylate pathway [CSA-13]) distinguished both antimicrobials, which possibly reflects the intensity of the stress exerted by both agents. IMPORTANCE Colistin and ceragenins, like CSA-13, are cationic antimicrobials that disrupt the bacterial cell envelope through different mechanisms. Here, we examined the genomic and transcriptome changes in Enterobacter hormaechei ST89, an emerging hospital pathogen, after prolonged exposure to these agents to identify potential resistance mechanisms. Interestingly, we observed downregulation of genes associated with acid stress response as well as distinct dysregulation of genes involved in carbon metabolism, resulting in a switch from pyruvate fermentation to acetoin (colistin) and the glyoxylate pathway (CSA-13). Therefore, we hypothesize that repression of the acid stress response, which alkalinizes cytoplasmic pH and, in turn, suppresses resistance to cationic antimicrobials, could be interpreted as an adaptation that prevents alkalinization of cytoplasmic pH in emergencies induced by colistin and CSA-13. Consequently, this alteration critical for cell physiology must be compensated via remodeling carbon and/or amino acid metabolism to limit acidic by-product production.
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Affiliation(s)
- Suhanya V. Prasad
- Department of Medical Microbiology and Nanobiomedical Engineering, Medical University of Bialystok, Bialystok, Poland
| | - Krzysztof Fiedoruk
- Department of Medical Microbiology and Nanobiomedical Engineering, Medical University of Bialystok, Bialystok, Poland
| | - Magdalena Zakrzewska
- Department of Medical Microbiology and Nanobiomedical Engineering, Medical University of Bialystok, Bialystok, Poland
| | - Paul B. Savage
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah, USA
| | - Robert Bucki
- Department of Medical Microbiology and Nanobiomedical Engineering, Medical University of Bialystok, Bialystok, Poland
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Cavallo I, Oliva A, Pages R, Sivori F, Truglio M, Fabrizio G, Pasqua M, Pimpinelli F, Di Domenico EG. Acinetobacter baumannii in the critically ill: complex infections get complicated. Front Microbiol 2023; 14:1196774. [PMID: 37425994 PMCID: PMC10325864 DOI: 10.3389/fmicb.2023.1196774] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 06/05/2023] [Indexed: 07/11/2023] Open
Abstract
Acinetobacter baumannii is increasingly associated with various epidemics, representing a serious concern due to the broad level of antimicrobial resistance and clinical manifestations. During the last decades, A. baumannii has emerged as a major pathogen in vulnerable and critically ill patients. Bacteremia, pneumonia, urinary tract, and skin and soft tissue infections are the most common presentations of A. baumannii, with attributable mortality rates approaching 35%. Carbapenems have been considered the first choice to treat A. baumannii infections. However, due to the widespread prevalence of carbapenem-resistant A. baumannii (CRAB), colistin represents the main therapeutic option, while the role of the new siderophore cephalosporin cefiderocol still needs to be ascertained. Furthermore, high clinical failure rates have been reported for colistin monotherapy when used to treat CRAB infections. Thus, the most effective antibiotic combination remains disputed. In addition to its ability to develop antibiotic resistance, A. baumannii is also known to form biofilm on medical devices, including central venous catheters or endotracheal tubes. Thus, the worrisome spread of biofilm-producing strains in multidrug-resistant populations of A. baumannii poses a significant treatment challenge. This review provides an updated account of antimicrobial resistance patterns and biofilm-mediated tolerance in A. baumannii infections with a special focus on fragile and critically ill patients.
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Affiliation(s)
- Ilaria Cavallo
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Alessandra Oliva
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy
| | - Rebecca Pages
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Francesca Sivori
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Mauro Truglio
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Giorgia Fabrizio
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Martina Pasqua
- Department of Biology and Biotechnology "C. Darwin" Sapienza University of Rome, Rome, Italy
| | - Fulvia Pimpinelli
- Microbiology and Virology, San Gallicano Dermatological Institute, IRCCS, Rome, Italy
| | - Enea Gino Di Domenico
- Department of Biology and Biotechnology "C. Darwin" Sapienza University of Rome, Rome, Italy
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Firoozeh F, Nikibakhsh M, Badmasti F, Zibaei M, Nikbin VS. Clonal relatedness of carbapenem-resistant Acinetobacter baumannii: high prevalence of ST136 pas in a burn center. Ann Clin Microbiol Antimicrob 2023; 22:34. [PMID: 37149598 PMCID: PMC10164327 DOI: 10.1186/s12941-023-00589-9] [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: 04/09/2022] [Accepted: 04/27/2023] [Indexed: 05/08/2023] Open
Abstract
BACKGROUND Carbapenem-resistant Acinetobacter baumannii (CRAB) is a global health crisis. This study aimed to determine the clonal relatedness of antibiotic-resistant A. baumannii isolates in hospitalized patients who suffered from burn wound infection. METHODS One hundred and six A. baumannii isolates from 562 patients with burn wound infections, were identified and examined for antimicrobial susceptibility. Detection and characterization of carbapenem-hydrolyzing class D OXA-type beta-lactamases (CHDLs) were performed by PCR assays. The clonal relatedness of A. baumannii isolates was determined by multilocus sequence typing (MLST) according to the Pasteur scheme, dual-sequence typing of blaOXA-51-like and ampC genes, and RAPD-PCR method. RESULTS All isolates were carbapenem-resistant while susceptible to colistin, minocycline, doxycycline, and ampicillin-sulbactam. The intrinsic blaOXA-51-like was detected in all isolates, and blaOXA-23-like was identified in 92.5% of isolates. However, blaOXA-143-like and blaOXA-58-like genes were not detected among isolates. Four distinct blaOXA-51-like alleles were determined as follows: blaOXA-317 (67.0%), blaOXA-90 (9.4%), blaOXA-69 (17.0%), and blaOXA-64 (6.6%) and four ampC (blaADC) allele types including ampC-25 (6.6%), ampC-39 (9.4%), ampC-1 (17.0%), and blaADC-88 (67.0%) were identified. MLST (Pasteur scheme) analysis revealed four ST types including ST136 (singleton), ST1 (CC1), ST25 (CC25), and ST78 (singleton) in 71, 18, 7, and 10 of A. baumannii strains, respectively. Five RAPD clusters including A (1.9%), B (26.4%), C (57.5%), D (7.5%), and E (1.9%) were characterized and 5 (4.7%) strains were found to be singletons. CONCLUSION The present study demonstrated that there was a high prevalence of blaOXA-23-like producing CRAB in the clinical setting. The majority of isolates belonged to ST136 (singleton). However, blaOXA-23-like producing multi-drug resistant international clones including ST1, and emerging lineages (e.g. ST25 and ST78) were also identified. Interestingly, in this study ST2 was not detected.
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Affiliation(s)
- Farzaneh Firoozeh
- Department of Microbiology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
- Evidence-based Phytotherapy and Complementary Medicine Research Center, Alborz University of Medical Sciences, Karaj, Iran
| | - Mahnaz Nikibakhsh
- Department of Microbiology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
| | - Farzad Badmasti
- Department of Bacteriology, Pasteur Institute of Iran, Tehran, Iran.
| | - Mohammad Zibaei
- Department of Parasitology and Mycology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
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9
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Colistin Resistance in Acinetobacter baumannii: Molecular Mechanisms and Epidemiology. Antibiotics (Basel) 2023; 12:antibiotics12030516. [PMID: 36978383 PMCID: PMC10044110 DOI: 10.3390/antibiotics12030516] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/17/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Acinetobacter baumannii is recognized as a clinically significant pathogen causing a wide spectrum of nosocomial infections. Colistin was considered a last-resort antibiotic for the treatment of infections caused by multidrug-resistant A. baumannii. Since the reintroduction of colistin, a number of mechanisms of colistin resistance in A. baumannii have been reported, including complete loss of LPS by inactivation of the biosynthetic pathway, modifications of target LPS driven by the addition of phosphoethanolamine (PEtN) moieties to lipid A mediated by the chromosomal pmrCAB operon and eptA gene-encoded enzymes or plasmid-encoded mcr genes and efflux of colistin from the cell. In addition to resistance to colistin, widespread heteroresistance is another feature of A. baumannii that leads to colistin treatment failure. This review aims to present a critical assessment of relevant published (>50 experimental papers) up-to-date knowledge on the molecular mechanisms of colistin resistance in A. baumannii with a detailed review of implicated mutations and the global distribution of colistin-resistant strains.
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10
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Lai SJ, Tu IF, Tseng TS, Tsai YH, Wu SH. The deficiency of poly-β-1,6-N-acetyl-glucosamine deacetylase trigger A. baumannii to convert to biofilm-independent colistin-tolerant cells. Sci Rep 2023; 13:2800. [PMID: 36797306 PMCID: PMC9935895 DOI: 10.1038/s41598-023-30065-5] [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: 11/02/2022] [Accepted: 02/15/2023] [Indexed: 02/18/2023] Open
Abstract
Acinetobacter baumannii is a nosocomial pathogen that can be resistant to antibiotics by rapidly modulating its anti-drug mechanisms. The multidrug-resistant A. baumannii has been considered one of the most threatening pathogens to our society. Biofilm formation and persistent cells within the biofilm matrix are recognized as intractable problems, especially in hospital-acquired infections. Poly-β-1,6-N-acetyl-glucosamine (PNAG) is one of the important building blocks in A. baumannii's biofilm. Here, we discover a protein phosphoryl-regulation on PNAG deacetylase, AbPgaB1, in which residue Ser411 was phosphorylated. The phosphoryl-regulation on AbPgaB1 modulates the product turnover rate in which deacetylated PNAG is produced and reflected in biofilm production. We further uncovered the PgaB deficient A. baumannii strain shows the lowest level of biofilm production but has a high minimal inhibition concentration to antibiotic colistin and tetracycline. Based on bactericidal post-antibiotic effects and time-dependent killing assays with antibacterial drugs, we claim that the PgaB-deficient A. baumannii converts to colistin-tolerant cells. This study utilizes a biofilm-independent colistin-tolerant model of A. baumannii to further investigate its characteristics and mechanisms to better understand clinical outcomes.
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Affiliation(s)
- Shu-Jung Lai
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung, 404333, Taiwan. .,Research Center for Cancer Biology, China Medical University, Taichung, 404333, Taiwan.
| | - I-Fan Tu
- grid.28665.3f0000 0001 2287 1366Institute of Biological Chemistry, Academia Sinica, Taipei, 11529 Taiwan
| | - Tien-Sheng Tseng
- grid.260542.70000 0004 0532 3749Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan
| | - Yu-Hsuan Tsai
- grid.510951.90000 0004 7775 6738Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, 518132 China
| | - Shih-Hsiung Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan. .,Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan.
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11
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Editorial on the Research Topic of the Special Issue "Current Status of Acinetobacter Infections". Pathogens 2023; 12:pathogens12020219. [PMID: 36839491 PMCID: PMC9960586 DOI: 10.3390/pathogens12020219] [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: 01/26/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
Emerging bacterial infections will continue to be an important issue for public health, mostly because of the constant changes on our earth [...].
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12
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Sharma J, Sharma D, Singh A, Sunita K. Colistin Resistance and Management of Drug Resistant Infections. THE CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY = JOURNAL CANADIEN DES MALADIES INFECTIEUSES ET DE LA MICROBIOLOGIE MEDICALE 2022; 2022:4315030. [PMID: 36536900 PMCID: PMC9759378 DOI: 10.1155/2022/4315030] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 11/21/2022] [Accepted: 12/01/2022] [Indexed: 09/19/2023]
Abstract
Colistin resistance is a globalized sensible issue because it has been considered a drug of the last-line resort to treat drug-resistant bacterial infections. The product of the mobilized colistin resistance (mcr) gene and its variants are the significant causes of colistin resistance, which is emerging due to the frequent colistin use in veterinary, and these genes circulate among the bacterial community. Apart from mcr genes, some other intrinsic genes and proteins are also involved in colistin resistance. Researchers focus on the most advanced genomics (whole genome sequencing), proteomics, and bioinformatics approaches to explore the question of colistin resistance. To combat colistin resistance, researchers developed various strategies such as the development of newer drugs, the repurposing of existing drugs, combinatorial treatment by colistin with other drugs, a nano-based approach, photodynamic therapy, a CRISPRi-based strategy, and a phage-based strategy. In this timeline review, we have discussed the development of colistin resistance and its management in developing countries.
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Affiliation(s)
- Juhi Sharma
- School of Life Science, Jaipur National University, Jaipur, India
| | - Divakar Sharma
- Department of Microbiology, Maulana Azad Medical College, Delhi, India
- Department of Microbiology, Lady Hardinge Medical College, Delhi, India
| | - Amit Singh
- Department of Gastroenterology and Human Nutrition, All India Institute of Medical Sciences, Delhi, India
- Department of Microbiology, Central University of Punjab, Bathinda, India
| | - Kumari Sunita
- Department of Botany, Deen Dayal Upadhyay Gorakhpur University, Gorakhpur, Uttar Pradesh, India
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13
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Assessment of the Susceptibility of Clinical Gram-Negative and Gram-Positive Bacterial Strains to Fosfomycin and Significance of This Antibiotic in Infection Treatment. Pathogens 2022; 11:pathogens11121441. [PMID: 36558775 PMCID: PMC9786176 DOI: 10.3390/pathogens11121441] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/24/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022] Open
Abstract
Multidrug resistance of bacteria has prompted intensive development work on new medicines, but also the search for effective options among the oldest antibiotics. Although intravenous fosfomycin (IVFOS) seems to be an interesting proposal, the recommended agar dilution method for susceptibility determination poses a major problem in routine diagnostic testing. As a consequence, there is a lack of comprehensive data on the frequency of isolation of susceptible or resistant strains. This fact triggered the disposition of EUCAST concerning the revision of IVFOS breakpoints (BPs), including withdrawal of BPs for Enterobacterales (excluding E. coli) and coagulase-negative staphylococci. Therefore, the aim of this study was to assess the activity of fosfomycin against numerous clinical strains using recommended methods. Materials and methods: A total of 997 bacterial strains were tested from the following genera: Enterobacterales, Pseudomonas spp., Staphylococcus spp., Acinetobacter spp., and Enterococcus spp., for which there are currently no BPs. The strains were isolated from various clinical materials from patients hospitalized in five hospitals. During the investigation, the recommended agar dilution method was used. Susceptibility to other antibiotics and resistance mechanisms were determined using an automatic method (Phoenix) the disk diffusion method, and E-tests. MIC values of fosfomycin were estimated for all strains and for susceptible and multidrug-resistant (MDR) strains individually. Results: Except for Acinetobacter and Enterococcus, 83% of the strains were susceptible to IVFOS, including the largest percentage of S. aureus and E. coli. Klebsiella spp. turned out to be the least susceptible strains (66%). The highest proportion of susceptibility to fosfomycin was found among strains that were sensitive to other antibiotics (80.9%), and the lowest was found among Gram-negative carbapenemase-producing bacteria (55.6%) and ESBL+ bacteria (61.6%). The MIC evaluation revealed the lowest MIC50 and MIC90 values for S. aureus (0.5 mg/L and 1 mg/L, respectively) and E. coli (4 mg/L and 32 mg/L, respectively). The highest values of MIC50 were found for Acinetobacter spp. (256 mg/L), while the highest values of MIC90 were found for Acinetobacter spp. and Klebsiella spp. (256 mg/L and 512 mg/L, respectively). Conclusions: IVFOS appears to be suitable for the treatment of many infections, including the empirical treatment of polymicrobial infections and those caused by MDR strains, since the sensitivity of the studied strains to this antibiotic in different groups ranged from 66% to as much as 99%. Sensitivity to fosfomycin was also demonstrated by 60% of carbapenem-resistant strains; therefore, IVFOS is one of the few therapeutic options that can be effective against the most resistant Gram-negative rods. In light of the general consultation posted by EUCAST, obtaining data such as IVFOS MIC value distributions may be vital for the decision of implementing fosfomycin into breakpoint tables.
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14
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Ušjak D, Novović K, Filipić B, Kojić M, Filipović N, Stevanović MM, Milenković MT. In vitro colistin susceptibility of pandrug-resistant Acinetobacter baumannii is restored in the presence of selenium nanoparticles. J Appl Microbiol 2022; 133:1197-1206. [PMID: 35612566 DOI: 10.1111/jam.15638] [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: 11/08/2021] [Revised: 02/23/2022] [Accepted: 05/19/2022] [Indexed: 11/30/2022]
Abstract
AIMS To investigate the synergistic activity of colistin and selenium nanoparticles (SeNPs) against pandrug-resistant (PDR) Acinetobacter baumannii. METHODS AND RESULTS Chequerboard and time-kill assays were employed to explore the potential synergistic interactions between colistin and SeNPs against A. baumannii isolates (8), previously determined as colistin-resistant (MIC range 16-256 μg ml-1 ). Also, whole-genome sequencing (WGS) and gene expression analyses were used to elucidate the mechanisms of colistin resistance. Exceptionally strong synergistic activity (FICI range 0.004-0.035) of colistin and SeNPs against colistin-resistant isolates was revealed. Colistin (0.5 or 1 μg ml-1 ) used in combination with SeNPs (0.5 μg ml-1 ) was able to reduce initial inoculum during the first 4 h of incubation, in contrast to colistin (0.5, 1 or 2 μg ml-1 ) alone. CONCLUSIONS These findings propose colistin/SeNPs combination as a new option to fight PDR A. baumannii, the therapeutic possibilities of which should be proved in future in vivo studies. SIGNIFICANCE AND IMPACT OF STUDY Here we present the first evidence of synergy between colistin and selenium compounds against bacteria in general. Also, WGS and gene expression analyses provide some new insights into A. baumannii colistin resistance mechanisms.
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Affiliation(s)
- Dušan Ušjak
- Department of Microbiology and Immunology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Katarina Novović
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia
| | - Brankica Filipić
- Department of Microbiology and Immunology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia.,Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia
| | - Milan Kojić
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia
| | - Nenad Filipović
- Institute of Technical Sciences of the Serbian Academy of Sciences and Arts, Belgrade, Serbia
| | - Magdalena M Stevanović
- Institute of Technical Sciences of the Serbian Academy of Sciences and Arts, Belgrade, Serbia
| | - Marina T Milenković
- Department of Microbiology and Immunology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
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15
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Kang M, Kim W, Lee J, Jung HS, Jeon CO, Park W. 6-Bromo-2-naphthol from Silene armeria extract sensitizes Acinetobacter baumannii strains to polymyxin. Sci Rep 2022; 12:8546. [PMID: 35595766 PMCID: PMC9123208 DOI: 10.1038/s41598-022-11995-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 05/04/2022] [Indexed: 12/02/2022] Open
Abstract
The overuse of antibiotics has led to the emergence of multidrug-resistant bacteria, which are resistant to various antibiotics. Combination therapies using natural compounds with antibiotics have been found to have synergistic effects against several pathogens. Synergistic natural compounds can potentiate the effects of polymyxins for the treatment of Acinetobacter baumannii infection. Out of 120 types of plant extracts, only Silene armeria extract (SAE) showed a synergistic effect with polymyxin B (PMB) in our fractional inhibitory concentration and time-kill analyses. The survival rate of G. mellonella infected with A. baumannii ATCC 17978 increased following the synergistic treatment. Interestingly, the addition of osmolytes, such as trehalose, canceled the synergistic effect of SAE with PMB; however, the underlying mechanism remains unclear. Quadrupole time-of-flight liquid chromatography-mass spectrometry revealed 6-bromo-2-naphthol (6B2N) to be a major active compound that exhibited synergistic effects with PMB. Pretreatment with 6B2N made A. baumannii cells more susceptible to PMB exposure in a time- and concentration-dependent manner, indicating that 6B2N exhibits consequential synergistic action with PMB. Moreover, the exposure of 6B2N-treated cells to PMB led to higher membrane leakage and permeability. The present findings provide a promising approach for utilizing plant extracts as adjuvants to reduce the toxicity of PMB in A. baumannii infection.
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Affiliation(s)
- Mingyeong Kang
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Wonjae Kim
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Jaebok Lee
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Hye Su Jung
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Che Ok Jeon
- Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Woojun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea.
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16
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Torres DA, Seth-Smith HMB, Joosse N, Lang C, Dubuis O, Nüesch-Inderbinen M, Hinic V, Egli A. Colistin resistance in Gram-negative bacteria analysed by five phenotypic assays and inference of the underlying genomic mechanisms. BMC Microbiol 2021; 21:321. [PMID: 34798825 PMCID: PMC8605564 DOI: 10.1186/s12866-021-02388-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 11/09/2021] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Colistin is used against multi-drug resistant pathogens, yet resistance emerges through dissemination of plasmid-mediated genes (mcr) or chromosomal mutation of genes involved in lipopolysaccharide synthesis (i.e. mgrB, phoPQ, pmrCAB). Phenotypic susceptibility testing is challenging due to poor diffusion of colistin in agar media, leading to an underestimation of resistance. Performance of five phenotypic approaches was compared in the context of different molecular mechanisms of resistance. We evaluated Vitek 2® (bioMérieux, AST N242), Colistin MIC Test Strip (Liofilchem Diagnostici), UMIC (Biocentric), and Rapid Polymyxin™ NP test (ELITechGroup) against the standard broth microdilution (BMD) method. We used whole genome sequencing (WGS) to infer molecular resistance mechanisms. We analysed 97 Enterobacterales and non-fermenting bacterial isolates, largely clinical isolates collected up to 2018. Data was analysed by comparing susceptibility categories (susceptible or resistant) and minimal inhibitory concentrations (MIC). Susceptibility category concordance is the percentage of test results sharing the same category to BMD. MIC concordance was calculated similarly but considering ±1 MIC titre error range. We determined genomic diversity by core genome multi locus sequencing typing (cgMLST) and identified putative antimicrobial resistance genes using NCBI and CARD databases, and manual annotation. RESULTS Of 97 isolates, 54 (56%) were resistant with standard BMD. Highest susceptibility category concordance was achieved by Rapid Polymyxin™ NP (98.8%) followed by UMIC (97.9%), Colistin E-test MIC strip (96.9%) and Vitek 2® (95.6%). Highest MIC concordance was achieved by UMIC (80.4%), followed by Vitek 2® (72.5%) and Colistin E-test MIC strip (62.9%). Among resistant isolates, 23/54 (43%) were intrinsically resistant to colistin, whereas 31/54 (57%) isolates had acquired colistin resistance. Of these, mcr-1 was detected in four isolates and mcr-2 in one isolate. Non-synonymous mutations in mgrB, phoQ, pmrA, pmrB, and pmrC genes were encountered in Klebsiella pneumoniae, Escherichia coli, and Acinetobacter bereziniae resistant isolates. Mutations found in mgrB and pmrB were only identified in isolates exhibiting MICs of ≥16 mg/L. CONCLUSIONS The Rapid Polymyxin™ NP test showed highest categorical concordance and the UMIC test provided MIC values with high concordance to BMD. We found colistin resistance in diverse species occurred predominantly through spontaneous chromosomal mutation rather than plasmid-mediated resistance.
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Affiliation(s)
- Diana Albertos Torres
- Applied Microbiology Research, Department of Biomedicine, University of Basel, Basel, Switzerland
- Clinical Bacteriology and Mycology, University Hospital Basel, Basel, Switzerland
| | - Helena M B Seth-Smith
- Applied Microbiology Research, Department of Biomedicine, University of Basel, Basel, Switzerland
- Clinical Bacteriology and Mycology, University Hospital Basel, Basel, Switzerland
| | - Nicole Joosse
- Clinical Bacteriology and Mycology, University Hospital Basel, Basel, Switzerland
- Unilabs Bern-Mittelland, Bern, Switzerland
| | - Claudia Lang
- Clinical Microbiology, Viollier AG, Allschwil, Switzerland
| | - Olivier Dubuis
- Clinical Microbiology, Viollier AG, Allschwil, Switzerland
| | | | - Vladimira Hinic
- Clinical Bacteriology and Mycology, University Hospital Basel, Basel, Switzerland
| | - Adrian Egli
- Applied Microbiology Research, Department of Biomedicine, University of Basel, Basel, Switzerland.
- Clinical Bacteriology and Mycology, University Hospital Basel, Basel, Switzerland.
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17
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Colistin Resistance Onset Strategies and Genomic Mosaicism in Clinical Acinetobacter baumannii Lineages. Pathogens 2021; 10:pathogens10111516. [PMID: 34832671 PMCID: PMC8623500 DOI: 10.3390/pathogens10111516] [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: 10/20/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 11/16/2022] Open
Abstract
The treatment of multidrug-resistant Gram-negative infections is based on colistin. As result, COL-resistance (COL-R) can develop and spread. In Acinetobacter baumannii, a crucial step is to understand COL-R onset and stability, still far to be elucidated. COL-R phenotypic stability, onset modalities, and phylogenomics were investigated in a clinical A. baumannii sample showing a COL resistant (COLR) phenotype at first isolation. COL-R was confirmed by Minimum-Inhibitory-Concentrations as well as investigated by Resistance-Induction assays and Population-Analysis-Profiles (PAPs) to determine: (i) stability; (ii) inducibility; (iii) heteroresistance. Genomics was performed by Mi-Seq Whole-Genome-Sequencing, Phylogenesis, and Genomic Epidemiology by bioinformatics. COLRA. baumannii were subdivided as follows: (i) 3 A. baumannii with stable and high COL MICs defining the “homogeneous-resistant” onset phenotype; (ii) 6 A. baumannii with variable and lower COL MICs displaying a “COL-inducible” onset phenotype responsible for adaptive-resistance or a “subpopulation” onset phenotype responsible for COL-heteroresistance. COL-R stability and onset strategies were not uniquely linked to the amount of LPS and cell envelope charge. Phylogenomics categorized 3 lineages clustering stable and/or unstable COL-R phenotypes with increasing genomic complexity. Likewise, different nsSNP profiling in genes already associated with COL-R marked the stable and/or unstable COL-R phenotypes. Our investigation finds out that A. baumannii can range through unstable or stable COLR phenotypes emerging via different “onset strategies” within phylogenetic lineages displaying increasing genomic mosaicism.
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An Outbreak of tet(X6)-Carrying Tigecycline-Resistant Acinetobacter baumannii Isolates with a New Capsular Type at a Hospital in Taiwan. Antibiotics (Basel) 2021; 10:antibiotics10101239. [PMID: 34680819 PMCID: PMC8532604 DOI: 10.3390/antibiotics10101239] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/06/2021] [Accepted: 10/08/2021] [Indexed: 11/21/2022] Open
Abstract
Dissemination of multidrug-resistant, particularly tigecycline-resistant, Acinetobacter baumannii is of critical importance, as tigecycline is considered a last-line antibiotic. Acquisition of tet(X), a tigecycline-inactivating enzyme mostly found in strains of animal origin, imparts tigecycline resistance to A. baumannii. Herein, we investigated the presence of tet(X) variants among 228 tigecycline-non-susceptible A. baumannii isolates from patients at a Taiwanese hospital via polymerase chain reaction using a newly designed universal primer pair. Seven strains (3%) carrying tet(X)-like genes were subjected to whole genome sequencing, revealing high DNA identity. Phylogenetic analysis based on the PFGE profile clustered the seven strains in a clade, which were thus considered outbreak strains. These strains, which were found to co-harbor the chromosome-encoded tet(X6) and the plasmid-encoded blaOXA-72 genes, showed a distinct genotype with an uncommon sequence type (Oxford ST793/Pasteur ST723) and a new capsular type (KL129). In conclusion, we identified an outbreak clone co-carrying tet(X6) and blaOXA-72 among a group of clinical A. baumannii isolates in Taiwan. To the best of our knowledge, this is the first description of tet(X6) in humans and the first report of a tet(X)-like gene in Taiwan. These findings identify the risk for the spread of tet(X6)-carrying tigecycline- and carbapenem-resistant A. baumannii in human healthcare settings.
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Various Novel Colistin Resistance Mechanisms Interact To Facilitate Adaptation of Aeromonas hydrophila to Complex Colistin Environments. Antimicrob Agents Chemother 2021; 65:e0007121. [PMID: 33903105 PMCID: PMC8373241 DOI: 10.1128/aac.00071-21] [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: 12/13/2022] Open
Abstract
Aeromonas hydrophila, a heterotrophic and Gram-negative bacterium, has attracted considerable attention owing to the increasing prevalence of reported infections. Colistin is a last-resort antibiotic that can treat life-threatening infections caused by multidrug-resistant Gram-negative bacteria. However, the mechanisms underlying colistin resistance in A. hydrophila remain unclear. The present study reveals four novel colistin resistance mechanisms in A. hydrophila: (i) EnvZ/OmpR upregulates the expression of the arnBCADTEF operon to mediate lipopolysaccharide (LPS) modification by 4-amino-4-deoxy-l-arabinose, (ii) EnvZ/OmpR regulates the expression of the autotransporter gene3832 to decrease outer membrane permeability in response to colistin, (iii) deletion of envZ/ompR activates PhoP/PhoQ, which functions as a substitute two-component system to mediate the addition of phosphoethanolamine to lipid A via pmrC, and (iv) the mlaFD173A mutant confers high-level colistin resistance via upregulation of the Mla pathway. The EnvZ/OmpR two-component system-mediated resistance mechanism is the leading form of colistin resistance in A. hydrophila, which enables it to rapidly generate low- to medium-level colistin resistance. As colistin concentrations in the environment continue to rise, antibiotic resistance mediated by EnvZ/OmpR becomes insufficient to ensure bacterial survival. Consequently, A. hydrophila has developed an mlaF mutation that results in high-level colistin resistance. Our findings indicate that A. hydrophila can thrive in a complex environment through various colistin resistance mechanisms.
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Ilsan NA, Lee YJ, Kuo SC, Lee IH, Huang TW. Antimicrobial Resistance Mechanisms and Virulence of Colistin- and Carbapenem-Resistant Acinetobacter baumannii Isolated from a Teaching Hospital in Taiwan. Microorganisms 2021; 9:microorganisms9061295. [PMID: 34198665 PMCID: PMC8232278 DOI: 10.3390/microorganisms9061295] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 01/01/2023] Open
Abstract
Acinetobacter baumannii, a Gram-negative bacterium, is an important nosocomial pathogen. Colistin-resistant A. baumannii is becoming a new concern, since colistin is one of the last-line antibiotics for infections by carbapenem-resistant A. baumannii. From 452 carbapenem-resistant isolates collected in a teaching hospital in Taipei, Taiwan, we identified seven that were resistant to colistin. Carbapenem resistance in these isolates is attributed to the presence of carbapenemase gene blaOXA-23 in their genomes. Colistin resistance is presumably conferred by mutations in the sensor kinase domain of PmrB found in these isolates, which are known to result in modification of colistin target lipid A via the PmrB-PmrA-PmrC signal transduction pathway. Overexpression of pmrC, eptA, and naxD was observed in all seven isolates. Colistin resistance mediated by pmrB mutations has never been reported in Taiwan. One of the seven isolates contained three mutations in lpxD and exhibited an altered lipopolysaccharide profile, which may contribute to its colistin resistance. No significant difference in growth rates was observed between the isolates and the reference strain, suggesting no fitness cost of colistin resistance. Biofilm formation abilities of the isolates were lower than that of the reference. Interestingly, one of the isolates was heteroresistant to colistin. Four of the isolates were significantly more virulent to wax moth larvae than the reference.
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Affiliation(s)
- Noor Andryan Ilsan
- International Master/Ph.D. Program in Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
| | - Yuarn-Jang Lee
- Department of Internal Medicine, Division of Infectious Diseases, Taipei Medical University Hospital, Taipei 11031, Taiwan;
- Department of Internal Medicine, Division of Infectious Diseases, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
| | - Shu-Chen Kuo
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan 35053, Taiwan;
| | - I-Hui Lee
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
| | - Tzu-Wen Huang
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
- Correspondence: ; Tel./Fax: +886-2-2736-1661 (ext. 3925); (ext. 3921)
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Tao Y, Acket S, Beaumont E, Galez H, Duma L, Rossez Y. Colistin Treatment Affects Lipid Composition of Acinetobacter baumannii. Antibiotics (Basel) 2021; 10:antibiotics10050528. [PMID: 34063718 PMCID: PMC8147793 DOI: 10.3390/antibiotics10050528] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 04/30/2021] [Accepted: 05/01/2021] [Indexed: 12/15/2022] Open
Abstract
Multidrug-resistant Acinetobacter baumannii (A. baumannii) causes severe and often fatal healthcare-associated infections due partly to antibiotic resistance. There are no studies on A. baumannii lipidomics of susceptible and resistant strains grown at lethal and sublethal concentrations. Therefore, we analyzed the impact of colistin resistance on glycerolipids’ content by using untargeted lipidomics on clinical isolate. Nine lipid sub-classes were annotated, including phosphatidylcholine, rarely detected in the bacterial membrane among 130 different lipid species. The other lipid sub-classes detected are phosphatidylethanolamine (PE), phosphatidylglycerol (PG), lysophosphatidylethanolamine, hemibismonoacylglycerophosphate, cardiolipin, monolysocardiolipin, diacylglycerol, and triacylglycerol. Under lethal and sublethal concentrations of colistin, significant reduction of PE was observed on the resistant and susceptible strain, respectively. Palmitic acid percentage was higher at colistin at low concentration but only for the susceptible strain. When looking at individual lipid species, the most abundant PE and PG species (PE 34:1 and PG 34:1) are significantly upregulated when the susceptible and the resistant strains are cultivated with colistin. This is, to date, the most exhaustive lipidomics data compilation of A. baumannii cultivated in the presence of colistin. This work is highlighting the plasma membrane plasticity used by this gram-negative bacterium to survive colistin treatment.
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22
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Shropshire H, Jones RA, Aguilo-Ferretjans MM, Scanlan DJ, Chen Y. Proteomics insights into the Burkholderia cenocepacia phosphorus stress response. Environ Microbiol 2021; 23:5069-5086. [PMID: 33684254 DOI: 10.1111/1462-2920.15451] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 03/02/2021] [Indexed: 11/26/2022]
Abstract
The Burkholderia cepacia complex is a group of Burkholderia species that are opportunistic pathogens causing high mortality rates in patients with cystic fibrosis. An environmental stress often encountered by these soil-dwelling and pathogenic bacteria is phosphorus limitation, an essential element for cellular processes. Here, we describe cellular and extracellular proteins differentially regulated between phosphate-deplete (0 mM, no added phosphate) and phosphate-replete (1 mM) growth conditions using a comparative proteomics (LC-MS/MS) approach. We observed a total of 128 and 65 unique proteins were downregulated and upregulated respectively, in the B. cenocepacia proteome. Of those downregulated proteins, many have functions in amino acid transport/metabolism. We have identified 24 upregulated proteins that are directly/indirectly involved in inorganic phosphate or organic phosphorus acquisition. Also, proteins involved in virulence and antimicrobial resistance were differentially regulated, suggesting B. cenocepacia experiences a dramatic shift in metabolism under these stress conditions. Overall, this study provides a baseline for further research into the biology of Burkholderia in response to phosphorus stress.
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Affiliation(s)
- Holly Shropshire
- BBSRC Midlands Integrative Biosciences Training Partnership, University of Warwick, Coventry, CV4 7AL, UK.,School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Rebekah A Jones
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | | | - David J Scanlan
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Yin Chen
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
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23
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Cafiso V, Lo Verde F, Zega A, Pigola G, Rostagno R, Borrè S, Stefani S. Genomic Characterization of a New Biofilm-Forming and Adhesive ST398 Human-Adapted MSSA Lineage Causing Septic Knee Arthritis Following Surgical Reconstruction. Microorganisms 2021; 9:microorganisms9020305. [PMID: 33540689 PMCID: PMC7913009 DOI: 10.3390/microorganisms9020305] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/28/2021] [Accepted: 01/30/2021] [Indexed: 01/04/2023] Open
Abstract
Methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen commonly found in bone and joint infections, including septic arthritis. S. aureus virulence and the frailty of affected patients can cause several complications; a prompt and specific antibiotic treatment can positively affect the outcome of patients. We carried out an in-depth genomic characterization by Illumina whole genome sequencing and bioinformatics of two biofilm-producing M1 and M2 ST398 MSSA causing septic knee arthritis not-responding to antimicrobial therapy. The strains were characterized for antibiotic resistance, biofilm and adhesive properties as well as genomics, single nucleotide polymorphism phylogeny, resistomics and virulomics. Our results showed that M1 and M2 MSSA were ST398-t1451-agrI-Cap5, susceptible to cefoxitin and resistant to erythromycin and clindamycin, traits consistent with the lack of the SCCmec-locus and the presence of the sole blaZ and ermT. Furthermore, M1 and M2 were biofilm-producing and largely potentially adhesive strains, as indicated by the adhesion gene profile. Our data characterized a new human-adapted ST398 MSSA lineage, representing a "fusion" between the human-animal independent ST398 and the Livestock Associated (LA) ST398 lineages, forming biofilm and genomically predicted high adhesive, characterized by different genomic adaptation conferring a great ability to adhere to the host's extracellular matrix causing septic knee arthritis.
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Affiliation(s)
- Viviana Cafiso
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (F.L.V.); (A.Z.); (G.P.); (S.S.)
- Correspondence:
| | - Flavia Lo Verde
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (F.L.V.); (A.Z.); (G.P.); (S.S.)
| | - Alessandra Zega
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (F.L.V.); (A.Z.); (G.P.); (S.S.)
| | - Giuseppe Pigola
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (F.L.V.); (A.Z.); (G.P.); (S.S.)
| | - Roberto Rostagno
- Infectious Diseases Department of Sant’Andrea Hospital Vercelli, 13100 Vercelli, Italy; (R.R.); (S.B.)
| | - Silvio Borrè
- Infectious Diseases Department of Sant’Andrea Hospital Vercelli, 13100 Vercelli, Italy; (R.R.); (S.B.)
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy; (F.L.V.); (A.Z.); (G.P.); (S.S.)
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24
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Dettweiler M, Marquez L, Lin M, Sweeney-Jones AM, Chhetri BK, Zurawski DV, Kubanek J, Quave CL. Pentagalloyl glucose from Schinus terebinthifolia inhibits growth of carbapenem-resistant Acinetobacter baumannii. Sci Rep 2020; 10:15340. [PMID: 32948818 PMCID: PMC7501240 DOI: 10.1038/s41598-020-72331-w] [Citation(s) in RCA: 4] [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: 05/12/2020] [Accepted: 08/28/2020] [Indexed: 01/29/2023] Open
Abstract
The rise of antibiotic resistance has necessitated a search for new antimicrobials with potent activity against multidrug-resistant gram-negative pathogens, such as carbapenem-resistant Acinetobacter baumannii (CRAB). In this study, a library of botanical extracts generated from plants used to treat infections in traditional medicine was screened for growth inhibition of CRAB. A crude extract of Schinus terebinthifolia leaves exhibited 80% inhibition at 256 µg/mL and underwent bioassay-guided fractionation, leading to the isolation of pentagalloyl glucose (PGG), a bioactive gallotannin. PGG inhibited growth of both CRAB and susceptible A. baumannii (MIC 64-256 µg/mL), and also exhibited activity against Pseudomonas aeruginosa (MIC 16 µg/mL) and Staphylococcus aureus (MIC 64 µg/mL). A mammalian cytotoxicity assay with human keratinocytes (HaCaTs) yielded an IC50 for PGG of 256 µg/mL. Mechanistic experiments revealed iron chelation as a possible mode of action for PGG's activity against CRAB. Passaging assays for resistance did not produce any resistant mutants over a period of 21 days. In conclusion, PGG exhibits antimicrobial activity against CRAB, but due to known pharmacological restrictions in delivery, translation as a therapeutic may be limited to topical applications such as wound rinses and dressings.
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Affiliation(s)
- Micah Dettweiler
- Department of Dermatology, Emory University School of Medicine, Atlanta, GA, USA
| | - Lewis Marquez
- Molecular and Systems Pharmacology Program, Emory University, Atlanta, GA, USA
| | - Michelle Lin
- Center for the Study of Human Health, Emory University, Atlanta, GA, USA
| | - Anne M Sweeney-Jones
- School of Chemistry and Biochemistry, Center for Microbial Dynamics and Infection, Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Bhuwan Khatri Chhetri
- School of Chemistry and Biochemistry, Center for Microbial Dynamics and Infection, Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Daniel V Zurawski
- Wound Infections Department, Bacterial Diseases Branch, Center for Infectious Disease Research, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA
| | - Julia Kubanek
- School of Chemistry and Biochemistry, Center for Microbial Dynamics and Infection, Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Cassandra L Quave
- Department of Dermatology, Emory University School of Medicine, Atlanta, GA, USA.
- Center for the Study of Human Health, Emory University, Atlanta, GA, USA.
- Emory University Herbarium, Atlanta, GA, USA.
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25
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Vukotic G, Obradovic M, Novovic K, Di Luca M, Jovcic B, Fira D, Neve H, Kojic M, McAuliffe O. Characterization, Antibiofilm, and Depolymerizing Activity of Two Phages Active on Carbapenem-Resistant Acinetobacter baumannii. Front Med (Lausanne) 2020; 7:426. [PMID: 32974360 PMCID: PMC7461965 DOI: 10.3389/fmed.2020.00426] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 07/01/2020] [Indexed: 01/21/2023] Open
Abstract
Acinetobacter baumannii is a leading cause of healthcare-associated infections worldwide. Its various intrinsic and acquired mechanisms of antibiotic resistance make the therapeutic challenge even more serious. One of the promising alternative treatments that is increasingly highlighted is phage therapy, the therapeutic use of bacteriophages to treat bacterial infections. Two phages active against nosocomial carbapenem-resistant A. baumannii strain 6077/12, vB_AbaM_ISTD, and vB_AbaM_NOVI, were isolated from Belgrade wastewaters, purified, and concentrated using CsCl gradient ultracentrifugation. The phages were screened against 103 clinical isolates of A. baumannii from a laboratory collection and characterized based on plaque and virion morphology, host range, adsorption rate, and one-step growth curve. Given that phage ISTD showed a broader host range, better adsorption rate, shorter latent period, and larger burst size, its ability to lyse planktonic and biofilm-embedded cells was tested in detail. Phage ISTD yielded a 3.5- and 2-log reduction in planktonic and biofilm-associated viable bacterial cell count, respectively, but the effect was time-dependent. Both phages produced growing turbid halos around plaques indicating the synthesis of depolymerases, enzymes capable of degrading bacterial exopolysaccharides. Halos tested positive for presence of phages in the proximity of the plaque, but not further from the plaque, which indicates that the observed halo enlargement is a consequence of enzyme diffusion through the agar, independently of the phages. This notion was also supported by the growing halos induced by phage preparations applied on pregrown bacterial lawns, indicating that depolymerizing effect was achieved also on non-dividing sensitive cells. Overall, good rates of growth, fast adsorption rate, broad host range, and high depolymerizing activity, as well as antibacterial effectiveness against planktonic and biofilm-associated bacteria, make these phages good candidates for potential application in combating A. baumannii infections.
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Affiliation(s)
- Goran Vukotic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia.,Chair of Biochemistry and Molecular Biology, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Mina Obradovic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia
| | - Katarina Novovic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia
| | | | - Branko Jovcic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia.,Chair of Biochemistry and Molecular Biology, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Djordje Fira
- Chair of Biochemistry and Molecular Biology, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Horst Neve
- Department of Microbiology and Biotechnology, Max Rubner-Institut, Kiel, Germany
| | - Milan Kojic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia
| | - Olivia McAuliffe
- Department of Food Biosciences, Teagasc Food Research Centre, Fermoy, Ireland
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26
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Cafiso V, Stracquadanio S, Lo Verde F, De Guidi I, Zega A, Pigola G, Stefani S. Genomic and Long-Term Transcriptomic Imprints Related to the Daptomycin Mechanism of Action Occurring in Daptomycin- and Methicillin-Resistant Staphylococcus aureus Under Daptomycin Exposure. Front Microbiol 2020; 11:1893. [PMID: 32922373 PMCID: PMC7456847 DOI: 10.3389/fmicb.2020.01893] [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] [Received: 12/09/2019] [Accepted: 07/20/2020] [Indexed: 01/06/2023] Open
Abstract
Daptomycin (DAP) is one of the last-resort treatments for heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) and vancomycin-intermediate S. aureus (VISA) infections. DAP resistance (DAP-R) is multifactorial and mainly related to cell-envelope modifications caused by single-nucleotide polymorphisms and/or modulation mechanisms of transcription emerging as result of a self-defense process in response to DAP exposure. Nevertheless, the role of these adaptations remains unclear. We aim to investigate the comparative genomics and late post-exponential growth-phase transcriptomics of two DAP-resistant/DAP-susceptible (DAPR/S) methicillin-resistant S. aureus (MRSA) clinical strain pairs to focalize the genomic and long-term transcriptomic fingerprinting and adaptations related to the DAP mechanism of action acquired in vivo under DAP pressure using Illumina whole-genome sequencing (WGS), RNA-seq, bioinformatics, and real-time qPCR validation. Comparative genomics revealed that membrane protein and transcriptional regulator coding genes emerged as shared functional coding-gene clusters harboring mutational events related to the DAP-R onset in a strain-dependent manner. Pairwise transcriptomic enrichment analysis highlighted common and strain pair-dependent Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, whereas DAPR/S double-pair cross-filtering returned 53 differentially expressed genes (DEGs). A multifactorial long-term transcriptomic-network characterized DAPR MRSA includes alterations in (i) peptidoglycan biosynthesis, cell division, and cell-membrane (CM) organization genes, as well as a cidB/lytS autolysin genes; (ii) ldh2 involved in fermentative metabolism; (iii) CM-potential perturbation genes; and (iv) oxidative and heat/cold stress response-related genes. Moreover, a D-alanyl–D-alanine decrease in cell-wall muropeptide characterized DAP/glycopeptide cross-reduced susceptibility mechanisms in DAPR MRSA. Our data provide a snapshot of DAPR MRSA genomic and long-term transcriptome signatures related to the DAP mechanism of action (MOA) evidencing that a complex network of genomic changes and transcriptomic adaptations is required to acquire DAP-R.
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Affiliation(s)
- Viviana Cafiso
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Stefano Stracquadanio
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Flavia Lo Verde
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Irene De Guidi
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Alessandra Zega
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Giuseppe Pigola
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
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27
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Karakonstantis S. A systematic review of implications, mechanisms, and stability of in vivo emergent resistance to colistin and tigecycline in Acinetobacter baumannii. J Chemother 2020; 33:1-11. [PMID: 32677578 DOI: 10.1080/1120009x.2020.1794393] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The potential of A. baumannii for acquired resistance to last resort antibiotics (colistin and tigecycline) during treatment has important clinical implications, especially when dealing with patients failing to improve despite treatment with an active antimicrobial. However, the relevant literature remains scattered. Therefore, a systematic search was conducted in PubMed and Scopus. Several studies reported emergence of resistance to colistin or tigecycline during treatment, in most cases (86%) resulting in persistent or recurrent infections, especially in cases of emergent resistance without fitness cost. Lipopolysaccharide modification in the case of colistin and overexpression of efflux pumps in the case of tigecycline were the main mechanisms of resistance. Emergent colistin resistance is often associated with fitness cost which may result in re-emergence of the fitter and more virulent colistin susceptible strain after cessation of antibiotic pressure. Prospective studies are needed to determine the frequency of emergent resistance during treatment and its impact on patient outcomes.
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Affiliation(s)
- Stamatis Karakonstantis
- Internal Medicine Department, General Hospital of Heraklion Venizeleio, Heraklion, Crete, Greece.,School of medicine, University of Crete, Heraklion, Crete, Greece
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28
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Kathayat D, Antony L, Deblais L, Helmy YA, Scaria J, Rajashekara G. Small Molecule Adjuvants Potentiate Colistin Activity and Attenuate Resistance Development in Escherichia coli by Affecting pmrAB System. Infect Drug Resist 2020; 13:2205-2222. [PMID: 32764996 PMCID: PMC7360418 DOI: 10.2147/idr.s260766] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/16/2020] [Indexed: 12/22/2022] Open
Abstract
Background Colistin is one of the last-resort antibiotics to treat multi-drug resistant (MDR) Gram-negative bacterial infections in humans. Further, colistin has been also used to prevent and treat Enterobacteriaceae infections in food animals. However, chromosomal mutations and mobile colistin resistance (mcr) genes, which confer resistance to colistin, have been detected in bacterial isolates from food animals and humans worldwide; thus, limiting the use of colistin. Therefore, strategies that could aid in ameliorating colistin resistance are critically needed. Objective Investigate the adjuvant potential of novel small molecules (SMs) on colistin. Materials and Methods Previously, we identified 11 membrane-affecting SMs with bactericidal activity against avian pathogenic Escherichia coli (APEC). Here, we investigated the potentiation effect of those SMs on colistin using checkerboard assays and wax moth (Galleria mellonella) larval model. The impact of the SM combination on colistin resistance evolution was also investigated by analyzing whole genome sequences of APEC isolates passaged with colistin alone or in combination with SMs followed by quantitating pmrCAB and pmrH expression in those isolates. Results The SM combination synergistically reduced the minimum bactericidal concentration of colistin by at least 10-fold. In larvae, the SM combination increased the efficacy of colistin by two-fold with enhanced (>50%) survival and reduced (>4 logs) APEC load. Further, the SM combination decreased the frequency (5/6 to 1/6) of colistin resistance evolution and downregulated the pmrCAB and pmrH expression. Previously unknown mutations in pmrB (L14Q, T92P) and pmrA (A80V), which were predicted deleterious, were identified in the colistin-resistant (ColR) APEC isolates when passaged with colistin alone but not in combination with SMs. Our study also identified mutations in hypothetical and several phage-related proteins in ColR APEC isolates in concurrent with pmrAB mutations. Conclusion Our study identified two SMs (SM2 and SM3) that potentiated the colistin activity and attenuated the development of colistin resistance in APEC. These SMs can be developed as anti-evolution drugs that can slow down colistin resistance development.
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Affiliation(s)
- Dipak Kathayat
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH 44691, USA
| | - Linto Antony
- Animal Disease Research and Diagnostic Laboratory, Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD 57007, USA
| | - Loic Deblais
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH 44691, USA
| | - Yosra A Helmy
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH 44691, USA
| | - Joy Scaria
- Animal Disease Research and Diagnostic Laboratory, Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD 57007, USA
| | - Gireesh Rajashekara
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH 44691, USA
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29
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Karakonstantis S, Saridakis I. Colistin heteroresistance in Acinetobacter spp.: systematic review and meta-analysis of the prevalence and discussion of the mechanisms and potential therapeutic implications. Int J Antimicrob Agents 2020; 56:106065. [PMID: 32599229 DOI: 10.1016/j.ijantimicag.2020.106065] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 05/30/2020] [Accepted: 06/20/2020] [Indexed: 01/29/2023]
Abstract
BACKGROUND Colistin is one of the few remaining options for carbapenem-resistant Acinetobacter baumannii (A. baumannii); however, emergence of resistance from heteroresistant populations is possible. This review aimed to systematically search and consolidate the literature on the prevalence, mechanisms and therapeutic implications of colistin heteroresistance in Acinetobacter spp. METHODS A systematic search was conducted in PubMed and Scopus. The pooled prevalence of colistin heteroresistance was calculated using meta-analysis of proportions with the Freeman-Tukey transformation and the random-effects (DerSimonian and Laird) method. RESULTS Based on 15 studies the prevalence of colistin heteroresistance was 33% (95% CI 16-53%) but considerable heterogeneity was observed (I2 = 96%, P < 0.001). Prior exposure to colistin was associated with a higher proportion of resistant subpopulations. Colistin heteroresistance may result from chromosomal mutations in resistant subpopulations (predominantly in PmrAB and lpx genes) resulting in lipopolysaccharide modification or loss, or overexpression of efflux pumps. No dosage scheme of colistin monotherapy can prevent the emergence of resistant subpopulations in vitro, but few studies have reported in vivo emergence of resistance from heteroresistant A. baumannii during treatment, and studies examining the correlation between heteroresistance and clinical/microbiological outcomes are lacking. Several colistin-based combinations have been shown in vitro to prevent the emergence of the resistant subpopulations but none have been translated so far into clinical benefit. Reasons for this discrepancy are discussed. CONCLUSIONS Colistin heteroresistance was common but highly variable between studies. The impact of colistin heteroresistance (frequency of emergent resistance during treatment and correlation with treatment outcomes) requires further study.
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Affiliation(s)
- Stamatis Karakonstantis
- School of Medicine, University of Crete, Heraklion, Crete, Greece; Internal Medicine Department, General Hospital of Heraklion Venizeleio, Heraklion, Crete, Greece.
| | - Ioannis Saridakis
- Internal Medicine Department, General Hospital of Heraklion Venizeleio, Heraklion, Crete, Greece
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30
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Li M, Aye SM, Ahmed MU, Han ML, Li C, Song J, Boyce JD, Powell DR, Azad MAK, Velkov T, Zhu Y, Li J. Pan-transcriptomic analysis identified common differentially expressed genes of Acinetobacter baumannii in response to polymyxin treatments. Mol Omics 2020; 16:327-338. [PMID: 32469363 DOI: 10.1039/d0mo00015a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Multidrug-resistant Acinetobacter baumannii is a top-priority Gram-negative pathogen and polymyxins are a last-line therapeutic option. Previous systems pharmacological studies examining polymyxin killing and resistance usually focused on individual strains, and the derived knowledge could be limited by strain-specific genomic context. In this study, we examined the gene expression of five A. baumannii strains (34654, 1207552, 1428368, 1457504 and ATCC 19606) to determine the common differentially expressed genes in response to polymyxin treatments. A pan-genome containing 6061 genes was identified for 89 A. baumannii genomes from RefSeq database which included the five strains examined in this study; 2822 of the 6061 genes constituted the core genome. After 2 mg L-1 or 0.75 × MIC polymyxin treatments for 15 min, 41 genes were commonly up-regulated, including those involved in membrane biogenesis and homeostasis, lipoprotein and phospholipid trafficking, efflux pump and poly-N-acetylglucosamine biosynthesis; six genes were commonly down-regulated, three of which were related to fatty acid biosynthesis. Additionally, comparison of the gene expression at 15 and 60 min in ATCC 19606 revealed that polymyxin treatment resulted in a rapid change in amino acid metabolism at 15 min and perturbations on envelope biogenesis at both time points. This is the first pan-transcriptomic study for polymyxin-treated A. baumannii and our results identified that the remodelled outer membrane, up-regulated efflux pumps and down-regulated fatty acid biosynthesis might be essential for early responses to polymyxins in A. baumannii. Our findings provide important mechanistic insights into bacterial responses to polymyxin killing and may facilitate the optimisation of polymyxin therapy against this problematic 'superbug'.
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Affiliation(s)
- Mengyao Li
- Biomedicine Discovery Institute, Infection & Immunity Program and Department of Microbiology, Monash University, 19 Innovation Walk, Melbourne 3800, Australia.
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31
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Palmieri M, D’Andrea MM, Pelegrin AC, Perrot N, Mirande C, Blanc B, Legakis N, Goossens H, Rossolini GM, van Belkum A. Abundance of Colistin-Resistant, OXA-23- and ArmA-Producing Acinetobacter baumannii Belonging to International Clone 2 in Greece. Front Microbiol 2020; 11:668. [PMID: 32425900 PMCID: PMC7212473 DOI: 10.3389/fmicb.2020.00668] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/24/2020] [Indexed: 12/14/2022] Open
Abstract
Carbapenem resistant Acinetobacter baumannii (CRAB) represents one of the most challenging pathogens in clinical settings. Colistin is routinely used for treatment of infections by this pathogen, but increasing colistin resistance has been reported. We obtained 122 CRAB isolates from nine Greek hospitals between 2015 and 2017, and those colistin resistant (ColR; N = 40, 32.8%) were whole genome sequenced, also by including two colistin susceptible (ColS) isolates for comparison. All ColR isolates were characterized by a previously described mutation, PmrBA226V, which was associated with low-level colistin resistance. Some isolates were characterized by additional mutations in PmrB (E140V or L178F) or PmrA (K172I or D10N), first described here, and higher colistin minimum inhibitory concentrations (MICs), up to 64 mg/L. Mass spectrometry analysis of lipid A showed the presence of a phosphoethanolamine (pEtN) moiety on lipid A, likely resulting from the PmrA/B-induced pmrC overexpression. Interestingly, also the two ColS isolates had the same lipid A modification, suggesting that not all lipid A modifications lead to colistin resistance or that other factors could contribute to the resistance phenotype. Most of the isolates (N = 37, 92.5%) belonged to the globally distributed international clone (IC) 2 and comprised four different sequence types (STs) as defined by using the Oxford scheme (ST 425, 208, 451, and 436). Three isolates belonged to IC1 and ST1567. All the genomes harbored an intrinsic bla OXA-51 group carbapenemase gene, where bla OXA-66 and bla OXA-69 were associated with IC2 and IC1, respectively. Carbapenem resistance was due to the most commonly reported acquired carbapenemase gene bla OXA-23, with ISAba1 located upstream of the gene and likely increasing its expression. The armA gene, associated with high-level resistance to aminoglycosides, was detected in 87.5% of isolates. Collectively, these results revealed a convergent evolution of different clonal lineages toward the same colistin resistance mechanism, thus limiting the effective therapeutic options for the treatment of CRAB infections.
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Affiliation(s)
- Mattia Palmieri
- bioMérieux, Data Analytics Unit, La Balme-les-Grottes, France
| | - Marco Maria D’Andrea
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | | | - Nadine Perrot
- bioMérieux, R&D Microbiology, La Balme-les-Grottes, France
| | | | | | | | - Herman Goossens
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium
| | - Gian Maria Rossolini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
- Clinical Microbiology and Virology Unit, Florence Careggi University Hospital, Florence, Italy
| | - Alex van Belkum
- bioMérieux, Data Analytics Unit, La Balme-les-Grottes, France
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Cheng J, Kesavan DK, Vasudevan A, Cai W, Wang H, Su Z, Wang S, Xu H. Genome and Transcriptome Analysis of A. baumannii's "Transient" Increase in Drug Resistance under Tigecycline Pressure. J Glob Antimicrob Resist 2020; 22:219-225. [PMID: 32084603 DOI: 10.1016/j.jgar.2020.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/14/2020] [Accepted: 02/04/2020] [Indexed: 01/30/2023] Open
Abstract
OBJECTIVES As a common nosocomial infection bacterium, A. baumannii's drug resistance rate continues to rise. In this study, the objective was to explore the possible reasons for the increased drug resistance of A. baumannii after tigecycline treatment. METHODS Based on the drug resistance analysis of 183 clinical isolates of A. baumannii, a pair of strains (AB711 and AB721) which changed their resistance after treatment was selected. Tigecycline was used to induce the drug resistance of strain AB711 in vitro. The differential expressed genes from A. baumannii strains were analyzed using whole gene sequencing (WGS) and RNA sequencing (RNA-seq) combined with online MLST, SNP tools and bioinformatics software, and verified by reverse transcription quantitative polymerase chain reaction (RT-qPCR). RESULTS AB721 became more resistant to tetracyclines than AB711 at the initial detection. However, after a period of time, the resistance of AB711 and AB721 became consistent. This phenomenon can also be repeated using AB711 in vitro. After induction, the AB711 with increased MIC value of tigecycline was named AB712. The results of WGS, MLST and SNP based Phylogenetic tree indicated that AB711, AB712, AB721 were co-origin and belong to ST2 (Pasteur) / ST1791 (Oxford). Comparative transcriptome indicated that the Differential expression of some genes can play an important role in the resistance enhancement process of AB711. For example, compared with AB711, genes related to benzene-containing compound metabolic process, translation, ribosomal structure and biogenesis and so on were upregulated significantly in AB712. In addition, efflux pumps such as RND transporter permease subunit, EmrAB, MacB, and Tet resistance operon were also upregulated. CONCLUSION Tigcycline induced changes in the expression of some related genes in A. baumannii, which may be the main reason for its increased drug resistance.
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Affiliation(s)
- Jianjun Cheng
- International Genomics Research Center (IGRC), Jiangsu University, Zhenjiang, 212013, China; Department of Immunology, Jiangsu University, Zhenjiang, 212013, China
| | - Dinesh Kumar Kesavan
- International Genomics Research Center (IGRC), Jiangsu University, Zhenjiang, 212013, China
| | - Aparna Vasudevan
- International Genomics Research Center (IGRC), Jiangsu University, Zhenjiang, 212013, China
| | - Wei Cai
- International Genomics Research Center (IGRC), Jiangsu University, Zhenjiang, 212013, China
| | - Huixuan Wang
- International Genomics Research Center (IGRC), Jiangsu University, Zhenjiang, 212013, China
| | - Zhaoliang Su
- International Genomics Research Center (IGRC), Jiangsu University, Zhenjiang, 212013, China; Department of Immunology, Jiangsu University, Zhenjiang, 212013, China
| | - Shengjun Wang
- International Genomics Research Center (IGRC), Jiangsu University, Zhenjiang, 212013, China; Department of Laboratory Medicine, The Affiliated People's Hospital, Jiangsu University, Zhenjiang, 212001, China
| | - Huaxi Xu
- International Genomics Research Center (IGRC), Jiangsu University, Zhenjiang, 212013, China; Department of Immunology, Jiangsu University, Zhenjiang, 212013, China.
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Marano V, Marascio N, Pavia G, Lamberti AG, Quirino A, Musarella R, Casalinuovo F, Mazzitelli M, Trecarichi EM, Torti C, Matera G, Liberto MC. Identification of pmrB mutations as putative mechanism for colistin resistance in A. baumannii strains isolated after in vivo colistin exposure. Microb Pathog 2020; 142:104058. [PMID: 32058026 DOI: 10.1016/j.micpath.2020.104058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/20/2020] [Accepted: 02/10/2020] [Indexed: 12/13/2022]
Abstract
Colistin resistance among extensively-resistant Acinetobacter baumannii isolates is a serious health-care problem. Alterations in PmrA-PmrB two-component system have been associated with resistance to colistin. We investigated three pairs of colistin-susceptible and colistin-resistant A. baumannii, sequentially isolated from three patients before and after colistin treatment, respectively. The pmrA and pmrB genes were sequenced by Sanger method. Amino acidic positions and their effect on protein were predicted by InterPro and PROVEAN tools. Expression of pmrA, pmrB and pmrC genes was assessed by semi-quantitative reverse transcription-PCR (qRT-PCR). We found three different nonsynonymous substitutions P233T, E301G and L168K in pmrB coding region, each one in a different colistin resistance strain. The E301G and L168K substitutions represent novel mutations in pmrB, not previously described. Relative expression of pmrA, pmrB and pmrC mRNA increased in all colistin resistant strains. In our study, pmrB substitutions were associated with pmrC over-expression and colistin resistance. Further studies are necessary to understand their impact on modification of lipid A components.
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Affiliation(s)
- Vito Marano
- Department of Health Sciences, Unit of Clinical Microbiology, "Magna Graecia" University, 88100, Catanzaro, Italy
| | - Nadia Marascio
- Department of Health Sciences, Unit of Clinical Microbiology, "Magna Graecia" University, 88100, Catanzaro, Italy.
| | - Grazia Pavia
- Department of Health Sciences, Unit of Clinical Microbiology, "Magna Graecia" University, 88100, Catanzaro, Italy
| | - Angelo G Lamberti
- Department of Health Sciences, Unit of Clinical Microbiology, "Magna Graecia" University, 88100, Catanzaro, Italy
| | - Angela Quirino
- Department of Health Sciences, Unit of Clinical Microbiology, "Magna Graecia" University, 88100, Catanzaro, Italy
| | - Rosanna Musarella
- Institute for Experimental Veterinary Medicine of Southern Italy, 88100, Catanzaro, Italy
| | - Francesco Casalinuovo
- Institute for Experimental Veterinary Medicine of Southern Italy, 88100, Catanzaro, Italy
| | - Maria Mazzitelli
- Department of Medical and Surgical Sciences, Unit of Infectious and Tropical Diseases, "Magna Graecia" University, 88100, Catanzaro, Italy
| | - Enrico M Trecarichi
- Department of Medical and Surgical Sciences, Unit of Infectious and Tropical Diseases, "Magna Graecia" University, 88100, Catanzaro, Italy
| | - Carlo Torti
- Department of Medical and Surgical Sciences, Unit of Infectious and Tropical Diseases, "Magna Graecia" University, 88100, Catanzaro, Italy
| | - Giovanni Matera
- Department of Health Sciences, Unit of Clinical Microbiology, "Magna Graecia" University, 88100, Catanzaro, Italy
| | - Maria Carla Liberto
- Department of Health Sciences, Unit of Clinical Microbiology, "Magna Graecia" University, 88100, Catanzaro, Italy
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Cafiso V, Stracquadanio S, Lo Verde F, Dovere V, Zega A, Pigola G, Aranda J, Stefani S. COL R Acinetobacter baumannii sRNA Signatures: Computational Comparative Identification and Biological Targets. Front Microbiol 2020; 10:3075. [PMID: 32010115 PMCID: PMC6978653 DOI: 10.3389/fmicb.2019.03075] [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: 10/29/2019] [Accepted: 12/19/2019] [Indexed: 11/25/2022] Open
Abstract
Multidrug-Resistant (MDR) and Extensively Drug Resistant (XDR) Acinetobacter baumannii (Ab) represent a serious cause of healthcare-associated infections worldwide. Currently, the available treatment options are very restricted and colistin-based therapies are last-line treatments of these infections, even though colistin resistant (COLR) Ab have rarely been isolated yet. In bacteria, small non-coding RNAs (sRNAs) have been implicated in regulatory pathways of different biological functions, however, no knowledge exists about the sRNA role on the biological adaptation in COLRAb. Our study investigated two Italian XDR isogenic colistin-susceptible/resistant (COLS/R) Ab strain-pairs to discover new sRNA signatures. Comparative sRNA transcriptome (sRNAome) analyses were carried out by Illumina RNA-seq using both a Tru-Seq and a Short Insert library, whilst Ab ATCC 17978 and ACICU Reference Genome assembly, mapping, annotation and statistically significant differential expression (q-value ≤ 0.01) of the raw reads were performed by the Rockhopper tool. A computational filtering, sorting only similarly statistically significant differentially expressed (DE) sRNAs mapping on the same gene in both COLRAb isolates was conducted. COLR vs. COLS sRNAome, analyzed integrating the DE sRNAs obtained from the two different libraries, revealed some statistically significant DE sRNAs in COLRAb. In detail, we found: (i) two different under-expressed cis-acting sRNAs (AbsRNA1 and AbsRNA2) mapping in antisense orientation the 16S rRNA gene A1S_r01, (ii) one under-expressed cis-acting sRNA (AbsRNA3) targeting the A1S_2505 gene (hypothetical protein), (iii) one under-expressed microRNA-size small RNA fragment (AbsRNA4) and its pre-microAbsRNA4 targeting the A1S_0501 gene (hypothetical protein), (iv) as well as an over-expressed microRNA-size small RNA fragment (AbsRNA5) and its pre-microAbsRNA5 targeting the A1S_3097 gene (signal peptide). Custom TaqMan® probe-based real-time qPCRs validated the expression pattern of the selected sRNA candidates shown by RNA-seq. Furthermore, analysis on sRNA ΔA1S_r01, ΔA1S_2505 as well as the over-expressed A1S_3097 mutants revealed no effects on colistin resistance. Our study, for the first time, found the sRNAome signatures of clinical COLRAb with a computational prediction of their targets related to protein synthesis, host-microbe interaction and other different biological functions, including biofilm production, cell-cycle control, virulence, and antibiotic-resistance.
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Affiliation(s)
- Viviana Cafiso
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Stefano Stracquadanio
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Flavia Lo Verde
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Veronica Dovere
- Department of Translational Research and New Technology in Medicine and Surgery, Azienda Ospedaliero Universitaria Pisana, University of Pisa, Pisa, Italy
| | - Alessandra Zega
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Giuseppe Pigola
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Jesús Aranda
- Departament de Genètica i Microbiologia, Facultat de Biociènces, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
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Rafei R, Osman M, Dabboussi F, Hamze M. Update on the epidemiological typing methods for Acinetobacter baumannii. Future Microbiol 2019; 14:1065-1080. [DOI: 10.2217/fmb-2019-0134] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The outstanding ability of Acinetobacter baumannii to cause outbreaks and acquire multidrug resistance motivated the development of a plethora of typing techniques, which can help infection preventionists and hospital epidemiologists to more efficiently implement intervention controls. Nowadays, the world is witnessing a gradual transition from traditional typing methodology to whole genome sequencing-based approaches. Such approaches are opening new prospects and applications never achieved by existing typing methods. Herein, we provide the reader with an updated review on A. baumannii typing methods recapping the added value of well-established techniques previously applied for A. baumannii and detailing new ones (as clustered regularly interspaced short palindromic repeats-based typing) with a special focus on whole genome sequencing.
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Affiliation(s)
- Rayane Rafei
- Laboratoire Microbiologie Santé et Environnement (LMSE), Doctoral School of Science and Technology, Faculty of Public Health, Lebanese University, Tripoli, Lebanon
| | - Marwan Osman
- Laboratoire Microbiologie Santé et Environnement (LMSE), Doctoral School of Science and Technology, Faculty of Public Health, Lebanese University, Tripoli, Lebanon
| | - Fouad Dabboussi
- Laboratoire Microbiologie Santé et Environnement (LMSE), Doctoral School of Science and Technology, Faculty of Public Health, Lebanese University, Tripoli, Lebanon
| | - Monzer Hamze
- Laboratoire Microbiologie Santé et Environnement (LMSE), Doctoral School of Science and Technology, Faculty of Public Health, Lebanese University, Tripoli, Lebanon
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The Brief Case: A Fatal Case of Necrotizing Fasciitis Due to Multidrug-Resistant Acinetobacter baumannii. J Clin Microbiol 2019; 57:57/7/e01751-18. [PMID: 31239404 DOI: 10.1128/jcm.01751-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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