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Chuai X, Zhou Y, Feng J, Yu M, Wu Y, Han L, Zhao Y, Qiao H, Gao Z, Li J, Xie L, Zhao W, Wang C. Analysis of multidrug-resistant determinants of clinically isolated Acinetobacter baumannii CYZ via whole genome sequencing. Microbiol Immunol 2023; 67:396-403. [PMID: 37403254 DOI: 10.1111/1348-0421.13087] [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: 02/01/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 07/06/2023]
Abstract
Acinetobacter baumannii is a multidrug-resistant coccobacillus responsible for severe nosocomial infectious diseases. This study mainly focuses on investigating the antimicrobial resistance features of a clinically isolated strain (A. baumannii CYZ) using the PacBio Sequel II sequencing platform. The chromosomal size of A. baumannii CYZ is 3,960,760 bp, which contains a total of 3803 genes with a G + C content of 39.06%. Functional analysis performed using the Clusters of Orthologous Groups of Proteins (COGs), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, as well as the Comprehensive Antibiotic Resistance Database (CARD) revealed a complicated set of antimicrobial resistance determinants in the genome of A. baumannii CYZ, which were mainly classified into multidrug efflux pumps and transport systems, β-lactamase relative and penicillin-binding proteins, aminoglycoside modification enzymes, alternation of antibiotic target sites, lipopolysaccharide relative, and other mechanisms. A total of 35 antibiotics were tested for the antimicrobial susceptibility of A. baumannii CYZ, and the organism exhibited a stronger antimicrobial resistance ability. The phylogenetic relationship indicated that A. baumannii CYZ has high homology with A. baumannii ATCC 17978; however, the former also exhibited its specific genome characteristics. Our research results give insight into the genetic antimicrobial-resistant features of A. baumannii CYZ as well as provide a genetic basis for the further study of the phenotype.
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Affiliation(s)
- Xia Chuai
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
| | - Yaya Zhou
- School of Basic Medical Sciences, Hebei Medical University, Shijiazhuang, PR China
| | - Junhua Feng
- Clinical Laboratory, The Fourth Hospital, Hebei Medical University, Shijiazhuang, PR China
| | - Menghan Yu
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
| | - Yan Wu
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
| | - Lujuan Han
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
| | - Yan Zhao
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
| | - Hongxiu Qiao
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
- Department of Experimental Center of Teaching, Hebei Medical University, Shijiazhuang, PR China
| | - Zhiyun Gao
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
| | - Jian Li
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
| | - Lixin Xie
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
| | - Wenting Zhao
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
| | - Changle Wang
- Department of Pathogenic Biology, Hebei Medical University, Shijiazhuang, PR China
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Colquhoun JM, Farokhyfar M, Anderson AC, Bethel CR, Bonomo RA, Clarke AJ, Rather PN. Collateral Changes in Cell Physiology Associated with ADC-7 β-Lactamase Expression in Acinetobacter baumannii. Microbiol Spectr 2023; 11:e0464622. [PMID: 37074187 PMCID: PMC10269689 DOI: 10.1128/spectrum.04646-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 03/15/2023] [Indexed: 04/20/2023] Open
Abstract
The ADC (AmpC) β-lactamase is universally present in the Acinetobacter baumannii chromosome, suggesting it may have a yet-to-be-identified cellular function. Using peptidoglycan composition analysis, we show that overexpressing the ADC-7 β-lactamase in A. baumannii drives changes consistent with altered l,d-transpeptidase activity. Based on this, we tested whether cells overexpressing ADC-7 would exhibit new vulnerabilities. As proof of principle, a screen of transposon insertions revealed that an insertion in the distal 3' end of canB, encoding carbonic anhydrase, resulted in a significant loss of viability when the adc-7 gene was overexpressed. A canB deletion mutant exhibited a more pronounced loss of viability than the transposon insertion, and this became amplified when cells overexpressed ADC-7. Interestingly, overexpression of the OXA-23 or TEM-1 β-lactamases also led to a pronounced loss of viability in cells with reduced carbonic anhydrase activity. In addition, we demonstrate that reduced CanB activity led to increased sensitivity to peptidoglycan synthesis inhibitors and to the carbonic anhydrase inhibitor ethoxzolamide. Furthermore, this strain exhibited a synergistic interaction with the peptidoglycan inhibitor fosfomycin and ethoxzolamide. Our results highlight the impact of ADC-7 overexpression on cell physiology and reveal that the essential carbonic anhydrase CanB may represent a novel target for antimicrobial agents that would exhibit increased potency against β-lactamase-overexpressing A. baumannii. IMPORTANCE Acinetobacter baumannii has become resistant to all classes of antibiotics, with β-lactam resistance responsible for the majority of treatment failures. New classes of antimicrobials are needed to treat this high-priority pathogen. This study had uncovered a new genetic vulnerability in β-lactamase-expressing A. baumannii, where reduced carbonic anhydrase activity becomes lethal. Inhibitors of carbonic anhydrase could represent a new method for treating A. baumannii infections.
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Affiliation(s)
- Jennifer M. Colquhoun
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, Georgia, USA
| | | | - Alexander C. Anderson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Christopher R. Bethel
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs, Cleveland, Ohio, USA
| | - Robert A. Bonomo
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs, Cleveland, Ohio, USA
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, Ohio, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Case Western Reserve University, Cleveland, Ohio, USA
| | - Anthony J. Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
- Department of Chemistry & Biochemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Philip N. Rather
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, Georgia, USA
- Research Service, Atlanta VA Medical Center, Decatur, Georgia, USA
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Sharma S, Kaushik V, Kulshrestha M, Tiwari V. Different Efflux Pump Systems in Acinetobacter baumannii and Their Role in Multidrug Resistance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023. [DOI: 10.1007/5584_2023_771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen that usually causes difficult-to-treat infections due to its low intrinsic antibiotic susceptibility and outstanding capacity for becoming resistant to antibiotics. In addition, it has a remarkable metabolic versatility, being able to grow in different habitats, from natural niches to different and changing inpatient environments. Study of the environmental conditions that shape genetic and phenotypic changes of P. aeruginosa toward antibiotic resistance supposes a novelty, since experimental evolution assays are usually performed with well-defined antibiotics in regular laboratory growth media. Therefore, in this work we address the extent to which the nutrients’ availability may constrain the evolution of antibiotic resistance. We determined that P. aeruginosa genetic trajectories toward resistance to tobramycin, ceftazidime, and ceftazidime-avibactam are different when evolving in laboratory rich medium, urine, or synthetic sputum. Furthermore, our study, linking genotype with phenotype, showed a clear impact of each analyzed environment on both the fitness and resistance level associated with particular resistance mutations. This indicates that the phenotype associated with specific resistance mutations is variable and dependent on the bacterial metabolic state in each particular habitat. Our results support that the design of evolution-based strategies to tackle P. aeruginosa infections should be based on robust patterns of evolution identified within each particular infection and body location. IMPORTANCE Predicting evolution toward antibiotic resistance (AR) and its associated trade-offs, such as collateral sensitivity, is important to design evolution-based strategies to tackle AR. However, the effect of nutrients' availability on such evolution, particularly those that can be found under in vivo infection conditions, has been barely addressed. We analyzed the evolutionary patterns of P. aeruginosa in the presence of antibiotics in different media, including urine and synthetic sputum, whose compositions are similar to the ones in infections, finding that AR evolution differs, depending on growth conditions. Furthermore, the representative mutants isolated under each condition tested render different AR levels and fitness costs, depending on nutrients’ availability, supporting the idea that environmental constraints shape the phenotypes associated with specific AR mutations. Consequently, the selection of AR mutations that render similar phenotypes is environment dependent. The analysis of evolution patterns toward AR requires studying growth conditions mimicking those that bacteria face during in vivo evolution.
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Evasion of Antimicrobial Activity in Acinetobacter baumannii by Target Site Modifications: An Effective Resistance Mechanism. Int J Mol Sci 2022; 23:ijms23126582. [PMID: 35743027 PMCID: PMC9223528 DOI: 10.3390/ijms23126582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 06/05/2022] [Accepted: 06/10/2022] [Indexed: 11/17/2022] Open
Abstract
Acinetobacter baumannii is a Gram-negative bacillus that causes multiple infections that can become severe, mainly in hospitalized patients. Its high ability to persist on abiotic surfaces and to resist stressors, together with its high genomic plasticity, make it a remarkable pathogen. Currently, the isolation of strains with high antimicrobial resistance profiles has gained relevance, which complicates patient treatment and prognosis. This resistance capacity is generated by various mechanisms, including the modification of the target site where antimicrobial action is directed. This mechanism is mainly generated by genetic mutations and contributes to resistance against a wide variety of antimicrobials, such as β-lactams, macrolides, fluoroquinolones, aminoglycosides, among others, including polymyxin resistance, which includes colistin, a rescue antimicrobial used in the treatment of multidrug-resistant strains of A. baumannii and other Gram-negative bacteria. Therefore, the aim of this review is to provide a detailed and up-to-date description of antimicrobial resistance mediated by the target site modification in A. baumannii, as well as to detail the therapeutic options available to fight infections caused by this bacterium.
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Abstract
Small molecule adjuvants that enhance the activity of established antibiotics represent promising agents in the battle against antibiotic resistance. Adjuvants generally act by inhibiting antibiotic resistance processes, and specifying the process acted on is a critical step in defining an adjuvant's mechanism of action. This step is typically carried out biochemically by identifying molecules that bind adjuvants and then inferring their roles in resistance. Here, we present a complementary genetic strategy based on identifying mutations that both sensitize cells to antibiotic and make them "adjuvant blind." We tested the approach in Acinetobacter baumannii AB5075 using two adjuvants: a well-characterized β-lactamase inhibitor (avibactam) and a compound enhancing outer membrane permeability (aryl 2-aminoimidazole AI-1). The avibactam studies showed that the adjuvant potentiated one β-lactam (ceftazidime) through action on a single β-lactamase (GES-14) and a second (meropenem) by targeting two different enzymes (GES-14 and OXA-23). Mutations impairing disulfide bond formation (DsbAB) also reduced potentiation, possibly by impairing β-lactamase folding. Mutations reducing AI-1 potentiation of canonical Gram-positive antibiotics (vancomycin and clarithromycin) blocked lipooligosaccharide (LOS/LPS) synthesis or its acyl modification. The results indicate that LOS-mediated outer membrane impermeability is targeted by the adjuvant and show the importance of acylation in the resistance. As part of the study, we employed Acinetobacter baylyi as a model to verify the generality of the A. baumannii results and identified the principal resistance genes for ceftazidime, meropenem, vancomycin, and clarithromycin in A. baumannii AB5075. Overall, the work provides a foundation for analyzing adjuvant action using a comprehensive genetic approach. IMPORTANCE One strategy to confront the antibiotic resistance crisis is through the development of adjuvant compounds that increase the efficacy of established drugs. A key step in the development of a natural product adjuvant as a drug is identifying the resistance process it undermines to enhance antibiotic activity. Previous procedures designed to accomplish this have relied on biochemical identification of cell components that bind adjuvant. Here, we present a complementary strategy based on identifying mutations that eliminate adjuvant activity.
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OXA-23 β-Lactamase Overexpression in Acinetobacter baumannii Drives Physiological Changes Resulting in New Genetic Vulnerabilities. mBio 2021; 12:e0313721. [PMID: 34872351 PMCID: PMC8649759 DOI: 10.1128/mbio.03137-21] [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] [Indexed: 11/20/2022] Open
Abstract
β-Lactamase expression is the major mechanism of resistance to penicillins, cephalosporins, and carbapenems in the multidrug-resistant (MDR) bacterium Acinetobacter baumannii. In fact, stable high-level expression of at least one β-lactamase has been rapidly increasing and reported to occur in up to 98.5% of modern A. baumannii isolates recovered in the clinic. Moreover, the OXA-51 β-lactamase is universally present in the A. baumannii chromosome, suggesting it may have a cellular function beyond antibiotic resistance. However, the consequences associated with OXA β-lactamase overexpression on A. baumannii physiology are not well understood. Using peptidoglycan composition analysis, we show that overexpressing the OXA-23 β-lactamase in A. baumannii drives significant collateral changes with alterations consistent with increased amidase activity. Consequently, we predicted that these changes create new cellular vulnerabilities. As proof of principle, a small screen of random transposon insertions revealed three genes, where mutations resulted in a greater than 19-fold loss of viability when OXA-23 was overexpressed. The identified genes remained conditionally essential even when a catalytically inactive OXA-23 β-lactamase was overexpressed. In addition, we demonstrated a synergistic lethal relationship between OXA-23 overexpression and a CRISPR interference (CRISPRi) knockdown of the essential peptidoglycan synthesis enzyme MurA. Last, OXA-23 overexpression sensitized cells to two inhibitors of peptidoglycan synthesis, d-cycloserine and fosfomycin. Our results highlight the impact of OXA-23 hyperexpression on peptidoglycan integrity and reveal new genetic vulnerabilities, which may represent novel targets for antimicrobial agents specific to MDR A. baumannii and other OXA β-lactamase-overexpressing Enterobacteriaceae, while having no impact on the normal flora. IMPORTANCE Acinetobacter baumannii has become a serious pathogen in both hospital and community settings. The β-lactam class of antibiotics is a primary treatment option for A. baumannii infections, and expression of β-lactamases is the most frequent mechanism of resistance in this bacterium. New approaches to treating multidrug-resistant A. baumannii strains are needed. In this study, we demonstrate that overexpressing the OXA-23 β-lactamase leads to significant collateral changes, where peptidoglycan structure is altered. We have identified genes that become selectively essential in OXA-23-expressing strains and confirmed the relationship between altered peptidoglycan and OXA-23 expression by demonstrating that OXA-23 overexpression sensitizes cells to genetic and chemical inhibition of peptidoglycan synthesis. This work paves the way for the identification of new antimicrobial targets, where inhibitors would selectively kill β-lactamase-expressing strains.
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8
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A New Class of Cell Wall-Recycling l,d-Carboxypeptidase Determines β-Lactam Susceptibility and Morphogenesis in Acinetobacter baumannii. mBio 2021; 12:e0278621. [PMID: 34872350 PMCID: PMC8649774 DOI: 10.1128/mbio.02786-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The hospital-acquired pathogen Acinetobacter baumannii possesses a complex cell envelope that is key to its multidrug resistance and virulence. The bacterium, however, lacks many canonical enzymes that build the envelope in model organisms. Instead, A. baumannii contains a number of poorly annotated proteins that may allow alternative mechanisms of envelope biogenesis. We demonstrated previously that one of these unusual proteins, ElsL, is required for maintaining a characteristic short rod shape and for withstanding antibiotics that attack the septal cell wall. Curiously, ElsL is composed of a leaderless YkuD-family domain usually found in secreted, cell wall-modifying l,d-transpeptidases (LDTs). Here, we show that, rather than being an LDT, ElsL is actually a new class of cytoplasmic l,d-carboxypeptidase (LDC) that provides a critical step in cell wall recycling previously thought to be missing from A. baumannii. Absence of ElsL impairs cell wall integrity, morphology, and intrinsic resistance due to buildup of murein tetrapeptide precursors, toxicity of which is bypassed by preventing muropeptide recycling. Multiple pathways in the cell become sites of vulnerability when ElsL is inactivated, including l,d-cross-link formation, cell division, and outer membrane lipid homoeostasis, reflecting its pleiotropic influence on envelope physiology. We thus reveal a novel class of cell wall-recycling LDC critical to growth and homeostasis of A. baumannii and likely many other bacteria.
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Hübner I, Shapiro JA, Hoßmann J, Drechsel J, Hacker SM, Rather PN, Pieper DH, Wuest WM, Sieber SA. Broad Spectrum Antibiotic Xanthocillin X Effectively Kills Acinetobacter baumannii via Dysregulation of Heme Biosynthesis. ACS CENTRAL SCIENCE 2021; 7:488-498. [PMID: 33791430 PMCID: PMC8006170 DOI: 10.1021/acscentsci.0c01621] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Indexed: 05/19/2023]
Abstract
Isonitrile natural products exhibit promising antibacterial activities. However, their mechanism of action (MoA) remains largely unknown. Based on the nanomolar potency of xanthocillin X (Xan) against diverse difficult-to-treat Gram-negative bacteria, including the critical priority pathogen Acinetobacter baumannii, we performed in-depth studies to decipher its MoA. While neither metal binding nor cellular protein targets were detected as relevant for Xan's antibiotic effects, sequencing of resistant strains revealed a conserved mutation in the heme biosynthesis enzyme porphobilinogen synthase (PbgS). This mutation caused impaired enzymatic efficiency indicative of reduced heme production. This discovery led to the validation of an untapped mechanism, by which direct heme sequestration of Xan prevents its binding into cognate enzyme pockets resulting in uncontrolled cofactor biosynthesis, accumulation of porphyrins, and corresponding stress with deleterious effects for bacterial viability. Thus, Xan represents a promising antibiotic displaying activity even against multidrug resistant strains, while exhibiting low toxicity to human cells.
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Affiliation(s)
- Ines Hübner
- Center
for Functional Protein Assemblies at the Department of Chemistry and
Chair of Organic Chemistry II, Technische
Universität München, Garching D-85748, Germany
| | - Justin A. Shapiro
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Jörn Hoßmann
- Microbial
Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Jonas Drechsel
- Center
for Functional Protein Assemblies at the Department of Chemistry and
Chair of Organic Chemistry II, Technische
Universität München, Garching D-85748, Germany
| | - Stephan M. Hacker
- Department
of Chemistry, Technische Universität
München, Garching D-85748, Germany
| | - Philip N. Rather
- Emory Antibiotic Resistance Center and Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, United States
- Research
Service, Atlanta VA Medical Center, Decatur, Georgia 30033, United States
| | - Dietmar H. Pieper
- Microbial
Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - William M. Wuest
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
- Emory Antibiotic Resistance Center and Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - Stephan A. Sieber
- Center
for Functional Protein Assemblies at the Department of Chemistry and
Chair of Organic Chemistry II, Technische
Universität München, Garching D-85748, Germany
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10
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Wang P, Li RQ, Wang L, Yang WT, Zou QH, Xiao D. Proteomic Analyses of Acinetobacter baumannii Clinical Isolates to Identify Drug Resistant Mechanism. Front Cell Infect Microbiol 2021; 11:625430. [PMID: 33718272 PMCID: PMC7943614 DOI: 10.3389/fcimb.2021.625430] [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: 11/03/2020] [Accepted: 01/11/2021] [Indexed: 12/25/2022] Open
Abstract
Acinetobacter baumannii is one of the main causes of nosocomial infections. Increasing numbers of multidrug-resistant Acinetobacter baumannii cases have been reported in recent years, but its antibiotic resistance mechanism remains unclear. We studied 9 multidrug-resistant (MDR) and 10 drug-susceptible Acinetobacter baumannii clinical isolates using Label free, TMT labeling approach and glycoproteomics analysis to identify proteins related to drug resistance. Our results showed that 164 proteins exhibited different expressions between MDR and drug-susceptible isolates. These differential proteins can be classified into six groups: a. proteins related to antibiotic resistance, b. membrane proteins, membrane transporters and proteins related to membrane formation, c. Stress response-related proteins, d. proteins related to gene expression and protein translation, e. metabolism-related proteins, f. proteins with unknown function or other functions containing biofilm formation and virulence. In addition, we verified seven proteins at the transcription level in eight clinical isolates by using quantitative RT-PCR. Results showed that four of the selected proteins have positive correlations with the protein level. This study provided an insight into the mechanism of antibiotic resistance of multidrug-resistant Acinetobacter baumannii.
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Affiliation(s)
- Ping Wang
- Department of Microbiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Ren-Qing Li
- Institute for Control of Infectious Diseases and Endemic Diseases, Beijing Center for Disease Prevention and Control, Beijing, China
| | - Lei Wang
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Wen-Tao Yang
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Qing-Hua Zou
- Department of Microbiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Di Xiao
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
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11
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Verma P, Tiwari M, Tiwari V. Efflux pumps in multidrug-resistant Acinetobacter baumannii: Current status and challenges in the discovery of efflux pumps inhibitors. Microb Pathog 2021; 152:104766. [PMID: 33545327 DOI: 10.1016/j.micpath.2021.104766] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 01/13/2021] [Accepted: 01/22/2021] [Indexed: 12/14/2022]
Abstract
Acinetobacter baumannii is an ESKAPE pathogen known to cause fatal nosocomial infections. With the surge of multidrug resistance (MDR) in the bacterial system, effective treatment measures have become very limited. The MDR in A. baumannii is contributed by various factors out of which efflux pumps have gained major attention due to their broad substrate specificity and wide distribution among bacterial species. The efflux pumps are involved in the MDR as well as contribute to other physiological processes in bacteria, therefore, it is critically important to inhibit efflux pumps in order to combat emerging resistance. The present review provides insight about the different efflux pump systems in A. baumannii and their role in multidrug resistance. A major focus has been put on the different strategies and alternate therapeutics to inhibit the efflux system. This includes use of different efflux pump inhibitors-natural, synthetic or combinatorial therapy. The use of phage therapy and nanoparticles for inhibiting efflux pumps have also been discussed here. Moreover, the present review provides the knowledge of barriers in development of efflux pump inhibitors (EPIs) and their approval for commercialization. Here, different prospectives have been discussed to improve the therapeutic development process and make it more compatible for clinical use.
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Affiliation(s)
- Privita Verma
- Department of Biochemistry, Central University of Rajasthan, Bandarsindri, Ajmer, 305817, India
| | - Monalisa Tiwari
- Department of Biochemistry, Central University of Rajasthan, Bandarsindri, Ajmer, 305817, India
| | - Vishvanath Tiwari
- Department of Biochemistry, Central University of Rajasthan, Bandarsindri, Ajmer, 305817, India.
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12
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Geisinger E, Mortman NJ, Dai Y, Cokol M, Syal S, Farinha A, Fisher DG, Tang AY, Lazinski DW, Wood S, Anthony J, van Opijnen T, Isberg RR. Antibiotic susceptibility signatures identify potential antimicrobial targets in the Acinetobacter baumannii cell envelope. Nat Commun 2020; 11:4522. [PMID: 32908144 PMCID: PMC7481262 DOI: 10.1038/s41467-020-18301-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 08/13/2020] [Indexed: 11/13/2022] Open
Abstract
A unique, protective cell envelope contributes to the broad drug resistance of the nosocomial pathogen Acinetobacter baumannii. Here we use transposon insertion sequencing to identify A. baumannii mutants displaying altered susceptibility to a panel of diverse antibiotics. By examining mutants with antibiotic susceptibility profiles that parallel mutations in characterized genes, we infer the function of multiple uncharacterized envelope proteins, some of which have roles in cell division or cell elongation. Remarkably, mutations affecting a predicted cell wall hydrolase lead to alterations in lipooligosaccharide synthesis. In addition, the analysis of altered susceptibility signatures and antibiotic-induced morphology patterns allows us to predict drug synergies; for example, certain beta-lactams appear to work cooperatively due to their preferential targeting of specific cell wall assembly machineries. Our results indicate that the pathogen may be effectively inhibited by the combined targeting of multiple pathways critical for envelope growth.
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Affiliation(s)
- Edward Geisinger
- Department of Biology, Northeastern University, Boston, MA, 02115, USA.
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
| | - Nadav J Mortman
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Yunfei Dai
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Murat Cokol
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Sapna Syal
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Andrew Farinha
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Delaney G Fisher
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Amy Y Tang
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - David W Lazinski
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Stephen Wood
- Biology Department, Boston College, Chestnut Hill, MA, 02467, USA
| | - Jon Anthony
- Biology Department, Boston College, Chestnut Hill, MA, 02467, USA
| | - Tim van Opijnen
- Biology Department, Boston College, Chestnut Hill, MA, 02467, USA
| | - Ralph R Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
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13
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Characterization of RelA in Acinetobacter baumannii. J Bacteriol 2020; 202:JB.00045-20. [PMID: 32229531 DOI: 10.1128/jb.00045-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/26/2020] [Indexed: 12/21/2022] Open
Abstract
In response to nutrient depletion, the RelA and SpoT proteins generate the signaling molecule (p)ppGpp, which then controls a number of downstream effectors to modulate cell physiology. In Acinetobacter baumannii strain AB5075, a relA ortholog (ABUW_3302) was identified by a transposon insertion that conferred an unusual colony phenotype. An in-frame deletion in relA (ΔrelA) failed to produce detectable levels of ppGpp when amino acid starvation was induced with serine hydroxamate. The ΔrelA mutant was blocked from switching from the virulent opaque colony variant (VIR-O) to the avirulent translucent colony variant (AV-T), but the rate of AV-T to VIR-O switching was unchanged. In addition, the ΔrelA mutation resulted in a pronounced hypermotile phenotype on 0.35% agar plates. This hypermotility was dependent on the activation of a LysR regulator ABUW_1132, which was required for expression of AbaR, a LuxR family quorum-sensing regulator. In the ΔrelA mutant, ABUW_1132 was also required for the increased expression of an operon composed of the ABUW_3766-ABUW_3773 genes required for production of the surfactant-like lipopeptide acinetin 505. Additional phenotypes identified in the ΔrelA mutant included (i) cell elongation at high density, (ii) reduced formation of persister cells tolerant to colistin and rifampin, and (iii) decreased virulence in a Galleria mellonella model.IMPORTANCE Acinetobacter baumannii is a pathogen of worldwide importance. Due to the increasing prevalence of antibiotic resistance, these infections are becoming increasingly difficult to treat. New therapies are required to combat multidrug-resistant isolates. The role of RelA in A. baumannii is largely unknown. This study demonstrates that like in other bacteria, RelA controls a variety of functions, including virulence. Strategies to inhibit the activity of RelA and the resulting production of ppGpp could inhibit virulence and may represent a new therapeutic approach.
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Essential gene deletions producing gigantic bacteria. PLoS Genet 2019; 15:e1008195. [PMID: 31181062 PMCID: PMC6586353 DOI: 10.1371/journal.pgen.1008195] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/20/2019] [Accepted: 05/14/2019] [Indexed: 01/01/2023] Open
Abstract
To characterize the consequences of eliminating essential functions needed for peptidoglycan synthesis, we generated deletion mutations of Acinetobacter baylyi by natural transformation and visualized the resulting microcolonies of dead cells. We found that loss of genes required for peptidoglycan precursor synthesis or polymerization led to the formation of polymorphic giant cells with diameters that could exceed ten times normal. Treatment with antibiotics targeting early or late steps of peptidoglycan synthesis also produced giant cells. The giant cells eventually lysed, although they were partially stabilized by osmotic protection. Genome-scale transposon mutant screening (Tn-seq) identified mutations that blocked or accelerated giant cell formation. Among the mutations that blocked the process were those inactivating a function predicted to cleave murein glycan chains (the MltD murein lytic transglycosylase), suggesting that giant cell formation requires MltD hydrolysis of existing peptidoglycan. Among the mutations that accelerated giant cell formation after ß-lactam treatment were those inactivating an enzyme that produces unusual 3->3 peptide cross-links in peptidoglycan (the LdtG L,D-transpeptidase). The mutations may weaken the sacculus and make it more vulnerable to further disruption. Although the study focused on A. baylyi, we found that a pathogenic relative (A. baumannii) also produced giant cells with genetic dependencies overlapping those of A. baylyi. Overall, the analysis defines a genetic pathway for giant cell formation conserved in Acinetobacter species in which independent initiating branches converge to create the unusual cells. Although essential genes control the most basic functions of bacterial life, they are difficult to study genetically because mutants lacking the functions die. We have developed a simple procedure for creating bacteria in which different essential genes have been completely deleted, making it possible to analyze the roles of the missing functions based on the features of the dead cells that result. When genes needed for the production of the cell wall were inactivated, the bacteria formed bizarre giant cells. It was possible to identify the functions responsible for forming the giant cells, and to formulate a model for how they form. Since cell wall synthesis is one of the most important antibiotic targets, understanding how bacteria respond to its disruption may ultimately help in developing procedures to overcome antibiotic resistant bacterial infections.
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Papp-Wallace KM, Nguyen NQ, Jacobs MR, Bethel CR, Barnes MD, Kumar V, Bajaksouzian S, Rudin SD, Rather PN, Bhavsar S, Ravikumar T, Deshpande PK, Patil V, Yeole R, Bhagwat SS, Patel MV, van den Akker F, Bonomo RA. Strategic Approaches to Overcome Resistance against Gram-Negative Pathogens Using β-Lactamase Inhibitors and β-Lactam Enhancers: Activity of Three Novel Diazabicyclooctanes WCK 5153, Zidebactam (WCK 5107), and WCK 4234. J Med Chem 2018; 61:4067-4086. [PMID: 29627985 DOI: 10.1021/acs.jmedchem.8b00091] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Limited treatment options exist to combat infections caused by multidrug-resistant (MDR) Gram-negative bacteria possessing broad-spectrum β-lactamases. The design of novel β-lactamase inhibitors is of paramount importance. Here, three novel diazabicyclooctanes (DBOs), WCK 5153, zidebactam (WCK 5107), and WCK 4234 (compounds 1-3, respectively), were synthesized and biochemically characterized against clinically important bacteria. Compound 3 inhibited class A, C, and D β-lactamases with unprecedented k2/ K values against OXA carbapenemases. Compounds 1 and 2 acylated class A and C β-lactamses rapidly but not the tested OXAs. Compounds 1-3 formed highly stable acyl-complexes as demonstrated by mass spectrometry. Crystallography revealed that 1-3 complexed with KPC-2 adopted a "chair conformation" with the sulfate occupying the carboxylate binding region. The cefepime-2 and meropenem-3 combinations were effective in murine peritonitis and neutropenic lung infection models caused by MDR Acinetobacter baumannii. Compounds 1-3 are novel β-lactamase inhibitors that demonstate potent cross-class inhibition, and clinical studies targeting MDR infections are warranted.
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Affiliation(s)
- Krisztina M Papp-Wallace
- Research Service , Louis Stokes Cleveland Department of Veterans Affairs Medical Center , 10701 East Boulevard , Cleveland , Ohio 44106 , United States
| | | | - Michael R Jacobs
- Department of Pathology , University Hospitals, Cleveland Medical Center , Cleveland , Ohio 44106 , United States
| | - Christopher R Bethel
- Research Service , Louis Stokes Cleveland Department of Veterans Affairs Medical Center , 10701 East Boulevard , Cleveland , Ohio 44106 , United States
| | - Melissa D Barnes
- Research Service , Louis Stokes Cleveland Department of Veterans Affairs Medical Center , 10701 East Boulevard , Cleveland , Ohio 44106 , United States
| | | | - Saralee Bajaksouzian
- Department of Pathology , University Hospitals, Cleveland Medical Center , Cleveland , Ohio 44106 , United States
| | - Susan D Rudin
- Research Service , Louis Stokes Cleveland Department of Veterans Affairs Medical Center , 10701 East Boulevard , Cleveland , Ohio 44106 , United States
| | - Philip N Rather
- Department of Microbiology and Immunology , Emory University School of Medicine Atlanta , Georgia 30322 , United States.,Research Service , Atlanta VA Medical Center , Decatur , Georgia 30033 , United States
| | | | | | | | - Vijay Patil
- Wockhardt Research Centre , Aurangabad , India
| | | | | | | | | | - Robert A Bonomo
- Research Service , Louis Stokes Cleveland Department of Veterans Affairs Medical Center , 10701 East Boulevard , Cleveland , Ohio 44106 , United States
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Clinical and Pathophysiological Overview of Acinetobacter Infections: a Century of Challenges. Clin Microbiol Rev 2017; 30:409-447. [PMID: 27974412 DOI: 10.1128/cmr.00058-16] [Citation(s) in RCA: 626] [Impact Index Per Article: 89.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Acinetobacter is a complex genus, and historically, there has been confusion about the existence of multiple species. The species commonly cause nosocomial infections, predominantly aspiration pneumonia and catheter-associated bacteremia, but can also cause soft tissue and urinary tract infections. Community-acquired infections by Acinetobacter spp. are increasingly reported. Transmission of Acinetobacter and subsequent disease is facilitated by the organism's environmental tenacity, resistance to desiccation, and evasion of host immunity. The virulence properties demonstrated by Acinetobacter spp. primarily stem from evasion of rapid clearance by the innate immune system, effectively enabling high bacterial density that triggers lipopolysaccharide (LPS)-Toll-like receptor 4 (TLR4)-mediated sepsis. Capsular polysaccharide is a critical virulence factor that enables immune evasion, while LPS triggers septic shock. However, the primary driver of clinical outcome is antibiotic resistance. Administration of initially effective therapy is key to improving survival, reducing 30-day mortality threefold. Regrettably, due to the high frequency of this organism having an extreme drug resistance (XDR) phenotype, early initiation of effective therapy is a major clinical challenge. Given its high rate of antibiotic resistance and abysmal outcomes (up to 70% mortality rate from infections caused by XDR strains in some case series), new preventative and therapeutic options for Acinetobacter spp. are desperately needed.
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Lee CR, Lee JH, Park M, Park KS, Bae IK, Kim YB, Cha CJ, Jeong BC, Lee SH. Biology of Acinetobacter baumannii: Pathogenesis, Antibiotic Resistance Mechanisms, and Prospective Treatment Options. Front Cell Infect Microbiol 2017; 7:55. [PMID: 28348979 PMCID: PMC5346588 DOI: 10.3389/fcimb.2017.00055] [Citation(s) in RCA: 496] [Impact Index Per Article: 70.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 02/13/2017] [Indexed: 12/27/2022] Open
Abstract
Acinetobacter baumannii is undoubtedly one of the most successful pathogens responsible for hospital-acquired nosocomial infections in the modern healthcare system. Due to the prevalence of infections and outbreaks caused by multi-drug resistant A. baumannii, few antibiotics are effective for treating infections caused by this pathogen. To overcome this problem, knowledge of the pathogenesis and antibiotic resistance mechanisms of A. baumannii is important. In this review, we summarize current studies on the virulence factors that contribute to A. baumannii pathogenesis, including porins, capsular polysaccharides, lipopolysaccharides, phospholipases, outer membrane vesicles, metal acquisition systems, and protein secretion systems. Mechanisms of antibiotic resistance of this organism, including acquirement of β-lactamases, up-regulation of multidrug efflux pumps, modification of aminoglycosides, permeability defects, and alteration of target sites, are also discussed. Lastly, novel prospective treatment options for infections caused by multi-drug resistant A. baumannii are summarized.
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Affiliation(s)
- Chang-Ro Lee
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University Yongin, South Korea
| | - Jung Hun Lee
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University Yongin, South Korea
| | - Moonhee Park
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji UniversityYongin, South Korea; DNA Analysis Division, Seoul Institute, National Forensic ServiceSeoul, South Korea
| | - Kwang Seung Park
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University Yongin, South Korea
| | - Il Kwon Bae
- Department of Dental Hygiene, College of Health and Welfare, Silla University Busan, South Korea
| | - Young Bae Kim
- Biotechnology Program, North Shore Community College Danvers, MA, USA
| | - Chang-Jun Cha
- Department of Systems Biotechnology, College of Biotechnology and Natural Resources, Chung-Ang University Anseong, South Korea
| | - Byeong Chul Jeong
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University Yongin, South Korea
| | - Sang Hee Lee
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University Yongin, South Korea
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