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George NL, Bennett EC, Orlando BJ. Guarding the walls: the multifaceted roles of Bce modules in cell envelope stress sensing and antimicrobial resistance. J Bacteriol 2024; 206:e0012324. [PMID: 38869304 PMCID: PMC11270860 DOI: 10.1128/jb.00123-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024] Open
Abstract
Bacteria have developed diverse strategies for defending their cell envelopes from external threats. In Firmicutes, one widespread strategy is to use Bce modules-membrane protein complexes that unite a peptide-detoxifying ABC transporter with a stress response coordinating two-component system. These modules provide specific, front-line defense for a wide variety of antimicrobial peptides and small molecule antibiotics as well as coordinate responses for heat, acid, and oxidative stress. Because of these abilities, Bce modules play important roles in virulence and the development of antibiotic resistance in a variety of pathogens, including Staphylococcus, Streptococcus, and Enterococcus species. Despite their importance, Bce modules are still poorly understood, with scattered functional data in only a small number of species. In this review, we will discuss Bce module structure in light of recent cryo-electron microscopy structures of the B. subtilis BceABRS module and explore the common threads and variations-on-a-theme in Bce module mechanisms across species. We also highlight the many remaining questions about Bce module function. Understanding these multifunctional membrane complexes will enhance our understanding of bacterial stress sensing and may point toward new therapeutic targets for highly resistant pathogens.
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Affiliation(s)
- Natasha L. George
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
- Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, Michigan, USA
| | - Ellen C. Bennett
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
- Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, Michigan, USA
| | - Benjamin J. Orlando
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
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2
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Ali L, Abdel Aziz MH. Crosstalk involving two-component systems in Staphylococcus aureus signaling networks. J Bacteriol 2024; 206:e0041823. [PMID: 38456702 PMCID: PMC11025333 DOI: 10.1128/jb.00418-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2024] Open
Abstract
Staphylococcus aureus poses a serious global threat to human health due to its pathogenic nature, adaptation to environmental stress, high virulence, and the prevalence of antimicrobial resistance. The signaling network in S. aureus coordinates and integrates various internal and external inputs and stimuli to adapt and formulate a response to the environment. Two-component systems (TCSs) of S. aureus play a central role in this network where surface-expressed histidine kinases (HKs) receive and relay external signals to their cognate response regulators (RRs). Despite the purported high fidelity of signaling, crosstalk within TCSs, between HK and non-cognate RR, and between TCSs and other systems has been detected widely in bacteria. The examples of crosstalk in S. aureus are very limited, and there needs to be more understanding of its molecular recognition mechanisms, although some crosstalk can be inferred from similar bacterial systems that share structural similarities. Understanding the cellular processes mediated by this crosstalk and how it alters signaling, especially under stress conditions, may help decipher the emergence of antibiotic resistance. This review highlights examples of signaling crosstalk in bacteria in general and S. aureus in particular, as well as the effect of TCS mutations on signaling and crosstalk.
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Affiliation(s)
- Liaqat Ali
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
| | - May H. Abdel Aziz
- Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, Texas, USA
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Crozier D, Gray JM, Maltas JA, Bonomo RA, Burke ZDC, Card KJ, Scott JG. The evolution of diverse antimicrobial responses in vancomycin-intermediate Staphylococcus aureus and its therapeutic implications. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.30.569373. [PMID: 38077036 PMCID: PMC10705500 DOI: 10.1101/2023.11.30.569373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2023]
Abstract
Staphylococcus aureus causes endocarditis, osteomyelitis, and bacteremia. Clinicians often prescribe vancomycin as an empiric therapy to account for methicillin-resistant S. aureus (MRSA) and narrow treatment based on culture susceptibility results. However, these results reflect a single time point before empiric treatment and represent a limited subset of the total bacterial population within the patient. Thus, while they may indicate that the infection is susceptible to a particular drug, this recommendation may no longer be accurate during therapy. Here, we addressed how antibiotic susceptibility changes over time by accounting for evolution. We evolved 18 methicillin-susceptible S. aureus (MSSA) populations under increasing vancomycin concentrations until they reached intermediate resistance levels. Sequencing revealed parallel mutations that affect cell membrane stress response and cell-wall biosynthesis. The populations exhibited repeated cross-resistance to daptomycin and varied responses to meropenem, gentamicin, and nafcillin. We accounted for this variability by deriving likelihood estimates that express a population's probability of exhibiting a drug response following vancomycin treatment. Our results suggest antistaphylococcal penicillins are preferable first-line treatments for MSSA infections but also highlight the inherent uncertainty that evolution poses to effective therapies. Infections may take varied evolutionary paths; therefore, considering evolution as a probabilistic process should inform our therapeutic choices.
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Ganesan N, Mishra B, Felix L, Mylonakis E. Antimicrobial Peptides and Small Molecules Targeting the Cell Membrane of Staphylococcus aureus. Microbiol Mol Biol Rev 2023; 87:e0003722. [PMID: 37129495 PMCID: PMC10304793 DOI: 10.1128/mmbr.00037-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023] Open
Abstract
Clinical management of Staphylococcus aureus infections presents a challenge due to the high incidence, considerable virulence, and emergence of drug resistance mechanisms. The treatment of drug-resistant strains, such as methicillin-resistant S. aureus (MRSA), is further complicated by the development of tolerance and persistence to antimicrobial agents in clinical use. To address these challenges, membrane disruptors, that are not generally considered during drug discovery for agents against S. aureus, should be explored. The cell membrane protects S. aureus from external stresses and antimicrobial agents, but membrane-targeting antimicrobial agents are probably less likely to promote bacterial resistance. Nontypical linear cationic antimicrobial peptides (AMPs), highly modified AMPs such as daptomycin (lipopeptide), bacitracin (cyclic peptide), and gramicidin S (cyclic peptide), are currently in clinical use. Recent studies have demonstrated that AMPs and small molecules can penetrate the cell membrane of S. aureus, inhibit phospholipid biosynthesis, or block the passage of solutes between the periplasm and the exterior of the cell. In addition to their primary mechanism of action (MOA) that targets the bacterial membrane, AMPs and small molecules may also impact bacteria through secondary mechanisms such as targeting the biofilm, and downregulating virulence genes of S. aureus. In this review, we discuss the current state of research into cell membrane-targeting AMPs and small molecules and their potential mechanisms of action against drug-resistant physiological forms of S. aureus, including persister cells and biofilms.
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Affiliation(s)
- Narchonai Ganesan
- Infectious Diseases Division, Alpert Medical School, Brown University, Providence, Rhode Island, USA
| | - Biswajit Mishra
- Infectious Diseases Division, Alpert Medical School, Brown University, Providence, Rhode Island, USA
- Department of Medicine, The Miriam Hospital, Providence, Rhode Island, USA
| | - LewisOscar Felix
- Infectious Diseases Division, Alpert Medical School, Brown University, Providence, Rhode Island, USA
| | - Eleftherios Mylonakis
- Infectious Diseases Division, Alpert Medical School, Brown University, Providence, Rhode Island, USA
- Department of Medicine, Houston Methodist Hospital, Houston, Texas, USA
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5
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Pouget C, Chatre C, Lavigne JP, Pantel A, Reynes J, Dunyach-Remy C. Effect of Antibiotic Exposure on Staphylococcus epidermidis Responsible for Catheter-Related Bacteremia. Int J Mol Sci 2023; 24:ijms24021547. [PMID: 36675063 PMCID: PMC9863639 DOI: 10.3390/ijms24021547] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 12/16/2022] [Accepted: 01/09/2023] [Indexed: 01/15/2023] Open
Abstract
Coagulase-negative staphylococci (CoNS) and especially Staphylococcus epidermidis are responsible for health care infections, notably in the presence of foreign material (e.g., venous or central-line catheters). Catheter-related bacteremia (CRB) increases health care costs and mortality. The aim of our study was to evaluate the impact of 15 days of antibiotic exposure (ceftobiprole, daptomycin, linezolid and vancomycin) at sub-inhibitory concentration on the resistance, fitness and genome evolution of 36 clinical strains of S. epidermidis responsible for CRB. Resistance was evaluated by antibiogram, the ability to adapt metabolism by the Biofilm Ring test® and the in vivo nematode virulence model. The impact of antibiotic exposure was determined by whole-genome sequencing (WGS) and biofilm formation experiments. We observed that S. epidermidis strains presented a wide variety of virulence potential and biofilm formation. After antibiotic exposure, S. epidermidis strains adapted their fitness with an increase in biofilm formation. Antibiotic exposure also affected genes involved in resistance and was responsible for cross-resistance between vancomycin, daptomycin and ceftobiprole. Our data confirmed that antibiotic exposure modified bacterial pathogenicity and the emergence of resistant bacteria.
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Affiliation(s)
- Cassandra Pouget
- Department of Microbiology and Hospital Hygiene, Bacterial Virulence and Chronic Infections, INSERM U1047, CHU Nîmes Univiversity Montpellier, CEDEX 09, 30029 Nîmes, France
| | - Clotilde Chatre
- Department of Infectious and Tropical Diseases, CH Perpignan, 66000 Perpignan, France
| | - Jean-Philippe Lavigne
- Department of Microbiology and Hospital Hygiene, Bacterial Virulence and Chronic Infections, INSERM U1047, CHU Nîmes Univiversity Montpellier, CEDEX 09, 30029 Nîmes, France
| | - Alix Pantel
- Department of Microbiology and Hospital Hygiene, Bacterial Virulence and Chronic Infections, INSERM U1047, CHU Nîmes Univiversity Montpellier, CEDEX 09, 30029 Nîmes, France
| | - Jacques Reynes
- Department of Infectious and Tropical Diseases, IRD UMI 233, INSERM U1175, CHU Montpellier, University Montpellier, CEDEX 5, 34295 Montpellier, France
| | - Catherine Dunyach-Remy
- Department of Microbiology and Hospital Hygiene, Bacterial Virulence and Chronic Infections, INSERM U1047, CHU Nîmes Univiversity Montpellier, CEDEX 09, 30029 Nîmes, France
- Correspondence: ; Tel.: +33-4-6668-3202
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6
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Zhu X, Hong A, Sun X, Wang W, He G, Luo H, Wu Z, Xu Q, Hu Z, Wu X, Huang D, Li L, Zhao X, Deng X. Nigericin is effective against multidrug resistant gram-positive bacteria, persisters, and biofilms. Front Cell Infect Microbiol 2022; 12:1055929. [PMID: 36605124 PMCID: PMC9807916 DOI: 10.3389/fcimb.2022.1055929] [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: 09/28/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Multidrug-resistant (MDR) bacteria pose a significant clinical threat to human health, but the development of antibiotics cannot meet the urgent need for effective agents, especially those that can kill persisters and biofilms. Here, we reported that nigericin showed potent bactericidal activity against various clinical MDR Gram-positive bacteria, persisters and biofilms, with low frequencies of resistance development. Moreover, nigericin exhibited favorable in vivo efficacy in deep-seated mouse biofilm, murine skin and bloodstream infection models. With Staphylococcus aureus, nigericin disrupted ATP production and electron transport chain; cell death was associated with altered membrane structure and permeability. Obtaining nigericin-resistant/tolerant mutants required multiple rounds of challenge, and, cross-resistance to members of several antimicrobial classes was absent, probably due to distinct nigericin action with the GraSR two-component regulatory system. Thus, our work reveals that nigericin is a promising antibiotic candidate for the treatment of chronic or recurrent infections caused by Gram-positive bacteria.
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Affiliation(s)
- Xiaoli Zhu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China,State-province Joint Engineering Laboratory of Targeted Drugs from Natural Products, Xiamen University, Xiamen, Fujian, China
| | - Anjin Hong
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China,State-province Joint Engineering Laboratory of Targeted Drugs from Natural Products, Xiamen University, Xiamen, Fujian, China
| | - Xihuan Sun
- Clinical Microbiology Laboratory, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian, China
| | - Weijie Wang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, Fujian, China
| | - Guanghui He
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China,State-province Joint Engineering Laboratory of Targeted Drugs from Natural Products, Xiamen University, Xiamen, Fujian, China
| | - Huan Luo
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, Fujian, China
| | - Zhenhua Wu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China,State-province Joint Engineering Laboratory of Targeted Drugs from Natural Products, Xiamen University, Xiamen, Fujian, China
| | - Qingyan Xu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China,State-province Joint Engineering Laboratory of Targeted Drugs from Natural Products, Xiamen University, Xiamen, Fujian, China
| | - Zhiyu Hu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China,State-province Joint Engineering Laboratory of Targeted Drugs from Natural Products, Xiamen University, Xiamen, Fujian, China
| | - Xiaobing Wu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China,State-province Joint Engineering Laboratory of Targeted Drugs from Natural Products, Xiamen University, Xiamen, Fujian, China
| | - Donghong Huang
- Clinical Microbiology Laboratory, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian, China,*Correspondence: Donghong Huang, ; Li Li, ; Xilin Zhao, ; Xianming Deng,
| | - Li Li
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China,State-province Joint Engineering Laboratory of Targeted Drugs from Natural Products, Xiamen University, Xiamen, Fujian, China,*Correspondence: Donghong Huang, ; Li Li, ; Xilin Zhao, ; Xianming Deng,
| | - Xilin Zhao
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, Fujian, China,*Correspondence: Donghong Huang, ; Li Li, ; Xilin Zhao, ; Xianming Deng,
| | - Xianming Deng
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China,State-province Joint Engineering Laboratory of Targeted Drugs from Natural Products, Xiamen University, Xiamen, Fujian, China,*Correspondence: Donghong Huang, ; Li Li, ; Xilin Zhao, ; Xianming Deng,
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7
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Thomas P, Deming MA, Sarkar A. β-Lactamase Suppression as a Strategy to Target Methicillin-Resistant Staphylococcus aureus: Proof of Concept. ACS OMEGA 2022; 7:46213-46221. [PMID: 36570253 PMCID: PMC9773349 DOI: 10.1021/acsomega.2c04381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 11/21/2022] [Indexed: 06/17/2023]
Abstract
β-Lactamase (penicillinase) renders early, natural β-lactams like penicillin G useless against methicillin-resistant Staphylococcus aureus (MRSA), which also expresses PBP2a, responsible for resistance to semisynthetic, penicillinase-insensitive β-lactams like oxacillin. Antimicrobial discovery is difficult, and resistance exists against most treatment options. Enhancing β-lactams against MRSA would revive its clinical utility. Most research on antimicrobial enhancement against MRSA focuses on oxacillin due to β-lactamase expression. Yet, Moreillon and others have demonstrated that penicillin G is as potent against a β-lactamase gene knockout strain, as vancomycin is against wild-type MRSA. Penicillin G overcame PBP2a because β-lactamase activity was blocked. Additionally, animals treated with a combination of direct β-lactamase inhibitors like sulbactam and clavulanate with penicillin G developed resistant infections, clearly demonstrating that direct inhibition of β-lactamase is not a good strategy. Here, we show that 50 μM pyrimidine-2-amines (P2As) reduce the minimum inhibitory concentration (MIC) of penicillin G against MRSA strains by up to 16-fold by reducing β-lactamase activity but not by direct inhibition of the enzyme. Oxacillin was not enhanced due to PBP2a expression, demonstrating the advantage of penicillin G over penicillinase-insensitive β-lactams. P2As modulate an unknown global regulator but not established antimicrobial-enhancement targets Stk1 and VraS. P2As are a practical implementation of Moreillon's principle of suppressing β-lactamase activity to make penicillin G useful against MRSA, without employing direct enzyme inhibitors.
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8
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Molecular Mechanisms of Drug Resistance in Staphylococcus aureus. Int J Mol Sci 2022; 23:ijms23158088. [PMID: 35897667 PMCID: PMC9332259 DOI: 10.3390/ijms23158088] [Citation(s) in RCA: 80] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/18/2022] [Accepted: 07/20/2022] [Indexed: 12/03/2022] Open
Abstract
This paper discusses the mechanisms of S. aureus drug resistance including: (1) introduction. (2) resistance to beta-lactam antibiotics, with particular emphasis on the mec genes found in the Staphylococcaceae family, the structure and occurrence of SCCmec cassettes, as well as differences in the presence of some virulence genes and its expression in major epidemiological types and clones of HA-MRSA, CA-MRSA, and LA-MRSA strains. Other mechanisms of resistance to beta-lactam antibiotics will also be discussed, such as mutations in the gdpP gene, BORSA or MODSA phenotypes, as well as resistance to ceftobiprole and ceftaroline. (3) Resistance to glycopeptides (VRSA, VISA, hVISA strains, vancomycin tolerance). (4) Resistance to oxazolidinones (mutational and enzymatic resistance to linezolid). (5) Resistance to MLS-B (macrolides, lincosamides, ketolides, and streptogramin B). (6) Aminoglycosides and spectinomicin, including resistance genes, their regulation and localization (plasmids, transposons, class I integrons, SCCmec), and types and spectrum of enzymes that inactivate aminoglycosides. (7). Fluoroquinolones (8) Tetracyclines, including the mechanisms of active protection of the drug target site and active efflux of the drug from the bacterial cell. (9) Mupirocin. (10) Fusidic acid. (11) Daptomycin. (12) Resistance to other antibiotics and chemioterapeutics (e.g., streptogramins A, quinupristin/dalfopristin, chloramphenicol, rifampicin, fosfomycin, trimethoprim) (13) Molecular epidemiology of MRSA.
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9
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Hort M, Bertsche U, Nozinovic S, Dietrich A, Schrötter AS, Mildenberger L, Axtmann K, Berscheid A, Bierbaum G. The Role of β-Glycosylated Wall Teichoic Acids in the Reduction of Vancomycin Susceptibility in Vancomycin-Intermediate Staphylococcus aureus. Microbiol Spectr 2021; 9:e0052821. [PMID: 34668723 PMCID: PMC8528128 DOI: 10.1128/spectrum.00528-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 09/12/2021] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is an opportunistic pathogen that causes a wide range of infections. Due to the rapid evolution of antibiotic resistance that leads to treatment failure, it is important to understand the underlying mechanisms. Here, the cell wall structures of several laboratory vancomycin-intermediate S. aureus (VISA) strains were analyzed. Among the VISA strains were S. aureus VC40, which accumulated 79 mutations, including most importantly 2 exchanges in the histidine-kinase VraS, and developed full resistance against vancomycin (MIC, 64 μg/ml); a revertant S. aureus VC40R, which has an additional mutation in vraR (MIC, 4 μg/ml); and S. aureus VraS(VC40), in which the 2 vraS mutations were reconstituted into a susceptible background (MIC, 4 μg/ml). A ultraperformance liquid chromatography (UPLC) analysis showed that S. aureus VC40 had a significantly decreased cross-linking of the peptidoglycan. Both S. aureus VC40 and S. aureus VraS(VC40) displayed reduced autolysis and an altered autolysin profile in a zymogram. Most striking was the significant increase in d-alanine and N-acetyl-d-glucosamine (GlcNAc) substitution of the wall teichoic acids (WTAs) in S. aureus VC40. Nuclear magnetic resonance (NMR) analysis revealed that this strain had mostly β-glycosylated WTAs in contrast to the other strains, which showed only the α-glycosylation peak. Salt stress induced the incorporation of β-GlcNAc anomers and drastically increased the vancomycin MIC for S. aureus VC40R. In addition, β-glycosylated WTAs decreased the binding affinity of AtlA, the major autolysin of S. aureus, to the cell wall, compared with α-glycosylated WTAs. In conclusion, there is a novel connection between wall teichoic acids, autolysis, and vancomycin susceptibility in S. aureus. IMPORTANCE Infections with methicillin-resistant Staphylococcus aureus are commonly treated with vancomycin. This antibiotic inhibits cell wall biosynthesis by binding to the cell wall building block lipid II. We set out to characterize the mechanisms leading to decreased vancomycin susceptibility in a laboratory-generated strain, S. aureus VC40. This strain has an altered cell wall architecture with a thick cell wall with low cross-linking, which provides decoy binding sites for vancomycin. The low cross-linking, necessary for this resistance mechanism, decreases the stability of the cell wall against lytic enzymes, which separate the daughter cells. Protection against these enzymes is provided by another cell wall polymer, the teichoic acids, which contain an unusually high substitution with sugars in the β-conformation. By experimentally increasing the proportion of β-N-acetyl-d-glucosamine in a closely related isolate through the induction of salt stress, we could show that the β-conformation of the sugars plays a vital role in the resistance of S. aureus VC40.
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Affiliation(s)
- Michael Hort
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Ute Bertsche
- Department of Infection Biology, University of Tuebingen, Tuebingen, Germany
| | | | - Alina Dietrich
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Anne Sophie Schrötter
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Laura Mildenberger
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Katharina Axtmann
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Anne Berscheid
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Gabriele Bierbaum
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
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10
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Su M, Davis MH, Peterson J, Solis-Lemus C, Satola SW, Read TD. Effect of genetic background on the evolution of Vancomycin-Intermediate Staphylococcus aureus (VISA). PeerJ 2021; 9:e11764. [PMID: 34306830 PMCID: PMC8284308 DOI: 10.7717/peerj.11764] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 06/22/2021] [Indexed: 11/20/2022] Open
Abstract
Vancomycin-intermediate Staphylococcus aureus (VISA) typically arises through accumulation of chromosomal mutations that alter cell-wall thickness and global regulatory pathways. Genome-based prediction of VISA requires understanding whether strain background influences patterns of mutation that lead to resistance. We used an iterative method to experimentally evolve three important methicillin-resistant S. aureus (MRSA) strain backgrounds-(CC1, CC5 and CC8 (USA300)) to generate a library of 120 laboratory selected VISA isolates. At the endpoint, isolates had vancomycin MICs ranging from 4 to 10 μg/mL. We detected mutations in more than 150 genes, but only six genes (already known to be associated with VISA from prior studies) were mutated in all three background strains (walK, prs, rpoB, rpoC, vraS, yvqF). We found evidence of interactions between loci (e.g., vraS and yvqF mutants were significantly negatively correlated) and rpoB, rpoC, vraS and yvqF were more frequently mutated in one of the backgrounds. Increasing vancomycin resistance was correlated with lower maximal growth rates (a proxy for fitness) regardless of background. However, CC5 VISA isolates had higher MICs with fewer rounds of selection and had lower fitness costs than the CC8 VISA isolates. Using multivariable regression, we found that genes differed in their contribution to overall MIC depending on the background. Overall, these results demonstrated that VISA evolved through mutations in a similar set of loci in all backgrounds, but the effect of mutation in common genes differed with regard to fitness and contribution to resistance in different strains.
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Affiliation(s)
- Michelle Su
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Michelle H Davis
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Jessica Peterson
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Claudia Solis-Lemus
- Wisconsin Institute for Discovery and Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sarah W Satola
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Timothy D Read
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia, USA.,Department of Dermatology, School of Medicine, Emory University, Atlanta, Georgia, USA
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11
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Wang W, Sun B. VraCP regulates cell wall metabolism and antibiotic resistance in vancomycin-intermediate Staphylococcus aureus strain Mu50. J Antimicrob Chemother 2021; 76:1712-1723. [PMID: 33948657 PMCID: PMC8212773 DOI: 10.1093/jac/dkab113] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 03/13/2021] [Indexed: 01/29/2023] Open
Abstract
Objectives Vancomycin-intermediate Staphylococcus aureus (VISA) is increasingly being reported. Previous studies have shown that vraC and vraP may be involved in vancomycin resistance, although the molecular mechanism remains elusive. Methods The vraC (SAV0577), vraP (SAV0578) and vraCP mutants were constructed in Mu50 by allelic replacement. Some common VISA phenotypes were assessed in mutants, such as, susceptibility to the cell wall-associated antibiotics, cell wall thickness, autolysis activity and growth rate. RT-qPCR was performed to reveal the differential genes associated with these phenotypes. The binding abilities of VraC and VraCP to the promoters of target genes were determined by electrophoretic mobility shift assay (EMSA). Results VraP forms a stable complex with VraC to preserve their own stability. The vraC, vraP and vraCP mutants exhibited increased susceptibility to the cell wall-associated antibiotics and thinner cell walls compared with the WT strain. Consistent with these phenotypes, RT-qPCR revealed downregulated transcription of glyS, sgtB, ddl and alr2, which are involved in cell wall biosynthesis. Moreover, the transcription of cell wall hydrolysis genes, including sceD, lytM and isaA, was significantly downregulated, supporting the finding that mutants exhibited reduced autolysis rates. EMSA confirmed that both VraC and VraCP can directly bind to the sceD, lytM and isaA promoter regions containing the consensus sequence (5′-TTGTAAN2AN3TGTAA-3′), which is crucial for the binding of VraCP with target genes. GFP-reporter assays further revealed VraC and VraCP can enhance promoter activity of sceD to positively regulate its expression. Conclusions vraCP plays a significant role in cell wall metabolism and antibiotic resistance in Mu50.
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Affiliation(s)
- Wanying Wang
- Department of Oncology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, People's Republic of China
| | - Baolin Sun
- Department of Oncology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, People's Republic of China
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12
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Curating and comparing 114 strain-specific genome-scale metabolic models of Staphylococcus aureus. NPJ Syst Biol Appl 2021; 7:30. [PMID: 34188046 PMCID: PMC8241996 DOI: 10.1038/s41540-021-00188-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 05/25/2021] [Indexed: 12/19/2022] Open
Abstract
Staphylococcus aureus is a high-priority pathogen causing severe infections with high morbidity and mortality worldwide. Many S. aureus strains are methicillin-resistant (MRSA) or even multi-drug resistant. It is one of the most successful and prominent modern pathogens. An effective fight against S. aureus infections requires novel targets for antimicrobial and antistaphylococcal therapies. Recent advances in whole-genome sequencing and high-throughput techniques facilitate the generation of genome-scale metabolic models (GEMs). Among the multiple applications of GEMs is drug-targeting in pathogens. Hence, comprehensive and predictive metabolic reconstructions of S. aureus could facilitate the identification of novel targets for antimicrobial therapies. This review aims at giving an overview of all available GEMs of multiple S. aureus strains. We downloaded all 114 available GEMs of S. aureus for further analysis. The scope of each model was evaluated, including the number of reactions, metabolites, and genes. Furthermore, all models were quality-controlled using MEMOTE, an open-source application with standardized metabolic tests. Growth capabilities and model similarities were examined. This review should lead as a guide for choosing the appropriate GEM for a given research question. With the information about the availability, the format, and the strengths and potentials of each model, one can either choose an existing model or combine several models to create models with even higher predictive values. This facilitates model-driven discoveries of novel antimicrobial targets to fight multi-drug resistant S. aureus strains.
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13
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Zhu J, Liu B, Shu X, Sun B. A novel mutation of walK confers vancomycin-intermediate resistance in methicillin-susceptible Staphylococcus aureus. Int J Med Microbiol 2021; 311:151473. [PMID: 33445057 DOI: 10.1016/j.ijmm.2021.151473] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 12/24/2020] [Accepted: 01/04/2021] [Indexed: 10/22/2022] Open
Abstract
With the treatment failure by vancomycin and poor clinical outcomes, the emergence and spread of vancomycin intermediate-resistant Staphylococcus aureus (VISA) has raised more concerns in recent years. While most VISA strains are isolated from methicillin-resistant S. aureus (MRSA), the mechanism underlying the generation of VISA from methicillin-susceptible S. aureus (MSSA) is still largely unknown. Here, we identified a total of 10 mutations in 9 genes through comparative genome analysis from laboratory-derived VISA strain. We verified the role of a novel mutation of WalK (I237T) and our results further indicated that the introduction of WalK (I237T) by allelic replacement can confer vancomycin resistance in MSSA with common VISA characteristics, including thickened cell walls, reduced autolysis, and attenuated virulence. Consistent with these phenotypes, real-time quantitative reverse transcription-PCR revealed the altered expression of several genes associated with cell wall metabolism and virulence control. In addition, electrophoretic mobility shift assay indicated that WalR can directly bind to the promoter regions of oatA, sle1, and mgt, fluorescence-based promoter activity and β-galactosidase assays revealed WalK (I237T) can alter promoter activities of oatA, mgt, and sle1, thus regulating genes expression. These findings broaden our understanding of the regulatory network by WalKR system and decipher the molecular mechanisms of developmental VISA resistance in MSSA with point mutations.
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Affiliation(s)
- Jiade Zhu
- Department of Oncology, The First Affiliated Hospital, CAS Key Laboratory of Innate Immunity and Chronic Disease, and Division of Life Sciences and Medicine, University of Science and Technology of China, Anhui, 230027, China
| | - Banghui Liu
- Department of Oncology, The First Affiliated Hospital, CAS Key Laboratory of Innate Immunity and Chronic Disease, and Division of Life Sciences and Medicine, University of Science and Technology of China, Anhui, 230027, China
| | - Xueqin Shu
- Department of Oncology, The First Affiliated Hospital, CAS Key Laboratory of Innate Immunity and Chronic Disease, and Division of Life Sciences and Medicine, University of Science and Technology of China, Anhui, 230027, China
| | - Baolin Sun
- Department of Oncology, The First Affiliated Hospital, CAS Key Laboratory of Innate Immunity and Chronic Disease, and Division of Life Sciences and Medicine, University of Science and Technology of China, Anhui, 230027, China.
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14
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Assoni L, Milani B, Carvalho MR, Nepomuceno LN, Waz NT, Guerra MES, Converso TR, Darrieux M. Resistance Mechanisms to Antimicrobial Peptides in Gram-Positive Bacteria. Front Microbiol 2020; 11:593215. [PMID: 33193264 PMCID: PMC7609970 DOI: 10.3389/fmicb.2020.593215] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 09/03/2020] [Indexed: 02/06/2023] Open
Abstract
With the alarming increase of infections caused by pathogenic multidrug-resistant bacteria over the last decades, antimicrobial peptides (AMPs) have been investigated as a potential treatment for those infections, directly through their lytic effect or indirectly, due to their ability to modulate the immune system. There are still concerns regarding the use of such molecules in the treatment of infections, such as cell toxicity and host factors that lead to peptide inhibition. To overcome these limitations, different approaches like peptide modification to reduce toxicity and peptide combinations to improve therapeutic efficacy are being tested. Human defense peptides consist of an important part of the innate immune system, against a myriad of potential aggressors, which have in turn developed different ways to overcome the AMPs microbicidal activities. Since the antimicrobial activity of AMPs vary between Gram-positive and Gram-negative species, so do the bacterial resistance arsenal. This review discusses the mechanisms exploited by Gram-positive bacteria to circumvent killing by antimicrobial peptides. Specifically, the most clinically relevant genera, Streptococcus spp., Staphylococcus spp., Enterococcus spp. and Gram-positive bacilli, have been explored.
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Affiliation(s)
- Lucas Assoni
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
| | - Barbara Milani
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
| | - Marianna Ribeiro Carvalho
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
| | - Lucas Natanael Nepomuceno
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
| | - Natalha Tedeschi Waz
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
| | - Maria Eduarda Souza Guerra
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
| | - Thiago Rojas Converso
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
| | - Michelle Darrieux
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
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15
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Identification and characterization of mutations responsible for the β-lactam resistance in oxacillin-susceptible mecA-positive Staphylococcus aureus. Sci Rep 2020; 10:16907. [PMID: 33037239 PMCID: PMC7547103 DOI: 10.1038/s41598-020-73796-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 09/20/2020] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus strains that are susceptible to the β-lactam antibiotic oxacillin despite carrying mecA (OS-MRSA) cause serious clinical problems globally because of their ability to easily acquire β-lactam resistance. Understanding the genetic mechanism(s) of acquisition of the resistance is therefore crucial for infection control management. For this purpose, a whole-genome sequencing-based analysis was performed using 43 clinical OS-MRSA strains and 100 mutants with reduced susceptibility to oxacillin (MICs 1.0–256 µg/mL) generated from 26 representative OS-MRSA strains. Genome comparison between the mutants and their respective parent strains identified a total of 141 mutations in 46 genes and 8 intergenic regions. Among them, the mutations are frequently found in genes related to RNA polymerase (rpoBC), purine biosynthesis (guaA, prs, hprT), (p)ppGpp synthesis (relSau), glycolysis (pykA, fbaA, fruB), protein quality control (clpXP, ftsH), and tRNA synthase (lysS, gltX), whereas no mutations existed in mec and bla operons. Whole-genome transcriptional profile of the resistant mutants demonstrated that expression of genes associated with purine biosynthesis, protein quality control, and tRNA synthesis were significantly inhibited similar to the massive transcription downregulation seen in S. aureus during the stringent response, while the levels of mecA expression and PBP2a production were varied. We conclude that a combination effect of mecA upregulation and stringent-like response may play an important role in acquisition of β-lactam resistance in OS-MRSA.
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16
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Yu Y, Huang HL, Ye XQ, Cai DT, Fang JT, Sun J, Liao XP, Liu YH. Synergistic Potential of Antimicrobial Combinations Against Methicillin-Resistant Staphylococcus aureus. Front Microbiol 2020; 11:1919. [PMID: 33013731 PMCID: PMC7461988 DOI: 10.3389/fmicb.2020.01919] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 07/21/2020] [Indexed: 11/13/2022] Open
Abstract
The chemotherapeutic options for methicillin-resistant Staphylococcus aureus (MRSA) infections are limited. Due to the multiple resistant MRSA, therapeutic failure has occurred frequently, even using antibiotics belonging to different categories in clinical scenarios, very recently. This study aimed to investigate the interactions between 11 antibiotics representing different mechanisms of action against MRSA strains and provide therapeutic strategies for clinical infections. Susceptibilities for MRSA strains were determined by broth microdilution or agar dilution according to CLSI guideline. By grouping with each other, a total of 55 combinations were evaluated. The potential synergism was detected through drug interaction assays and further investigated for time-killing curves and an in vivo neutropenic mouse infection model. A total of six combinations (vancomycin with rifampicin, vancomycin with oxacillin, levofloxacin with oxacillin, gentamycin with oxacillin, clindamycin with oxacillin, and clindamycin with levofloxacin) showed synergistic activity against the MRSA ATCC 43300 strain. However, antibacterial activity against clinical isolate #161402 was only observed when vancomycin combined with oxacillin or rifampicin in time-killing assays. Next, therapeutic effectiveness of vancomycin/oxacillin and vancomycin/rifampicin was verified by an in vivo mouse infection model inoculated with #161402. Further investigations on antimicrobial synergism of vancomycin plus oxacillin and vancomycin plus rifampicin against 113 wild-type MRSA strains were evidenced by combined antibiotic MICs and bacterial growth inhibition and in vitro dynamic killing profiles. In summary, vancomycin/rifampicin and vancomycin/oxacillin are the most potential combinations for clinical MRSA infection upon both in vitro and in vivo tests. Other synergetic combinations of levofloxacin/oxacillin, gentamycin/oxacillin, clindamycin/oxacillin, and clindamycin/fosfomycin are also selected but may need more assessment for further application.
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Affiliation(s)
- Yang Yu
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.,National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Han-Liang Huang
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Xin-Qing Ye
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Da-Tong Cai
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Jin-Tao Fang
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Jian Sun
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.,National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Xiao-Ping Liao
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.,National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
| | - Ya-Hong Liu
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.,National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China
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17
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Gostev V, Sopova J, Kalinogorskaya O, Tsvetkova I, Lobzin Y, Klotchenko S, Sidorenko S. In Vitro Ceftaroline Resistance Selection of Methicillin-Resistant Staphylococcus aureus Involves Different Genetic Pathways. Microb Drug Resist 2019; 25:1401-1409. [PMID: 31329022 DOI: 10.1089/mdr.2019.0130] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The pathways in the development of ceftaroline resistance of methicillin-resistant Staphylococcus aureus (MRSA) isolates belonging to the ST8, ST239, and ST228 were evaluated. Ceftaroline-resistant derivatives were isolated through selection during 40 passages. Ceftaroline MIC measurements and whole-genome sequencing were performed after 5, 20, and 40 passages. In two ST8 derivative isolates, ceftaroline MIC increased up to 128 mg/L. Mutations were acquired in gdpP and graS in one isolate after 20 passages and in gdpP in another after 40 passages. MIC for two ST239 derivatives increased to 128 mg/L. Substitutions in Pbp4 and polymorphisms in the upstream region of pbp4 were identified in both derivatives after 40 passages. In one isolate, additional mutation in gdpP and deletion in graR were detected. In an ST228 derivative, MIC increased to 32 mg/L with one mutation in penicillin-binding protein 2a (Y446N) detected after five passages and a second (E447K) after 20 passages. Three pathways in the development of ceftaroline resistance were identified. For ST8 and ST239 derivatives mutations were detected in gdpP and pbp4, respectively, whereas in ST228 - in mecA. Most derivatives harbored additional mutations whose potential role in the development of resistance has not been determined.
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Affiliation(s)
- Vladimir Gostev
- Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, Saint Petersburg, Russia
- Department of Medical Microbiology, North-Western State Medical University named after I.I. Mechnikov, Saint Petersburg, Russia
| | - Julia Sopova
- Laboratory of Genetic Models of Human Diseases, Saint Petersburg Branch of Vavilov Institute of General Genetics, Saint Petersburg, Russia
- Department of Genetics and Biotechnology, Saint Petersburg State University, Saint Petersburg, Russia
| | - Olga Kalinogorskaya
- Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, Saint Petersburg, Russia
| | - Irina Tsvetkova
- Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, Saint Petersburg, Russia
| | - Yuri Lobzin
- Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, Saint Petersburg, Russia
- Department of Medical Microbiology, North-Western State Medical University named after I.I. Mechnikov, Saint Petersburg, Russia
| | - Sergey Klotchenko
- Division of Viral Molecular Biology, Smorodintsev Research Institute of Influenza, Saint Petersburg, Russia
| | - Sergey Sidorenko
- Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, Saint Petersburg, Russia
- Department of Medical Microbiology, North-Western State Medical University named after I.I. Mechnikov, Saint Petersburg, Russia
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18
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Coe KA, Lee W, Stone MC, Komazin-Meredith G, Meredith TC, Grad YH, Walker S. Multi-strain Tn-Seq reveals common daptomycin resistance determinants in Staphylococcus aureus. PLoS Pathog 2019; 15:e1007862. [PMID: 31738809 PMCID: PMC6934316 DOI: 10.1371/journal.ppat.1007862] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 12/27/2019] [Accepted: 09/24/2019] [Indexed: 01/30/2023] Open
Abstract
Antibiotic-resistant Staphylococcus aureus remains a leading cause of antibiotic resistance-associated mortality in the United States. Given the reality of multi-drug resistant infections, it is imperative that we establish and maintain a pipeline of new compounds to replace or supplement our current antibiotics. A first step towards this goal is to prioritize targets by identifying the genes most consistently required for survival across the S. aureus phylogeny. Here we report the first direct comparison of multiple strains of S. aureus via transposon sequencing. We show that mutant fitness varies by strain in key pathways, underscoring the importance of using more than one strain to differentiate between core and strain-dependent essential genes. We treated the libraries with daptomycin to assess whether the strain-dependent differences impact pathways important for survival. Despite baseline differences in gene importance, several pathways, including the lipoteichoic acid pathway, consistently promote survival under daptomycin exposure, suggesting core vulnerabilities that can be exploited to resensitize daptomycin-nonsusceptible isolates. We also demonstrate the merit of using transposons with outward-facing promoters capable of overexpressing nearby genes for identifying clinically-relevant gain-of-function resistance mechanisms. Together, the daptomycin vulnerabilities and resistance mechanisms support a mode of action with wide-ranging effects on the cell envelope and cell division. This work adds to a growing body of literature demonstrating the nuanced insights gained by comparing Tn-Seq results across multiple bacterial strains. Antibiotic-resistant Staphylococcus aureus kills thousands of people every year in the United States alone. To stay ahead of the looming threat of multidrug-resistant infections, we must continue to develop new antibiotics and find ways to make our current repertoire of antibiotics more effective, including by finding pairs of compounds that perform best when administered together. In the age of next-generation sequencing, we can now use transposon sequencing to find potential targets for new antibiotics on a genome-wide scale, identified as either essential genes or genes that positively influence survival in the presence of an antibiotic. In this work, we created a compendium of genes that are essential across a range of S. aureus strains, as well as those that are important for growth in the presence of the antibiotic daptomycin. The results will be a resource for researchers working to develop the next generation of antibiotic therapies.
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Affiliation(s)
- Kathryn A. Coe
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Wonsik Lee
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Madeleine C. Stone
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Gloria Komazin-Meredith
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, Pennsylvania, United States of America
| | - Timothy C. Meredith
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, Pennsylvania, United States of America
- * E-mail: (TCM); (YHG); (SW)
| | - Yonatan H. Grad
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
- Division of Infectious Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (TCM); (YHG); (SW)
| | - Suzanne Walker
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail: (TCM); (YHG); (SW)
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19
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Monk IR, Shaikh N, Begg SL, Gajdiss M, Sharkey LKR, Lee JYH, Pidot SJ, Seemann T, Kuiper M, Winnen B, Hvorup R, Collins BM, Bierbaum G, Udagedara SR, Morey JR, Pulyani N, Howden BP, Maher MJ, McDevitt CA, King GF, Stinear TP. Zinc-binding to the cytoplasmic PAS domain regulates the essential WalK histidine kinase of Staphylococcus aureus. Nat Commun 2019; 10:3067. [PMID: 31296851 PMCID: PMC6624279 DOI: 10.1038/s41467-019-10932-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 06/05/2019] [Indexed: 01/23/2023] Open
Abstract
WalKR (YycFG) is the only essential two-component regulator in the human pathogen Staphylococcus aureus. WalKR regulates peptidoglycan synthesis, but this function alone does not explain its essentiality. Here, to further understand WalKR function, we investigate a suppressor mutant that arose when WalKR activity was impaired; a histidine to tyrosine substitution (H271Y) in the cytoplasmic Per-Arnt-Sim (PASCYT) domain of the histidine kinase WalK. Introducing the WalKH271Y mutation into wild-type S. aureus activates the WalKR regulon. Structural analyses of the WalK PASCYT domain reveal a metal-binding site, in which a zinc ion (Zn2+) is tetrahedrally-coordinated by four amino acids including H271. The WalKH271Y mutation abrogates metal binding, increasing WalK kinase activity and WalR phosphorylation. Thus, Zn2+-binding negatively regulates WalKR. Promoter-reporter experiments using S. aureus confirm Zn2+ sensing by this system. Identification of a metal ligand recognized by the WalKR system broadens our understanding of this critical S. aureus regulon.
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Affiliation(s)
- Ian R Monk
- Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, 3000, Australia.
| | - Nausad Shaikh
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4067, Australia
| | - Stephanie L Begg
- Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, 3000, Australia
| | - Mike Gajdiss
- University Clinics of Bonn, Institute of Medical Microbiology, Immunology and Parasitology, 53127, Bonn, Germany
| | - Liam K R Sharkey
- Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, 3000, Australia
| | - Jean Y H Lee
- Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, 3000, Australia
| | - Sacha J Pidot
- Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, 3000, Australia
| | - Torsten Seemann
- Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, 3000, Australia.,Melbourne Bioinformatics, University of Melbourne, Melbourne, VIC, 3000, Australia
| | | | | | - Rikki Hvorup
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4067, Australia
| | - Brett M Collins
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4067, Australia
| | - Gabriele Bierbaum
- University Clinics of Bonn, Institute of Medical Microbiology, Immunology and Parasitology, 53127, Bonn, Germany
| | - Saumya R Udagedara
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Jacqueline R Morey
- Department of Molecular and Biomedical Sciences, School of Biological Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia
| | - Neha Pulyani
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Benjamin P Howden
- Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, 3000, Australia
| | - Megan J Maher
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia
| | - Christopher A McDevitt
- Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, 3000, Australia.,Department of Molecular and Biomedical Sciences, School of Biological Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4067, Australia
| | - Timothy P Stinear
- Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, 3000, Australia.
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20
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Abstract
Dating back to the 1960s, initial studies on the staphylococcal cell wall were driven by the need to clarify the mode of action of the first antibiotics and the resistance mechanisms developed by the bacteria. During the following decades, the elucidation of the biosynthetic path and primary composition of staphylococcal cell walls was propelled by advances in microbial cell biology, specifically, the introduction of high-resolution analytical techniques and molecular genetic approaches. The field of staphylococcal cell wall gradually gained its own significance as the complexity of its chemical structure and involvement in numerous cellular processes became evident, namely its versatile role in host interactions, coordination of cell division and environmental stress signaling.This chapter includes an updated description of the anatomy of staphylococcal cell walls, paying particular attention to information from the last decade, under four headings: high-resolution analysis of the Staphylococcus aureus peptidoglycan; variations in peptidoglycan composition; genetic determinants and enzymes in cell wall synthesis; and complex functions of cell walls. The latest contributions to a more precise picture of the staphylococcal cell envelope were possible due to recently developed state-of-the-art microscopy and spectroscopy techniques and to a wide combination of -omics approaches, that are allowing to obtain a more integrative view of this highly dynamic structure.
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Affiliation(s)
- Rita Sobral
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
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21
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Basco MDS, Kothari A, McKinzie PB, Revollo JR, Agnihothram S, Azevedo MP, Saccente M, Hart ME. Reduced vancomycin susceptibility and increased macrophage survival in Staphylococcus aureus strains sequentially isolated from a bacteraemic patient during a short course of antibiotic therapy. J Med Microbiol 2019; 68:848-859. [DOI: 10.1099/jmm.0.000988] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- M. D. S. Basco
- 1 Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
| | - A. Kothari
- 2 Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Page B. McKinzie
- 3 Division of Molecular and Genetic Toxicology, NCTR, Food and Drug Administration, Jefferson, Arkansas, USA
| | - J. R. Revollo
- 3 Division of Molecular and Genetic Toxicology, NCTR, Food and Drug Administration, Jefferson, Arkansas, USA
| | - S. Agnihothram
- 1 Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
| | - M. P. Azevedo
- 1 Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
| | - M. Saccente
- 2 Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - M. E. Hart
- 1 Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas, USA
- 4 Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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22
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Identification of a Novel Gene Associated with High-Level β-Lactam Resistance in Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Strain Mu3 and Methicillin-Resistant S. aureus Strain N315. Antimicrob Agents Chemother 2019; 63:AAC.00712-18. [PMID: 30455230 DOI: 10.1128/aac.00712-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 10/25/2018] [Indexed: 12/16/2022] Open
Abstract
β-Lactam resistance levels vary among methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates, mediated by chromosomal mutations and exogenous resistance gene mecA However, MRSA resistance mechanisms are incompletely understood. A P440L mutation in the RNA polymerase β' subunit (RpoC) in slow-vancomycin-intermediate S. aureus (sVISA) strain V6-5 is associated with conversion of heterogeneous VISA (hVISA) to sVISA. In this study, we found a V6-5-derivative strain (L4) with significantly decreased MICs to oxacillin (OX) and vancomycin. Whole-genome sequencing revealed that L4 has nonsense mutations in two genes, relQ, encoding (p)ppGpp synthetase, an alarmone of the stringent response, and a gene of unknown function. relQ deletion in the hVISA strain Mu3 did not affect OX MIC. However, introducing nonsense mutation of the unknown gene into Mu3 decreased OX MIC, whereas wild-type gene recovered high-level resistance. Thus, mutation of this unknown gene (ehoM) decreased β-lactam resistance in Mu3 and L4. Presence of relQ in a multicopy plasmid restored high-level resistance in strain L4 but not in the ehoM mutant Mu3 strain, indicating a genetic interaction between ehoM and relQ depending on the L4 genetic background. While mupirocin (a stringent response inducer) can increase the β-lactam resistance of MRSA, mupirocin supplementation in an ehoM deletion mutant of N315 did not elevate resistance. ehoM expression in N315 was induced by mupirocin, and the relative amount of ehoM transcript in Mu3 was higher than in N315 induced by the stringent response. Our findings indicate that ehoM plays an essential role in high-level β-lactam resistance in MRSA via the stringent response.
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Peng H, Rao Y, Yuan W, Zheng Y, Shang W, Hu Z, Yang Y, Tan L, Xiong K, Li S, Zhu J, Hu X, Hu Q, Rao X. Reconstruction of the Vancomycin-Susceptible Staphylococcus aureus Phenotype From a Vancomycin-Intermediate S. aureus XN108. Front Microbiol 2018; 9:2955. [PMID: 30546356 PMCID: PMC6279853 DOI: 10.3389/fmicb.2018.02955] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 11/16/2018] [Indexed: 11/17/2022] Open
Abstract
The emergence of vancomycin-intermediate Staphylococcus aureus (VISA) has raised healthcare concerns worldwide. VISA is often associated with multiple genetic changes. However, the relative contributions of these changes to VISA phenotypes are incompletely defined. We have characterized VISA XN108 with vancomycin MIC of 12 μg/ml. Genome comparison revealed that WalK(S221P), GraS(T136I), and RpoB(H481N) mutations possibly contributed to the VISA phenotype of XN108. In this study, the above mutations were stepwise cured, and the phenotypes between XN108 and its derivates were compared. We constructed four isogenic mutant strains, XN108-WalK(P221S) (termed as K65), XN108-GraS(I136T) (termed as S65), XN108-RpoB(N481H) (termed as B65), and XN108-WalK(P221S)/GraS(I136T) (termed as KS65), using the allelic replacement experiments with the native alleles derived from a vancomycin-susceptible S. aureus isolate DP65. Antimicrobial susceptibility test revealed K65 and S65 exhibited decreased vancomycin resistance, whereas B65 revealed negligibly differed when compared with the wild-type XN108. Sequentially introducing WalK(P221S) and GraS(I136T) completely converted XN108 into a VSSA phenotype. Transmission electronic microscopy and autolysis determination demonstrated that cell wall thickening and decreasing autolysis were associated with the change of vancomycin resistance levels. Compared with XN108, K65 exhibited 577 differentially expressed genes (DEGs), whereas KS65 presented 555 DEGs. Of those DEGs, 390 were common in K65 and KS65, including those upregulated genes responsible for citrate cycle and bacterial autolysis, and the downregulated genes involved in peptidoglycan biosynthesis and teichoic acid modification. In conclusion, a VSSA phenotype could be completely reconstituted from a VISA strain XN108. WalK(S221P) and GraS(T136I) mutations may work synergistically in conferring vancomycin resistance in XN108.
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Affiliation(s)
- Huagang Peng
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Yifan Rao
- Institute of Modern Biopharmaceuticals, School of Life Sciences, Southwest University, Chongqing, China
| | - Wenchang Yuan
- Department of Clinical Laboratory, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Ying Zheng
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Weilong Shang
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Zhen Hu
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Yi Yang
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Li Tan
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Kun Xiong
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Shu Li
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Junmin Zhu
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Xiaomei Hu
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Qiwen Hu
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
| | - Xiancai Rao
- Department of Microbiology, College of Basic Medical Sciences, Key Laboratory of Microbial Engineering Under the Educational Committee in Chongqing, Army Medical University (Third Military Medical University), Chongqing, China
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McClure JAM, Lakhundi S, Kashif A, Conly JM, Zhang K. Genomic Comparison of Highly Virulent, Moderately Virulent, and Avirulent Strains From a Genetically Closely-Related MRSA ST239 Sub-lineage Provides Insights Into Pathogenesis. Front Microbiol 2018; 9:1531. [PMID: 30042755 PMCID: PMC6048232 DOI: 10.3389/fmicb.2018.01531] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/20/2018] [Indexed: 12/19/2022] Open
Abstract
The genomic comparison of virulent (TW20), moderately virulent (CMRSA6/CMRSA3), and avirulent (M92) strains from a genetically closely-related MRSA ST239 sub-lineage revealed striking similarities in their genomes and antibiotic resistance profiles, despite differences in virulence and pathogenicity. The main differences were in the spa gene (coding for staphylococcal protein A), lpl genes (coding for lipoprotein-like membrane proteins), cta genes (genes involved in heme synthesis), and the dfrG gene (coding for a trimethoprim-resistant dihydrofolate reductase), as well as variations in the presence or content of some prophages and plasmids, which could explain the virulence differences of these strains. TW20 was positive for all genetic traits tested, compared to CMRSA6, CMRSA3, and M92. The major components differing among these strains included spa and lpl with TW20 carrying both whereas CMRSA6/CMRSA3 carry spa identical to TW20 but have a disrupted lpl. M92 is devoid of both these traits. Considering the role played by these components in innate immunity and virulence, it is predicted that since TW20 has both the components intact and functional, these traits contribute to its pathogenesis. However, CMRSA6/CMRSA3 are missing one of these components, hence their intermediately virulent nature. On the contrary, M92 is completely devoid of both the spa and lpl genes and is avirulent. Mobile genetic elements play a potential role in virulence. TW20 carries three prophages (ϕSa6, ϕSa3, and ϕSPβ-like), a pathogenicity island and two plasmids. CMRSA6, CMRSA3, and M92 contain variations in one or more of these components. The virulence associated genes in these components include staphylokinase, entertoxins, antibiotic/antiseptic/heavy metal resistance and bacterial persistence. Additionally, there are many hypothetical proteins (present with variations among strains) with unknown function in these mobile elements which could be making an important contribution in the virulence of these strains. The above mentioned repertoire of virulence components in TW20 likely contributes to its increased virulence, while the absence and/or modification of one or more of these components in CMRSA6/CMRSA3 and M92 likely affects the virulence of the strains.
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Affiliation(s)
- Jo-Ann M. McClure
- Centre for Antimicrobial Resistance, Alberta Health Services/Calgary Laboratory Services/University of Calgary, Calgary, AB, Canada
| | - Sahreena Lakhundi
- Centre for Antimicrobial Resistance, Alberta Health Services/Calgary Laboratory Services/University of Calgary, Calgary, AB, Canada
- Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, AB, Canada
| | - Ayesha Kashif
- Centre for Antimicrobial Resistance, Alberta Health Services/Calgary Laboratory Services/University of Calgary, Calgary, AB, Canada
| | - John M. Conly
- Centre for Antimicrobial Resistance, Alberta Health Services/Calgary Laboratory Services/University of Calgary, Calgary, AB, Canada
- Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, AB, Canada
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
- Department of Medicine, University of Calgary, Calgary, AB, Canada
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - Kunyan Zhang
- Centre for Antimicrobial Resistance, Alberta Health Services/Calgary Laboratory Services/University of Calgary, Calgary, AB, Canada
- Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, AB, Canada
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
- Department of Medicine, University of Calgary, Calgary, AB, Canada
- The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
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Sekyere JO, Asante J. Emerging mechanisms of antimicrobial resistance in bacteria and fungi: advances in the era of genomics. Future Microbiol 2018; 13:241-262. [PMID: 29319341 DOI: 10.2217/fmb-2017-0172] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Bacteria and fungi continue to develop new ways to adapt and survive the lethal or biostatic effects of antimicrobials through myriad mechanisms. Novel antibiotic resistance genes such as lsa(C), erm(44), VCC-1, mcr-1, mcr-2, mcr-3, mcr-4, bla KLUC-3 and bla KLUC-4 were discovered through comparative genomics and further functional studies. As well, mutations in genes that hitherto were unknown to confer resistance to antimicrobials, such as trm, PP2C, rpsJ, HSC82, FKS2 and Rv2887, were shown by genomics and transcomplementation assays to mediate antimicrobial resistance in Acinetobacter baumannii, Staphylococcus aureus, Enterococcus faecium, Saccharomyces cerevisae, Candida glabrata and Mycobacterium tuberculosis, respectively. Thus, genomics, transcriptomics and metagenomics, coupled with functional studies are the future of antimicrobial resistance research and novel drug discovery or design.
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Affiliation(s)
- John Osei Sekyere
- Faculty of Pharmacy & Pharmaceutical Sciences, Kwame Nkrumah University of Science & Technology, Kumasi, Ghana
| | - Jonathan Asante
- Faculty of Pharmacy & Pharmaceutical Sciences, Kwame Nkrumah University of Science & Technology, Kumasi, Ghana
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26
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Staphylococcus aureus Sequences from Osteomyelitic Specimens of a Pathological Bone Collection from Pre-Antibiotic Times. DIVERSITY-BASEL 2017. [DOI: 10.3390/d9040043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Peng H, Hu Q, Shang W, Yuan J, Zhang X, Liu H, Zheng Y, Hu Z, Yang Y, Tan L, Li S, Hu X, Li M, Rao X. WalK(S221P), a naturally occurring mutation, confers vancomycin resistance in VISA strain XN108. J Antimicrob Chemother 2017; 72:1006-1013. [PMID: 27999059 DOI: 10.1093/jac/dkw518] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/03/2016] [Indexed: 02/06/2023] Open
Abstract
Objectives Vancomycin-intermediate Staphylococcus aureus (VISA) strains have spread globally. We previously isolated an ST239 VISA (XN108) with a vancomycin MIC of 12 mg/L. The mechanism for XN108 resistance to vancomycin was investigated in this study. Methods Genome comparison was performed to characterize mutations that might contribute to the XN108 resistance phenotype. The novel mutation WalK(S221P) was identified and investigated using allelic replacement experiments. Vancomycin susceptibilities, autolytic activities and morphologies of the strains were examined. Autophosphorylation activities of WalK and the WalK(S221P) mutant were determined in vitro with [λ- 32 P]ATP, and binding activity of WalK(S221P)-activated WalR to the promoter region of its target gene lytM was determined by electrophoretic mobility shift assay. Results Genome comparison revealed three mutations, GraS(T136I), RpoB(H481N) and WalK(S221P), which might be responsible for vancomycin resistance in XN108. The introduction of WalK(S221P) to the vancomycin-susceptible strain N315 increased its vancomycin MIC from 1.5 to 8 mg/L, whereas the allelic replacement of WalK(S221P) with the native N315 WalK allele in XN108 decreased its vancomycin MIC from 12 to 4 mg/L. The VISA strains have thickened cell walls and decreased autolysis, consistent with observed changes in the expression of genes involved in cell wall metabolism and virulence regulation. WalK(S221P) exhibited reduced autophosphorylation, which may lead to reduced phosphorylation of WalR. WalK(S221P)-phosphorylated WalR also exhibited a reduced capacity to bind to the lytM promoter. Conclusions The naturally occurring WalK(S221P) mutation plays a key role in vancomycin resistance in XN108.
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Cameron DR, Lin YH, Trouillet-Assant S, Tafani V, Kostoulias X, Mouhtouris E, Skinner N, Visvanathan K, Baines SL, Howden B, Monk IR, Laurent F, Stinear TP, Howden BP, Peleg AY. Vancomycin-intermediate Staphylococcus aureus isolates are attenuated for virulence when compared with susceptible progenitors. Clin Microbiol Infect 2017; 23:767-773. [PMID: 28396035 DOI: 10.1016/j.cmi.2017.03.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 03/29/2017] [Accepted: 03/30/2017] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Vancomycin-intermediate Staphylococcus aureus (VISA) is associated with genetic changes that may also impact upon pathogenicity. In the current study, we compared the virulence of clinical VISA strains with their isogenic vancomycin-susceptible progenitors (VSSA). METHODS Production of the critical virulence protein, α toxin, was assessed using Western blot analysis and was correlated to agr activity using a bioluminescent agr-reporter. Cytotoxicity and intracellular persistence were compared ex vivo for VSSA and VISA within non-professional phagocytes (NPP). Virulence and host immune responses were further explored in vivo using a murine model of bacteraemia. RESULTS VISA isolates produced up to 20-fold less α toxin compared with VSSA, and this was corroborated by either loss of agr activity due to agr mutation, or altered agr activity in the absence of mutation. VISA were less cytotoxic towards NPP and were associated with enhanced intracellular persistence, suggesting that NPP may act as a reservoir for VISA. Infection with VSSA strains produced higher mortality in a murine bacteraemia model (≥90% 7-day mortality) compared with infection with VISA isolates (20% to 50%, p <0.001). Mice infected with VISA produced a dampened immune response (4.6-fold reduction in interleukin-6, p <0.001) and persistent organ bacterial growth was observed for VISA strains out to 7 days. CONCLUSIONS These findings highlight the remarkable adaptability of S. aureus, whereby, in addition to having reduced antibiotic susceptibility, VISA alter the expression of pathogenic factors to circumvent the host immune response to favour persistent infection over acute virulence.
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Affiliation(s)
- D R Cameron
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Australia
| | - Y-H Lin
- Department of Microbiology and Immunology, The University of Melbourne at the Doherty Institute of Infection & Immunity, Australia
| | - S Trouillet-Assant
- Department of Microbiology, French National Reference Centre for Staphylococci, Hospices Civils de Lyon, International Centre of Infectiology Research, France
| | - V Tafani
- Department of Microbiology, French National Reference Centre for Staphylococci, Hospices Civils de Lyon, International Centre of Infectiology Research, France
| | - X Kostoulias
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Australia
| | - E Mouhtouris
- Department of Surgery, The University of Melbourne, Australia
| | - N Skinner
- Department of Medicine, The University of Melbourne, Australia
| | - K Visvanathan
- Department of Medicine, The University of Melbourne, Australia
| | - S L Baines
- Department of Microbiology and Immunology, The University of Melbourne at the Doherty Institute of Infection & Immunity, Australia
| | - B Howden
- Department of Microbiology and Immunology, The University of Melbourne at the Doherty Institute of Infection & Immunity, Australia
| | - I R Monk
- Department of Microbiology and Immunology, The University of Melbourne at the Doherty Institute of Infection & Immunity, Australia
| | - F Laurent
- Department of Microbiology, French National Reference Centre for Staphylococci, Hospices Civils de Lyon, International Centre of Infectiology Research, France
| | - T P Stinear
- Department of Microbiology and Immunology, The University of Melbourne at the Doherty Institute of Infection & Immunity, Australia
| | - B P Howden
- Department of Microbiology and Immunology, The University of Melbourne at the Doherty Institute of Infection & Immunity, Australia; Infectious Diseases and Microbiology Departments, Austin Health, Australia.
| | - A Y Peleg
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Australia; Department of Infectious Diseases, The Alfred Hospital and Central Clinical School, Monash University, Australia.
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Wang Y, Li X, Jiang L, Han W, Xie X, Jin Y, He X, Wu R. Novel Mutation Sites in the Development of Vancomycin- Intermediate Resistance in Staphylococcus aureus. Front Microbiol 2017; 7:2163. [PMID: 28119680 PMCID: PMC5222870 DOI: 10.3389/fmicb.2016.02163] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 12/22/2016] [Indexed: 11/13/2022] Open
Abstract
Increased use of vancomycin has led to the emergence of vancomycin-intermediate Staphylococcus aureus (VISA). To investigate the mechanism of VISA development, 39 methicillin-susceptible strains and 3 MRSA strains were treated with vancomycin to induce non-susceptibility, and mutations in six genes were analyzed. All the strains were treated with vancomycin in vitro for 60 days. MICs were determined by the agar dilution and E-test methods. Vancomycin was then removed to assess the stability of VISA strains and mutations. Following 60 days of vancomycin treatment in vitro, 29/42 VISA strains were generated. The complete sequences of rpoB, vraS, graR, graS, walK, and walR were compared with those in the parental strains. Seven missense mutations including four novel mutations (L466S in rpoB, R232K in graS, I594M in walk, and A111T in walR) were detected frequently in strains with vancomycin MIC ≥ 12 μg/mL. Jonckheere-Terpstra trend test indicated these mutations might play an important role during VISA evolution. After the vancomycin treatment, strains were passaged to vancomycin-free medium for another 60 days, and the MICs of all strains decreased. Our results suggest that rpoB, graS, walk, and walR are more important than vraS and graR in VISA development.
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Affiliation(s)
- Yubing Wang
- College of Biological Sciences and Biotechnology, Beijing Forestry University Beijing, China
| | - Xiaoli Li
- College of Biological Sciences and Biotechnology, Beijing Forestry University Beijing, China
| | - Libo Jiang
- College of Biological Sciences and Biotechnology, Beijing Forestry UniversityBeijing, China; Center for Computational Biology, Beijing Forestry UniversityBeijing, China
| | - Wentao Han
- College of Biological Sciences and Biotechnology, Beijing Forestry University Beijing, China
| | - Xiangming Xie
- College of Biological Sciences and Biotechnology, Beijing Forestry University Beijing, China
| | - Yi Jin
- College of Biological Sciences and Biotechnology, Beijing Forestry UniversityBeijing, China; Center for Computational Biology, Beijing Forestry UniversityBeijing, China
| | - Xiaoqing He
- College of Biological Sciences and Biotechnology, Beijing Forestry UniversityBeijing, China; Center for Computational Biology, Beijing Forestry UniversityBeijing, China
| | - Rongling Wu
- College of Biological Sciences and Biotechnology, Beijing Forestry UniversityBeijing, China; Center for Computational Biology, Beijing Forestry UniversityBeijing, China; Center for Statistical Genetics, Pennsylvania State UniversityHershey, PA, USA
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30
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Hardt P, Engels I, Rausch M, Gajdiss M, Ulm H, Sass P, Ohlsen K, Sahl HG, Bierbaum G, Schneider T, Grein F. The cell wall precursor lipid II acts as a molecular signal for the Ser/Thr kinase PknB of Staphylococcus aureus. Int J Med Microbiol 2016; 307:1-10. [PMID: 27989665 DOI: 10.1016/j.ijmm.2016.12.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 11/22/2016] [Accepted: 12/10/2016] [Indexed: 12/23/2022] Open
Abstract
The assembly of the bacterial cell wall requires synchronization of a multitude of biosynthetic machineries and regulatory networks. The eukaryotic-like serine/threonine kinase PknB has been implicated in coordinating cross-wall formation, autolysis and cell division in Staphylococcus aureus. However, the signal molecule sensed by this kinase remained elusive so far. Here, we provide compelling biochemical evidence that PknB interacts with the ultimate cell wall precursor lipid II, triggering kinase activity. Moreover, we observed crosstalk of PknB with the two component system WalKR and identified the early cell division protein FtsZ as another PknB phosphorylation substrate in S. aureus. In agreement with the implied role in regulation of cell envelope metabolism, we found PknB to preferentially localize to the septum of S. aureus and the PASTA domains to be crucial for recruitment to this site. The data provide a model for the contribution of PknB to control cell wall metabolism and cell division.
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Affiliation(s)
- Patrick Hardt
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany
| | - Ina Engels
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany; German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
| | - Marvin Rausch
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany; German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
| | - Mike Gajdiss
- Institute of Medical Microbiology, Immunology and Parasitology, University of Bonn, Bonn, Germany
| | - Hannah Ulm
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany
| | - Peter Sass
- Interfaculty Institute for Microbiology and Infection Medicine, Department for Microbial Bioactive Compounds, University of Tuebingen, Tuebingen, Germany
| | - Knut Ohlsen
- Institute for Molecular Infection Biology, University of Wuerzburg, Wuerzburg, Germany
| | - Hans-Georg Sahl
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany; Institute of Medical Microbiology, Immunology and Parasitology, University of Bonn, Bonn, Germany
| | - Gabriele Bierbaum
- Institute of Medical Microbiology, Immunology and Parasitology, University of Bonn, Bonn, Germany
| | - Tanja Schneider
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany; German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany.
| | - Fabian Grein
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany; German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany.
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Tan XE, Neoh HM, Looi ML, Chin SF, Cui L, Hiramatsu K, Hussin S, Jamal R. Activated ADI pathway: the initiator of intermediate vancomycin resistance in Staphylococcus aureus. Can J Microbiol 2016; 63:260-264. [PMID: 28059579 DOI: 10.1139/cjm-2016-0439] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Comparative proteomic profiling between 2 vancomycin-intermediate Staphylococcus aureus (VISA) strains, Mu50Ω-vraSm and Mu50Ω-vraSm-graRm, and vancomycin-susceptible S. aureus (VSSA) strain Mu50Ω revealed upregulated levels of catabolic ornithine carbamoyltransferase (ArcB) of the arginine catabolism pathway in VISA strains. Subsequent analyses showed that the VISA strains have higher levels of cellular ATP and ammonia, which are by-products of arginine catabolism, and displayed thicker cell walls. We postulate that elevated cytoplasmic ammonia and ATP molecules, resulting from activated arginine catabolism upon acquisition of vraS and graR mutations, are important requirements facilitating cell wall biosynthesis, thereby contributing to thickened cell wall and consequently reduced vancomycin susceptibility in VISA strains.
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Affiliation(s)
- Xin-Ee Tan
- a UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Malaysia
| | - Hui-Min Neoh
- a UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Malaysia.,b Department of Bacteriology, School of Medicine, Juntendo University, Japan
| | - Mee-Lee Looi
- a UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Malaysia.,c Taylor's University Lakeside Campus, School of Biosciences, Malaysia
| | - Siok Fong Chin
- a UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Malaysia
| | - Longzhu Cui
- d Division of Bacteriology, Department of Infection and Immunity, School of Medicine, Jichi Medical University, Japan
| | - Keiichi Hiramatsu
- b Department of Bacteriology, School of Medicine, Juntendo University, Japan
| | - Salasawati Hussin
- e Department of Medical Microbiology and Immunology, Universiti Kebangsaan Malaysia, Malaysia
| | - Rahman Jamal
- a UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Malaysia
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32
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Hu Q, Peng H, Rao X. Molecular Events for Promotion of Vancomycin Resistance in Vancomycin Intermediate Staphylococcus aureus. Front Microbiol 2016; 7:1601. [PMID: 27790199 PMCID: PMC5062060 DOI: 10.3389/fmicb.2016.01601] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 09/26/2016] [Indexed: 12/14/2022] Open
Abstract
Vancomycin has been used as the last resort in the clinical treatment of serious Staphylococcus aureus infections. Vancomycin-intermediate S. aureus (VISA) was discovered almost two decades ago. Aside from the vancomycin-intermediate phenotype, VISA strains from the clinic or laboratory exhibited common characteristics, such as thickened cell walls, reduced autolysis, and attenuated virulence. However, the genetic mechanisms responsible for the reduced vancomycin susceptibility in VISA are varied. The comparative genomics of vancomycin-susceptible S. aureus (VSSA)/VISA pairs showed diverse genetic mutations in VISA; only a small number of these mutations have been experimentally verified. To connect the diversified genotypes and common phenotypes in VISA, we reviewed the genetic alterations in the relative determinants, including mutations in the vraTSR, graSR, walKR, stk1/stp1, rpoB, clpP, and cmk genes. Especially, we analyzed the mechanism through which diverse mutations mediate vancomycin resistance. We propose a unified model that integrates diverse gene functions and complex biochemical processes in VISA upon the action of vancomycin.
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Affiliation(s)
- Qiwen Hu
- Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University Chongqing, China
| | - Huagang Peng
- Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University Chongqing, China
| | - Xiancai Rao
- Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University Chongqing, China
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Kim JW, Kim HK, Kang GS, Kim IH, Kim HS, Lee YS, Yoo JI. The SAV1322 gene from Staphylococcus aureus: genomic and proteomic approaches to identification and characterization of gene function. BMC Microbiol 2016; 16:206. [PMID: 27599615 PMCID: PMC5013637 DOI: 10.1186/s12866-016-0824-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 08/29/2016] [Indexed: 11/18/2022] Open
Abstract
Background Bacterial two-component regulatory systems (TCRS) are associated with the expression of virulence factors and antibiotic susceptibility. In Staphylococcus aureus, 16 TCRS types have been identified. The histidine kinase/response regulator SAV1321/SAV1322 in the S. aureus shares considerable homology with the TCRS DesKR in Bacillus subtilis. However, a function for the SAV1322 locus has not yet been assigned. Results Deletion of the SAV1322 locus in S. aureus results in reduced growth when cultured under low (25 °C) and high (46 °C) temperature conditions. The sav1322 deletion mutant is more tolerant to oxidative stress in vitro and is less pathogenic in a murine infection model when compared with wild-type parent strain Mu50. Furthermore, the sav1322 mutant exhibits lower MICs for gentimicin, tetracyclines and glycopeptides, increased autolysis, and a thinner cell wall when compared with the wild-type strain. Microarray and proteomic analyses show that the expression of cell-wall-associated genes glmS and murZ are lower, and the expression of heat shock and stress-related genes (hrcA, ctsR, dnaK, dnaJ, grpE, clpB, and clpC) are higher in the sav1322 mutant when compared with the wild-type strain. In addition, the sav1322 mutant displays altered expression of proteins involved in carbohydrate/energy metabolism, cell wall metabolism, and stress or heat shock response, as well as other metabolic processes including lipid metabolism, amino acid biosynthesis, purine or pyrimidine metabolism, transcription, and protein biosynthesis. Conclusions The S. aureus SAV1322 locus plays a pronounced role in temperature adaptation, antibiotic resistance, and virulence by regulating a wide range of genes and proteins involved in metabolism and stress tolerance. Electronic supplementary material The online version of this article (doi:10.1186/s12866-016-0824-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jung Wook Kim
- Division of Antimicrobial Resistance, Center for Infectious Diseases, National Research Institute of Health, Centers for Disease Control and Prevention, Cheongju, South Korea
| | - Hyun-Kyung Kim
- Division of Antimicrobial Resistance, Center for Infectious Diseases, National Research Institute of Health, Centers for Disease Control and Prevention, Cheongju, South Korea
| | - Gi Su Kang
- Division of Antimicrobial Resistance, Center for Infectious Diseases, National Research Institute of Health, Centers for Disease Control and Prevention, Cheongju, South Korea
| | - Il-Hwan Kim
- Division of Antimicrobial Resistance, Center for Infectious Diseases, National Research Institute of Health, Centers for Disease Control and Prevention, Cheongju, South Korea
| | - Hwa Su Kim
- Division of Antimicrobial Resistance, Center for Infectious Diseases, National Research Institute of Health, Centers for Disease Control and Prevention, Cheongju, South Korea
| | - Yeong Seon Lee
- Division of Antimicrobial Resistance, Center for Infectious Diseases, National Research Institute of Health, Centers for Disease Control and Prevention, Cheongju, South Korea
| | - Jae Il Yoo
- Division of Antimicrobial Resistance, Center for Infectious Diseases, National Research Institute of Health, Centers for Disease Control and Prevention, Cheongju, South Korea. .,Korea National Research Institute of Health, Osong Health Technology Administration Complex, 187, Osongsaengmyeong2-ro, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do, 363-700, South Korea.
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Population Genomics of Reduced Vancomycin Susceptibility in Staphylococcus aureus. mSphere 2016; 1:mSphere00094-16. [PMID: 27446992 PMCID: PMC4954867 DOI: 10.1128/msphere.00094-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/23/2016] [Indexed: 01/22/2023] Open
Abstract
The increased prevalence of vancomycin-intermediate Staphylococcus aureus (VISA) is an emerging health care threat. Genome-based comparative methods hold great promise to uncover the genetic basis of the VISA phenotype, which remains obscure. S. aureus isolates were collected from a single individual that presented with recurrent staphylococcal bacteremia at three time points, and the isolates showed successively reduced levels of vancomycin susceptibility. A population genomic approach was taken to compare patient S. aureus isolates with decreasing vancomycin susceptibility across the three time points. To do this, patient isolates were sequenced to high coverage (~500×), and sequence reads were used to model site-specific allelic variation within and between isolate populations. Population genetic methods were then applied to evaluate the overall levels of variation across the three time points and to identify individual variants that show anomalous levels of allelic change between populations. A successive reduction in the overall levels of population genomic variation was observed across the three time points, consistent with a population bottleneck resulting from antibiotic treatment. Despite this overall reduction in variation, a number of individual mutations were swept to high frequency in the VISA population. These mutations were implicated as potentially involved in the VISA phenotype and interrogated with respect to their functional roles. This approach allowed us to identify a number of mutations previously implicated in VISA along with allelic changes within a novel class of genes, encoding LPXTG motif-containing cell-wall-anchoring proteins, which shed light on a novel mechanistic aspect of vancomycin resistance. IMPORTANCE The emergence and spread of antibiotic resistance among bacterial pathogens are two of the gravest threats to public health facing the world today. We report the development and application of a novel population genomic technique aimed at uncovering the evolutionary dynamics and genetic determinants of antibiotic resistance in Staphylococcus aureus. This method was applied to S. aureus cultures isolated from a single patient who showed decreased susceptibility to the vancomycin antibiotic over time. Our approach relies on the increased resolution afforded by next-generation genome-sequencing technology, and it allowed us to discover a number of S. aureus mutations, in both known and novel gene targets, which appear to have evolved under adaptive pressure to evade vancomycin mechanisms of action. The approach we lay out in this work can be applied to resistance to any number of antibiotics across numerous species of bacterial pathogens.
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Draft Genome Sequences of Vancomycin-Intermediate Staphylococcus aureus Strains in South Korea. GENOME ANNOUNCEMENTS 2016; 4:4/3/e00027-16. [PMID: 27313284 PMCID: PMC4911463 DOI: 10.1128/genomea.00027-16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report here the draft genome sequences of four vancomycin-intermediate Staphylococcus aureus (VISA) strains from South Korean hospitals participating in a nationwide laboratory surveillance program for vancomycin-intermediate and vancomycin-resistant Staphylococcus aureus. All strains harbor mutations in the walKR, graSR, and/or rpoB genes that are known frequently mutated determinants of VISA.
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Complete Reconstitution of the Vancomycin-Intermediate Staphylococcus aureus Phenotype of Strain Mu50 in Vancomycin-Susceptible S. aureus. Antimicrob Agents Chemother 2016; 60:3730-42. [PMID: 27067329 PMCID: PMC4879404 DOI: 10.1128/aac.00420-16] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/01/2016] [Indexed: 12/23/2022] Open
Abstract
Complete reconstitution of the vancomycin-intermediate Staphylococcus aureus (VISA) phenotype of strain Mu50 was achieved by sequentially introducing mutations into six genes of vancomycin-susceptible S. aureus (VSSA) strain N315ΔIP. The six mutated genes were detected in VISA strain Mu50 but not in N315ΔIP. Introduction of the mutation Ser329Leu into vraS, encoding the sensor histidine kinase of the vraSR two-component regulatory (TCR) system, and another mutation, Glu146Lys, into msrR, belonging to the LytR-CpsA-Psr (LCP) family, increased the level of vancomycin resistance to that detected in heterogeneous vancomycin-intermediate S. aureus (hVISA) strain Mu3. Introduction of two more mutations, Asn197Ser into graR of the graSR TCR system and His481Tyr into rpoB, encoding the β subunit of RNA polymerase, converted the hVISA strain into a VISA strain with the same level of vancomycin resistance as Mu50. Surprisingly, however, the constructed quadruple mutant strain ΔIP4 did not have a thickened cell wall, a cardinal feature of the VISA phenotype. Subsequent study showed that cell wall thickening was an inducible phenotype in the mutant strain, whereas it was a constitutive one in Mu50. Finally, introduction of the Ala297Val mutation into fdh2, which encodes a putative formate dehydrogenase, or a 67-amino-acid sequence deletion into sle1 [sle1(Δ67aa)], encoding the hydrolase of N-acetylmuramyl-l-alanine amidase in the peptidoglycan, converted inducible cell wall thickening into constitutive cell wall thickening. sle1(Δ67aa) was found to cause a drastic decrease in autolysis activity. Thus, all six mutated genes required for acquisition of the VISA phenotype were directly or indirectly involved in the regulation of cell physiology. The VISA phenotype seemed to be achieved through multiple genetic events accompanying drastic changes in cell physiology.
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Whole-Genome Sequencing for Routine Pathogen Surveillance in Public Health: a Population Snapshot of Invasive Staphylococcus aureus in Europe. mBio 2016; 7:mBio.00444-16. [PMID: 27150362 PMCID: PMC4959656 DOI: 10.1128/mbio.00444-16] [Citation(s) in RCA: 141] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The implementation of routine whole-genome sequencing (WGS) promises to transform our ability to monitor the emergence and spread of bacterial pathogens. Here we combined WGS data from 308 invasive Staphylococcus aureus isolates corresponding to a pan-European population snapshot, with epidemiological and resistance data. Geospatial visualization of the data is made possible by a generic software tool designed for public health purposes that is available at the project URL (http://www.microreact.org/project/EkUvg9uY?tt=rc). Our analysis demonstrates that high-risk clones can be identified on the basis of population level properties such as clonal relatedness, abundance, and spatial structuring and by inferring virulence and resistance properties on the basis of gene content. We also show that in silico predictions of antibiotic resistance profiles are at least as reliable as phenotypic testing. We argue that this work provides a comprehensive road map illustrating the three vital components for future molecular epidemiological surveillance: (i) large-scale structured surveys, (ii) WGS, and (iii) community-oriented database infrastructure and analysis tools. The spread of antibiotic-resistant bacteria is a public health emergency of global concern, threatening medical intervention at every level of health care delivery. Several recent studies have demonstrated the promise of routine whole-genome sequencing (WGS) of bacterial pathogens for epidemiological surveillance, outbreak detection, and infection control. However, as this technology becomes more widely adopted, the key challenges of generating representative national and international data sets and the development of bioinformatic tools to manage and interpret the data become increasingly pertinent. This study provides a road map for the integration of WGS data into routine pathogen surveillance. We emphasize the importance of large-scale routine surveys to provide the population context for more targeted or localized investigation and the development of open-access bioinformatic tools to provide the means to combine and compare independently generated data with publicly available data sets.
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Rapid Emergence and Evolution of Staphylococcus aureus Clones Harboring fusC-Containing Staphylococcal Cassette Chromosome Elements. Antimicrob Agents Chemother 2016; 60:2359-65. [PMID: 26856837 PMCID: PMC4808225 DOI: 10.1128/aac.03020-15] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 01/22/2016] [Indexed: 01/12/2023] Open
Abstract
The prevalence of fusidic acid (FA) resistance among Staphylococcus aureus strains in New Zealand (NZ) is among the highest reported globally, with a recent study describing a resistance rate of approximately 28%. Three FA-resistant S. aureus clones (ST5 MRSA, ST1 MSSA, and ST1 MRSA) have emerged over the past decade and now predominate in NZ, and in all three clones FA resistance is mediated by the fusC gene. In particular, ST5 MRSA has rapidly become the dominant MRSA clone in NZ, although the origin of FA-resistant ST5 MRSA has not been explored, and the genetic context of fusC in FA-resistant NZ isolates is unknown. To better understand the rapid emergence of FA-resistant S. aureus, we used population-based comparative genomics to characterize a collection of FA-resistant and FA-susceptible isolates from NZ. FA-resistant NZ ST5 MRSA displayed minimal genetic diversity and represented a phylogenetically distinct clade within a global population model of clonal complex 5 (CC5) S. aureus. In all lineages, fusC was invariably located within staphylococcal cassette chromosome (SCC) elements, suggesting that SCC-mediated horizontal transfer is the primary mechanism of fusC dissemination. The genotypic association of fusC with mecA has important implications for the emergence of MRSA clones in populations with high usage of fusidic acid. In addition, we found that fusC was colocated with a recently described virulence factor (tirS) in dominant NZ S. aureus clones, suggesting a fitness advantage. This study points to the likely molecular mechanisms responsible for the successful emergence and spread of FA-resistant S. aureus.
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Khosa S, Hoeppner A, Gohlke H, Schmitt L, Smits SHJ. Structure of the Response Regulator NsrR from Streptococcus agalactiae, Which Is Involved in Lantibiotic Resistance. PLoS One 2016; 11:e0149903. [PMID: 26930060 PMCID: PMC4773095 DOI: 10.1371/journal.pone.0149903] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 02/05/2016] [Indexed: 01/22/2023] Open
Abstract
Lantibiotics are antimicrobial peptides produced by Gram-positive bacteria. Interestingly, several clinically relevant and human pathogenic strains are inherently resistant towards lantibiotics. The expression of the genes responsible for lantibiotic resistance is regulated by a specific two-component system consisting of a histidine kinase and a response regulator. Here, we focused on a response regulator involved in lantibiotic resistance, NsrR from Streptococcus agalactiae, and determined the crystal structures of its N-terminal receiver domain and C-terminal DNA-binding effector domain. The C-terminal domain exhibits a fold that classifies NsrR as a member of the OmpR/PhoB subfamily of regulators. Amino acids involved in phosphorylation, dimerization, and DNA-binding were identified and demonstrated to be conserved in lantibiotic resistance regulators. Finally, a model of the full-length NsrR in the active and inactive state provides insights into protein dimerization and DNA-binding.
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Affiliation(s)
- Sakshi Khosa
- Institute of Biochemistry, Heinrich Heine University Duesseldorf, Universitaetsstr. 1, 40225, Duesseldorf, Germany
| | - Astrid Hoeppner
- X-Ray Facility and Crystal Farm, Heinrich Heine University Duesseldorf, Universitaetsstr. 1, 40225, Duesseldorf, Germany
| | - Holger Gohlke
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Duesseldorf, Universitaetsstr. 1, 40225, Duesseldorf, Germany
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich Heine University Duesseldorf, Universitaetsstr. 1, 40225, Duesseldorf, Germany
| | - Sander H. J. Smits
- Institute of Biochemistry, Heinrich Heine University Duesseldorf, Universitaetsstr. 1, 40225, Duesseldorf, Germany
- * E-mail:
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Ishii K, Tabuchi F, Matsuo M, Tatsuno K, Sato T, Okazaki M, Hamamoto H, Matsumoto Y, Kaito C, Aoyagi T, Hiramatsu K, Kaku M, Moriya K, Sekimizu K. Phenotypic and genomic comparisons of highly vancomycin-resistant Staphylococcus aureus strains developed from multiple clinical MRSA strains by in vitro mutagenesis. Sci Rep 2015; 5:17092. [PMID: 26603341 PMCID: PMC4658547 DOI: 10.1038/srep17092] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 10/01/2015] [Indexed: 12/12/2022] Open
Abstract
The development of vancomycin (VCM) resistance in Staphylococcus aureus threatens global health. Studies of the VCM-resistance mechanism and alternative therapeutic strategies are urgently needed. We mutagenized S. aureus laboratory strains and methicillin-resistant S. aureus (MRSA) with ethyl methanesulfonate, and isolated mutants that exhibited high resistance to VCM (minimum inhibitory concentration = 32 μg/ml). These VCM-resistant strains were sensitive to linezolid and rifampicin, and partly to arbekacin and daptomycin. Beta-lactams had synergistic effects with VCM against these mutants. VCM-resistant strains exhibited a 2-fold increase in the cell wall thickness. Several genes were commonly mutated among the highly VCM-resistant mutants. These findings suggest that MRSA has a potential to develop high VCM resistance with cell wall thickening by the accumulation of mutations.
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Affiliation(s)
- Kenichi Ishii
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Fumiaki Tabuchi
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Miki Matsuo
- Department of Bacteriology, Faculty of Medicine, Juntendo University, Tokyo, Japan
| | - Keita Tatsuno
- Department of Infection Control and Prevention, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Tomoaki Sato
- Department of Infection Control and Prevention, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Mitsuhiro Okazaki
- Department of Medical Technology, School of Health Sciences, Tokyo University of Technology, Tokyo, Japan
| | - Hiroshi Hamamoto
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Yasuhiko Matsumoto
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Chikara Kaito
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Tetsuji Aoyagi
- Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Tokyo, Japan
| | - Keiichi Hiramatsu
- Department of Bacteriology, Faculty of Medicine, Juntendo University, Tokyo, Japan
| | - Mitsuo Kaku
- Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Tokyo, Japan
| | - Kyoji Moriya
- Department of Infection Control and Prevention, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kazuhisa Sekimizu
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
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Abstract
"Heteroresistance" describes a phenomenon where subpopulations of seemingly isogenic bacteria exhibit a range of susceptibilities to a particular antibiotic. Unfortunately, a lack of standard methods to determine heteroresistance has led to inappropriate use of this term. Heteroresistance has been recognized since at least 1947 and occurs in Gram-positive and Gram-negative bacteria. Its clinical relevance may be considerable, since more resistant subpopulations may be selected during antimicrobial therapy. However, the use of nonstandard methods to define heteroresistance, which are costly and involve considerable labor and resources, precludes evaluating the clinical magnitude and severity of this phenomenon. We review the available literature on antibiotic heteroresistance and propose recommendations for definitions and determination criteria for heteroresistant bacteria. This will help in assessing the global clinical impact of heteroresistance and developing uniform guidelines for improved therapeutic outcomes.
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Lee JY, Howden BP. Vancomycin in the treatment of methicillin-resistant Staphylococcus aureus - a clinician's guide to the science informing current practice. Expert Rev Anti Infect Ther 2015; 13:855-69. [PMID: 25947636 DOI: 10.1586/14787210.2015.1041924] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Clinicians treating an infection assess a patient in terms of disease manifestation, causative organism and available antibiotic options with the aim of devising a therapeutic strategy under the creed of 'first, do no harm'. It is often only when treatment is failing or options are limited, as in the scenario of multidrug-resistant organisms, that consideration is given to the interplay that occurs between the microbe and the host. The emergence of Staphylococcus aureus with reduced susceptibility to vancomycin provides a prime example of these dynamic interactions. This review shall explore these concepts in relation to vancomycin for the treatment of methicillin-resistant S. aureus, with the aim of providing an informed approach to the utilization of this drug.
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Affiliation(s)
- Jean Yh Lee
- Microbiological Diagnostic Unit Public Health Laboratory, Department of Microbiology and Immunology, The University of Melbourne at the Doherty Institute for Infection and Immunity, Parkville, 3010, Victoria, Australia
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Joo HS, Otto M. Mechanisms of resistance to antimicrobial peptides in staphylococci. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:3055-61. [PMID: 25701233 DOI: 10.1016/j.bbamem.2015.02.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/06/2015] [Accepted: 02/07/2015] [Indexed: 10/24/2022]
Abstract
Staphylococci are commensal bacteria living on the epithelial surfaces of humans and other mammals. Many staphylococci, including the dangerous pathogen Staphylococcus aureus, can cause severe disease when they breach the epithelial barrier. Both during their commensal life and during infection, staphylococci need to evade mechanisms of innate host defense, of which antimicrobial peptides (AMPs) play a key role in particular on the skin. Mechanisms that staphylococci have developed to evade the bactericidal activity of AMPs are manifold, comprising repulsion of AMPs via alteration of cell wall and membrane surface charges, proteolytic inactivation, sequestration, and secretion. Furthermore, many staphylococci form biofilms, which represents an additional way of protection from antimicrobial agents, including AMPs. Finally, staphylococci can sense the presence of AMPs by sensor/regulator systems that control many of those resistance mechanisms. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.
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Affiliation(s)
- Hwang-Soo Joo
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases (NIAID), U.S. National Institutes of Health (NIH), Bethesda, MD, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases (NIAID), U.S. National Institutes of Health (NIH), Bethesda, MD, USA.
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The Role of Two-Component Signal Transduction Systems in Staphylococcus aureus Virulence Regulation. Curr Top Microbiol Immunol 2015; 409:145-198. [PMID: 26728068 DOI: 10.1007/82_2015_5019] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Staphylococcus aureus is a versatile, opportunistic human pathogen that can asymptomatically colonize a human host but can also cause a variety of cutaneous and systemic infections. The ability of S. aureus to adapt to such diverse environments is reflected in the presence of complex regulatory networks fine-tuning metabolic and virulence gene expression. One of the most widely distributed mechanisms is the two-component signal transduction system (TCS) which allows a pathogen to alter its gene expression profile in response to environmental stimuli. The simpler TCSs consist of only a transmembrane histidine kinase (HK) and a cytosolic response regulator. S. aureus encodes a total of 16 conserved pairs of TCSs that are involved in diverse signalling cascades ranging from global virulence gene regulation (e.g. quorum sensing by the Agr system), the bacterial response to antimicrobial agents, cell wall metabolism, respiration and nutrient sensing. These regulatory circuits are often interconnected and affect each other's expression, thus fine-tuning staphylococcal gene regulation. This manuscript gives an overview of the current knowledge of staphylococcal environmental sensing by TCS and its influence on virulence gene expression and virulence itself. Understanding bacterial gene regulation by TCS can give major insights into staphylococcal pathogenicity and has important implications for knowledge-based drug design and vaccine formulation.
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Mechanism of reduced vancomycin susceptibility conferred by walK mutation in community-acquired methicillin-resistant Staphylococcus aureus strain MW2. Antimicrob Agents Chemother 2014; 59:1352-5. [PMID: 25451044 DOI: 10.1128/aac.04290-14] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Point mutations with unclear molecular mechanisms are often associated with vancomycin resistance in Staphylococcus aureus. Here, we observed that the walK (G223D) mutation caused decreased expression of genes associated with cell wall metabolism, decreased autolytic activity, thickened cell walls, and reduced vancomycin susceptibility. A phosphorylation assay showed that WalK (G223D) exhibited reduced autophosphorylation, which led to reduced phosphorylation of WalR. An electrophoretic mobility shift assay indicated that WalK (G223D)-phosphorylated WalR had a reduced capacity to bind to the atlA promoter.
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Hiramatsu K, Kayayama Y, Matsuo M, Aiba Y, Saito M, Hishinuma T, Iwamoto A. Vancomycin-intermediate resistance in Staphylococcus aureus. J Glob Antimicrob Resist 2014; 2:213-224. [DOI: 10.1016/j.jgar.2014.04.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 04/11/2014] [Accepted: 04/22/2014] [Indexed: 10/25/2022] Open
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Hiramatsu K, Katayama Y, Matsuo M, Sasaki T, Morimoto Y, Sekiguchi A, Baba T. Multi-drug-resistant Staphylococcus aureus and future chemotherapy. J Infect Chemother 2014; 20:593-601. [PMID: 25172776 DOI: 10.1016/j.jiac.2014.08.001] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/31/2014] [Accepted: 08/01/2014] [Indexed: 11/17/2022]
Abstract
Staphylococcus (S.) aureus silently stays as our natural flora, and yet sometimes threatens our life as a tenacious pathogen. In addition to its ability to outwit our immune system, its multi-drug resistance phenotype makes it one of the most intractable pathogenic bacteria in the history of antibiotic chemotherapy. It conquered practically all the antibiotics that have been developed since 1940s. In 1961, the first MRSA was found among S. aureus clinical isolates. Then MRSA prevailed throughout the world as a multi-resistant hospital pathogen. In 1997, MRSA strain Mu50 with reduced susceptibility to vancomycin was isolated. Vancomycin-intermediate S. aureus (VISA), so named according to the CLSI criteria, was the product of adaptive mutation of S. aureus against vancomycin that had long been the last resort to MRSA infection. Here, we describe the genetic basis for the remarkable ability of S. aureus to acquire multi-antibiotic resistance, and propose a novel paradigm for future chemotherapy against the multi-resistant pathogens.
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Affiliation(s)
- K Hiramatsu
- Research Center for Infection Control Science, Juntendo University, 2-1-1 Hongo, Bunkyo-Ku, Tokyo, Japan.
| | - Y Katayama
- Research Center for Infection Control Science, Juntendo University, 2-1-1 Hongo, Bunkyo-Ku, Tokyo, Japan
| | - M Matsuo
- Research Center for Infection Control Science, Juntendo University, 2-1-1 Hongo, Bunkyo-Ku, Tokyo, Japan
| | - T Sasaki
- Research Center for Infection Control Science, Juntendo University, 2-1-1 Hongo, Bunkyo-Ku, Tokyo, Japan
| | - Y Morimoto
- Research Center for Infection Control Science, Juntendo University, 2-1-1 Hongo, Bunkyo-Ku, Tokyo, Japan
| | - A Sekiguchi
- Research Center for Infection Control Science, Juntendo University, 2-1-1 Hongo, Bunkyo-Ku, Tokyo, Japan
| | - T Baba
- Research Center for Infection Control Science, Juntendo University, 2-1-1 Hongo, Bunkyo-Ku, Tokyo, Japan
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48
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Glycopeptide antibiotics: Back to the future. J Antibiot (Tokyo) 2014; 67:631-44. [DOI: 10.1038/ja.2014.111] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 07/17/2014] [Accepted: 07/18/2014] [Indexed: 12/22/2022]
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Draft Genomes of Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Strain MM66 and MM66 Derivatives with Altered Vancomycin Resistance Levels. GENOME ANNOUNCEMENTS 2014; 2:2/4/e00688-14. [PMID: 25013145 PMCID: PMC4110754 DOI: 10.1128/genomea.00688-14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The draft genomes of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) strain MM66 and MM66 isolates demonstrating altered vancomycin resistance levels were produced in an effort to provide information on mutations contributing to the vancomycin resistance levels observed in these strains.
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50
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"Slow VISA," a novel phenotype of vancomycin resistance, found in vitro in heterogeneous vancomycin-intermediate Staphylococcus aureus strain Mu3. Antimicrob Agents Chemother 2014; 58:5024-35. [PMID: 24841271 DOI: 10.1128/aac.02470-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) clinical strain Mu3 spontaneously generates VISA strains at an extremely high frequency (≥1×10(-6)). The generated VISA strains usually grow more slowly than does the parent hVISA strain, but they form colonies on vancomycin-containing agar plates before 48 h of incubation. However, we noticed a curious group of VISA strains, designated "slow VISA" (sVISA), whose colonies appear only after 72 h of incubation. They have extremely prolonged doubling times but have vancomycin MICs of 8 to ∼24 mg/liter when determined after 72 to ∼144 h of incubation. We established strain Mu3-6R-P (6R-P), which has a vancomycin MIC of 16 mg/liter (at 72 h), as a representative sVISA strain. Its cell wall was thickened and autolytic activity was decreased compared to the respective qualities of the parent hVISA strain Mu3. Whole-genome sequencing of 6R-P revealed only one mutation, encoded by rpoB (R512P), which replaced the 512th arginine of the RNA polymerase β-subunit with proline. Its VISA phenotype was unstable, and the strain frequently reverted to hVISA with concomitant losses of pinpoint colony morphology and cell wall thickness and reduced autolytic activity. Sequencing of the rpoB genes of the phenotypic revertant strains revealed mutations affecting the 512th codon, where the proline of 6R-P was replaced with leucine, serine, or histidine. Slow VISA generated in the tissues of an infected patient serves as a temporary shelter for hVISA to survive vancomycin therapy. The sVISA strain spontaneously returns to hVISA when the threat of vancomycin is lifted. The rpoB(R512P) mutation may be regarded as a regulatory mutation that switches the reversible phenotype of sVISA on and off.
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