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Manoharadas S, Al-Rayes BF, Almuzaini MAM, Almohammadi YM. Resensitisation of Methicillin-Resistant Staphylococcus aureus to Conventional Antibiotics in the Presence of an Engineered Enzybiotic. Pharmaceutics 2023; 15:2511. [PMID: 37896271 PMCID: PMC10610342 DOI: 10.3390/pharmaceutics15102511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 10/19/2023] [Accepted: 10/20/2023] [Indexed: 10/29/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most dreadful pathogens relevant in community and nosocomial-related infections around the world. Resensitising MRSA to antibiotics, once it became resistant, was a tough choice due to the high adaptability of this bacteria to savage conditions. This study aimed to create a chimeric enzybiotic against MRSA and test its efficiency, either individually or in combination with antibiotics. The novel enzybiotic BAC100 was constructed by fusing the catalytic domain from the bacteriocin BacL1 from Enterococcus faecalis with the cell-wall-binding domain from protein P17 of Staphylococcus aureus bacteriophage ϕ44AHJD. Apart from its partial lone activity, BAC100 was found to resensitise the MRSA strain to traditional antibiotics, including ampicillin and tetracycline. Both drugs were able to reduce live MRSA cells by 85 and 90%, respectively, within 60 min of treatment together with BAC100. However, no significant activity was observed against MRSA when these drugs were tested independently, pointing to the inherent resistance of MRSA against these conventional antibiotics. To our knowledge, this is one of the first instances where an engineered enzybiotic was found to resensitise MRSA to conventional antibiotics. This study will pave the way for the development of similar peptides that can be used together with antibiotics against gruesome pathogens of clinical importance.
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Affiliation(s)
- Salim Manoharadas
- Central Laboratory, College of Science, King Saud University, P.O. Box 2454, Riyadh 11451, Saudi Arabia; (B.F.A.-R.); (M.A.M.A.); (Y.M.A.)
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Lade H, Kim JS. Molecular Determinants of β-Lactam Resistance in Methicillin-Resistant Staphylococcus aureus (MRSA): An Updated Review. Antibiotics (Basel) 2023; 12:1362. [PMID: 37760659 PMCID: PMC10525618 DOI: 10.3390/antibiotics12091362] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 08/21/2023] [Accepted: 08/24/2023] [Indexed: 09/29/2023] Open
Abstract
The development of antibiotic resistance in Staphylococcus aureus, particularly in methicillin-resistant S. aureus (MRSA), has become a significant health concern worldwide. The acquired mecA gene encodes penicillin-binding protein 2a (PBP2a), which takes over the activities of endogenous PBPs and, due to its low affinity for β-lactam antibiotics, is the main determinant of MRSA. In addition to PBP2a, other genetic factors that regulate cell wall synthesis, cell signaling pathways, and metabolism are required to develop high-level β-lactam resistance in MRSA. Although several genetic factors that modulate β-lactam resistance have been identified, it remains unclear how they alter PBP2a expression and affect antibiotic resistance. This review describes the molecular determinants of β-lactam resistance in MRSA, with a focus on recent developments in our understanding of the role of mecA-encoded PBP2a and on other genetic factors that modulate the level of β-lactam resistance. Understanding the molecular determinants of β-lactam resistance can aid in developing novel strategies to combat MRSA.
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Affiliation(s)
| | - Jae-Seok Kim
- Department of Laboratory Medicine, Hallym University College of Medicine, Kangdong Sacred Heart Hospital, Seoul 05355, Republic of Korea;
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Synergistic Combinations of FDA-Approved Drugs with Ceftobiprole against Methicillin-Resistant Staphylococcus aureus. Microbiol Spectr 2023; 11:e0372622. [PMID: 36519895 PMCID: PMC9927495 DOI: 10.1128/spectrum.03726-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
New strategies are urgently needed to address the public health threat of antimicrobial resistance. Synergistic agent combinations provide one possible pathway toward addressing this need and are also of fundamental mechanistic interest. Effective methods for comprehensively identifying synergistic agent combinations are required for such efforts. In this study, an FDA-approved drug library was screened against methicillin-resistant Staphylococcus aureus (MRSA) (ATCC 43300) in the absence and presence of sub-MIC levels of ceftobiprole, a PBP2a-targeted anti-MRSA β-lactam. This screening identified numerous potential synergistic agent combinations, which were then confirmed and characterized for synergy using checkerboard analyses. The initial group of synergistic agents (sum of the minimum fractional inhibitory concentration ∑FICmin ≤0.5) were all β-lactamase-resistant β-lactams (cloxacillin, dicloxacillin, flucloxacillin, oxacillin, nafcillin, and cefotaxime). Cloxacillin-the agent with the greatest synergy with ceftobiprole-is also highly synergistic with ceftaroline, another PBP2a-targeted β-lactam. Further follow-up studies revealed a range of ceftobiprole synergies with other β-lactams, including with imipenem, meropenem, piperacillin, tazobactam, and cefoxitin. Interestingly, given that essentially all other ceftobiprole-β-lactam combinations showed synergy, ceftaroline and ceftobiprole showed no synergy. Modest to no synergy (0.5 < ∑FICmin ≤ 1.0) was observed for several non-β-lactam agents, including vancomycin, daptomycin, balofloxacin, and floxuridine. Mupirocin had antagonistic activity with ceftobiprole. Flucloxacillin appeared particularly promising, with both a low intrinsic MIC and good synergy with ceftobiprole. That so many β-lactam combinations with ceftobiprole show synergy suggests that β-lactam combinations can generally increase β-lactam effectiveness and may also be useful in reducing resistance emergence and spread in MRSA. IMPORTANCE Antimicrobial resistance represents a serious threat to public health. Antibacterial agent combinations provide a potential approach to combating this problem, and synergistic agent combinations-in which each agent enhances the antimicrobial activity of the other-are particularly valuable in this regard. Ceftobiprole is a late-generation β-lactam antibiotic developed for MRSA infections. Resistance has emerged to ceftobiprole, jeopardizing this agent's effectiveness. To identify synergistic agent combinations with ceftobiprole, an FDA-approved drug library was screened for potential synergistic combinations with ceftobiprole. This screening and follow-up studies identified numerous β-lactams with ceftobiprole synergy.
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Wu Z, Chan B, Low J, Chu JJH, Hey HWD, Tay A. Microbial resistance to nanotechnologies: An important but understudied consideration using antimicrobial nanotechnologies in orthopaedic implants. Bioact Mater 2022; 16:249-270. [PMID: 35415290 PMCID: PMC8965851 DOI: 10.1016/j.bioactmat.2022.02.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 12/11/2022] Open
Abstract
Microbial resistance to current antibiotics therapies is a major cause of implant failure and adverse clinical outcomes in orthopaedic surgery. Recent developments in advanced antimicrobial nanotechnologies provide numerous opportunities to effective remove resistant bacteria and prevent resistance from occurring through unique mechanisms. With tunable physicochemical properties, nanomaterials can be designed to be bactericidal, antifouling, immunomodulating, and capable of delivering antibacterial compounds to the infection region with spatiotemporal accuracy. Despite its substantial advancement, an important, but under-explored area, is potential microbial resistance to nanomaterials and how this can impact the clinical use of antimicrobial nanotechnologies. This review aims to provide a better understanding of nanomaterial-associated microbial resistance to accelerate bench-to-bedside translations of emerging nanotechnologies for effective control of implant associated infections.
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Affiliation(s)
- Zhuoran Wu
- Institute of Health Innovation & Technology, National University of Singapore, 117599, Singapore
| | - Brian Chan
- Department of Biomedical Engineering, National University of Singapore, 117583, Singapore
| | - Jessalyn Low
- Department of Biomedical Engineering, National University of Singapore, 117583, Singapore
| | - Justin Jang Hann Chu
- Biosafety Level 3 Core Facility, Yong Loo Lin School of Medicine, National University of Singapore, 117599, Singapore
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545, Singapore
- Infectious Disease Programme, Yong Loo Lin School of Medicine, National University of Singapore, 117547, Singapore
- Institute of Molecular and Cell Biology, 35 Agency for Science, Technology and Research, 138673, Singapore
| | - Hwee Weng Dennis Hey
- National University Health System, National University of Singapore, 119228, Singapore
| | - Andy Tay
- Institute of Health Innovation & Technology, National University of Singapore, 117599, Singapore
- Department of Biomedical Engineering, National University of Singapore, 117583, Singapore
- Tissue Engineering Programme, National University of Singapore, 117510, Singapore
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Shafique L, Aqib AI, Liang Q, Qin C, Ali MM, Adil M, Sarwar Z, Saleem A, Ajmal M, Khan A, Pan H, Cui K, Liu Q. Genomic and Therapeutic Analyses of Staphylococcus aureus Isolated from Cattle Reproductive Tract. BIOMED RESEARCH INTERNATIONAL 2022; 2022:6240711. [PMID: 36147637 PMCID: PMC9489358 DOI: 10.1155/2022/6240711] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 08/09/2022] [Indexed: 11/25/2022]
Abstract
Staphylococcus aureus is emerging as a ubiquitous multidrug-resistant pathogen circulating among animals, humans, and their environment. The current study focused on molecular epidemiology and evidence-based treatment against S. aureus from bovine endometritis. For this study, n = 304 cattle were screened for endometritis using ultrasonography while presenting case history, and clinical signs were also considered. S. aureus was isolated from endometritis-positive uterine samples which were further put to molecular identification, phylogenetic analysis, susceptibility to antibiotics, and testing of novel drug combinations in both in vitro and field trials. The findings of the study revealed 78.20% of bovine endometritis samples positive for S. aureus, while nuc gene-based genotyping of S. aureus thermal nuclease (SA-1, SA-2, and SA-3) showed close relatedness with S. aureus thermal nuclease of Bos taurus. Drug combinations showed 5.00 to 188.88% rise in zones of inhibitions (ZOI) for drugs used in combination compared to the drugs used alone. Gentamicin in combination with amoxicillin and enrofloxacin with metronidazol showed synergistic interactions in an in vitro trial. Co-amoxiclav with gentamicin, gentamicin with enrofloxacin, and metronidazole with enrofloxacin showed 100%, 80%, and 60% efficacy in treating clinical cases in field trials, respectively. As a result, the study came to the conclusion the higher prevalence of endometritis-based S. aureus, genetic host shifts, narrow options for single drugs, and need for novel drug combinations to treat clinical cases.
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Affiliation(s)
- Laiba Shafique
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding School of Life Science and Engineering, Foshan University, Foshan 528225, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, Guangxi 530005, China
| | - Amjad Islam Aqib
- Department of Medicine, Cholistan University of Veterianry and Animal Sciences, Bahawalpur 63100, Pakistan
| | - Qin Liang
- Jinan City Zhangqiu District Animal Husbandry and Veterinary Development Center, China
| | - Chaobin Qin
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, Guangxi 530005, China
| | - Muhammad Muddassir Ali
- Institute of Biochemistry and Biotechnology, University of Veterinary and Animal Sciences, Lahore 54000, Pakistan
| | - Memoona Adil
- Institute of Biochemistry and Biotechnology, University of Veterinary and Animal Sciences, Lahore 54000, Pakistan
| | - Zaeem Sarwar
- Department of Theriogenology, Cholistan University of Veterinary and Animal Sciences, Bahawalpur-63100, Pakistan
| | - Arslan Saleem
- Department of Aerospace and Geodesy, Technical University of Munich, Arcisstra. 21, 80333 Munich, Germany
| | - Muhammad Ajmal
- Department of Veterinary Medicine, Sindh Agriculture University, Tandojam 70060, Pakistan
| | - Alveena Khan
- Allama Iqbal Medical College Lahore (University of Health Sciences), 54770, Pakistan
| | - Hongping Pan
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, Guangxi 530005, China
| | - Kuiqing Cui
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding School of Life Science and Engineering, Foshan University, Foshan 528225, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, Guangxi 530005, China
| | - Qingyou Liu
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding School of Life Science and Engineering, Foshan University, Foshan 528225, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, Guangxi 530005, China
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Impact of the Stringent Stress Response on the Expression of Methicillin Resistance in Staphylococcaceae Strains Carrying mecA, mecA1 and mecC. Antibiotics (Basel) 2022; 11:antibiotics11020255. [PMID: 35203858 PMCID: PMC8868139 DOI: 10.3390/antibiotics11020255] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 02/09/2022] [Accepted: 02/14/2022] [Indexed: 02/05/2023] Open
Abstract
The acquisition of the resistance determinant mecA by Staphylococcus aureus is of major clinical importance, since it confers a resistant phenotype to virtually the entire large family of structurally diverse β-lactam antibiotics. While the common resistance determinant mecA is essential, the optimal expression of the resistance phenotype also requires additional factors. Previous studies showed that the great majority of clinical isolates of methicillin-resistant S. aureus (MRSA) have a heterogeneous resistant phenotype, and we observed that strains carrying methicillin genetic determinants other than mecA also produce similar heterogeneous phenotypes. All these strains were able to express high and homogeneous levels of oxacillin resistance when sub-inhibitory concentrations of mupirocin, an effector of the stringent stress response, were added to growth media. Our studies show that the gene gmk, involved in guanine metabolism, was one of the first genes to exhibit mutations in homoresistant (H*R) derivatives obtained through serial passages (with increasing concentrations of oxacillin) of the prototype mecC-carrying MRSA strain LGA251. All these observations led us to propose that a common molecular mechanism for the establishment of high and homogeneous oxacillin resistance must be present among isolates carrying different methicillin resistance determinants. In this work, we tested this hypothesis using whole-genome sequencing (WGS) to compare isogenic populations differing only in their degrees of oxacillin resistance and carrying various methicillin genetic determinants
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Ftsh Sensitizes Methicillin-Resistant Staphylococcus aureus to β-Lactam Antibiotics by Degrading YpfP, a Lipoteichoic Acid Synthesis Enzyme. Antibiotics (Basel) 2021; 10:antibiotics10101198. [PMID: 34680778 PMCID: PMC8532640 DOI: 10.3390/antibiotics10101198] [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: 08/21/2021] [Revised: 09/17/2021] [Accepted: 09/27/2021] [Indexed: 12/20/2022] Open
Abstract
In the Gram-positive pathogen Staphylococcus aureus, FtsH, a membrane-bound metalloprotease, plays a critical role in bacterial virulence and stress resistance. This protease is also known to sensitize methicillin-resistant Staphylococcus aureus (MRSA) to β-lactam antibiotics; however, the molecular mechanism is not known. Here, by the analysis of FtsH substrate mutants, we found that FtsH sensitizes MRSA specifically to β-lactams by degrading YpfP, the enzyme synthesizing the anchor molecule for lipoteichoic acid (LTA). Both the overexpression of FtsH and the disruption of ypfP-sensitized MRSA to β-lactams were observed. The knockout mutation in ftsH and ypfP increased the thickness of the cell wall. The β-lactam sensitization coincided with the production of aberrantly large LTA molecules. The combination of three mutations in the rpoC, vraB, and SAUSA300_2133 genes blocked the β-lactam-sensitizing effect of FtsH. Murine infection with the ypfP mutant could be treated by oxacillin, a β-lactam antibiotic ineffective against MRSA; however, the effective concentration of oxacillin differed depending on the S. aureus strain. Our study demonstrated that the β-lactam sensitizing effect of FtsH is due to its digestion of YpfP. It also suggests that the larger LTA molecules are responsible for the β-lactam sensitization phenotype, and YpfP is a viable target for developing novel anti-MRSA drugs.
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Giulieri SG, Tong SYC, Williamson DA. Using genomics to understand meticillin- and vancomycin-resistant Staphylococcus aureus infections. Microb Genom 2020; 6:e000324. [PMID: 31913111 PMCID: PMC7067033 DOI: 10.1099/mgen.0.000324] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 12/12/2019] [Indexed: 12/15/2022] Open
Abstract
Resistance to meticillin and vancomycin in Staphylococcus aureus significantly complicates the management of severe infections like bacteraemia, endocarditis or osteomyelitis. Here, we review the molecular mechanisms and genomic epidemiology of resistance to these agents, with a focus on how genomics has provided insights into the emergence and evolution of major meticillin-resistant S. aureus clones. We also provide insights on the use of bacterial whole-genome sequencing to inform management of S. aureus infections and for control of transmission at the hospital and in the community.
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Affiliation(s)
- Stefano G. Giulieri
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
- Infectious Disease Department, Austin Health, Melbourne, Australia
| | - Steven Y. C. Tong
- Victorian Infectious Disease Service, Royal Melbourne Hospital, and Doherty Department University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Victoria, Australia
- Menzies School of Health Research, Darwin, Australia
| | - Deborah A. Williamson
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
- Microbiological Diagnostic Unit Public Health Laboratory, University of Melbourne at the Peter Doherty Institute of Infection and Immunity, Melbourne, Australia
- Microbiology, Royal Melbourne Hospital, Melbourne, Australia
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Antimicrobial resistance in methicillin-resistant Staphylococcus aureus to newer antimicrobial agents. Antimicrob Agents Chemother 2019:AAC.01216-19. [PMID: 31527033 DOI: 10.1128/aac.01216-19] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) result in significant morbidity and mortality for patients in both community and health care settings. This is primarily due to the difficulty in treating MRSA, which is often resistant to multiple classes of antibiotics. Understanding the mechanisms of antimicrobial resistance (AMR) in MRSA provides insight into the optimal use of antimicrobial agents in clinical practice and also underpins critical aspects of antimicrobial stewardship programs. In this review we delineate the mechanisms, prevalence, and clinical importance of resistance to antibiotics licensed in the past 20 years that target MRSA, as well as new drugs in the pipeline which are likely to be licensed soon. Current gaps in scientific knowledge about MRSA resistance mechanisms are discussed, and topics in the epidemiology of AMR in S. aureus that require further investigation are highlighted.
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Hobbs JK, Boraston AB. (p)ppGpp and the Stringent Response: An Emerging Threat to Antibiotic Therapy. ACS Infect Dis 2019; 5:1505-1517. [PMID: 31287287 DOI: 10.1021/acsinfecdis.9b00204] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In 1969, Cashel and Gallant first observed the presence of (p)ppGpp-the signaling molecule of the stringent response-in starved bacterial cells. Fifty years later, (p)ppGpp and the stringent response have emerged as essential master regulators of not only the bacterial response to stress but also almost all aspects of bacterial physiology, virulence, and immune evasion. More worryingly, a wealth of data now indicate that (p)ppGpp and stringent response activation pose a serious threat to the efficacy and clinical success of antimicrobial therapy. Here, we focus on the central role that (p)ppGpp and the stringent response play in the phenomenon of antibiotic tolerance, as well as the acquisition, development, and expression of antibiotic resistance. We review these consequences of stringent response activation in relation to the main proteins involved in (p)ppGpp production and control, in particular the complex interplay between monofunctional and bifunctional long RelA/SpoT homologues (RSHs) and small alarmone synthetases (SASs). We also review the growing evidence to suggest that there are multiple other indirect pathways of stringent response induction that can affect antibiotic efficacy. Finally, we summarize recent studies that indicate the in vivo and clinical impact of (p)ppGpp production on antibiotic treatment outcomes. We conclude by reviewing the progress to date in the search for novel therapeutics that target the stringent response.
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Affiliation(s)
- Joanne K. Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
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Molecular Characterization of Equine Staphylococcus aureus Isolates Exhibiting Reduced Oxacillin Susceptibility. Toxins (Basel) 2019; 11:toxins11090535. [PMID: 31540335 PMCID: PMC6783909 DOI: 10.3390/toxins11090535] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 09/08/2019] [Accepted: 09/09/2019] [Indexed: 01/15/2023] Open
Abstract
The detection of borderline oxacillin-resistant Staphylococcus aureus (BORSA) represents a challenge to both, veterinary and human laboratories. Between 2015 and 2017, 19 equine S. aureus with elevated minimal inhibitory concentrations for oxacillin were detected in routine diagnostics. The aim of this study was to characterize these isolates to identify factors possibly associated with the BORSA phenotype. All S. aureus were subjected to antimicrobial susceptibility testing and whole genome sequencing (WGS). A quantifiable β-lactamase activity assay was performed for a representative subset of 13 isolates. The WGS data analysis of the 19 BORSA isolates identified two different genomic lineages, sequence type (ST) 1 and ST1660. The core genome multilocus sequence typing (cgMLST) revealed a close relatedness of all isolates belonging to either ST1 or ST1660. The WGS analysis identified the resistance genes aadD, dfrG, tet(L), and/or blaZ and aacA-aphD. Phenotypic resistance to penicillins, aminoglycosides, tetracyclines, fluoroquinolones and sulfamethoxazole/trimethoprim was observed in the respective isolates. For the penicillin-binding proteins 1-4, amino acid substitutions were predicted using WGS data. Since neither transglycosylase nor transpeptidase domains were affected, these alterations might not explain the BORSA phenotype. Moreover, β-lactamase activity was found to be associated with an inducible blaZ gene. The lineage-specific differences regarding the expression profiles were noted.
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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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Methicillin-Resistant Staphylococcus aureus Nasal Colonization among Healthcare Workers at Kampala International University Teaching Hospital, Southwestern Uganda. CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY 2019; 2019:4157869. [PMID: 30984319 PMCID: PMC6431477 DOI: 10.1155/2019/4157869] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 12/17/2018] [Accepted: 02/11/2019] [Indexed: 01/02/2023]
Abstract
Whereas Staphylococcus aureus is a pathogen, it colonizes healthy people as normal flora without causing any symptoms or illness. Probably because of greater exposure, healthcare workers (HCWs) are more colonized, serving as reservoir for endogenous infections as well as dissemination. In developing countries including Uganda, there is scarcity of the literature on S. aureus carriage among HCWs, making infection control difficult. This study aimed at determining the nasal carriage rate and comparing the antimicrobial susceptibility profiles of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA) isolates from HCWs of Kampala International University Teaching Hospital. Nasal swab specimens from HCWs were screened for MRSA using both phenotypic and genotypic methods. Antimicrobial susceptibility testing of the MRSA and MSSA isolates was performed using the Kirby–Bauer disc diffusion method. Out of the 97 participants, 28 (28.8%) participants were nasal carriers of S. aureus of which 13 (46.4%) were phenotypically MRSA (resistant to cefoxitin) and 8 (28.6%) were genotypically MRSA (had mecA gene). Only 6 isolates of the 13 isolates (46%) which showed resistance to cefoxitin had mecA gene detectable while 2 (13.3%) of the 15 cefoxitin susceptible isolates were found to carry mecA gene. The study thus shows that methicillin resistance in S. aureus may not only be determined by mecA gene.
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Lee AS, de Lencastre H, Garau J, Kluytmans J, Malhotra-Kumar S, Peschel A, Harbarth S. Methicillin-resistant Staphylococcus aureus. Nat Rev Dis Primers 2018; 4:18033. [PMID: 29849094 DOI: 10.1038/nrdp.2018.33] [Citation(s) in RCA: 736] [Impact Index Per Article: 122.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Since the 1960s, methicillin-resistant Staphylococcus aureus (MRSA) has emerged, disseminated globally and become a leading cause of bacterial infections in both health-care and community settings. However, there is marked geographical variation in MRSA burden owing to several factors, including differences in local infection control practices and pathogen-specific characteristics of the circulating clones. Different MRSA clones have resulted from the independent acquisition of staphylococcal cassette chromosome mec (SCCmec), which contains genes encoding proteins that render the bacterium resistant to most β-lactam antibiotics (such as methicillin), by several S. aureus clones. The success of MRSA is a consequence of the extensive arsenal of virulence factors produced by S. aureus combined with β-lactam resistance and, for most clones, resistance to other antibiotic classes. Clinical manifestations of MRSA range from asymptomatic colonization of the nasal mucosa to mild skin and soft tissue infections to fulminant invasive disease with high mortality. Although treatment options for MRSA are limited, several new antimicrobials are under development. An understanding of colonization dynamics, routes of transmission, risk factors for progression to infection and conditions that promote the emergence of resistance will enable optimization of strategies to effectively control MRSA. Vaccine candidates are also under development and could become an effective prevention measure.
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Affiliation(s)
- Andie S Lee
- Departments of Infectious Diseases and Microbiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia.,Faculty of Medicine, University of Sydney, Sydney, New South Wales, Australia
| | - Hermínia de Lencastre
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, NY, USA.,Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Javier Garau
- Department of Medicine, Hospital Universitari Mutua de Terrassa, Barcelona, Spain
| | - Jan Kluytmans
- Department of Infection Control, Amphia Hospital, Breda, Netherlands.,Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Surbhi Malhotra-Kumar
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, Universiteit Antwerpen, Wilrijk, Belgium
| | - Andreas Peschel
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology Department, University of Tübingen, Tübingen, Germany.,German Center for Infection Research, Partner Site Tübingen, Tübingen, Germany
| | - Stephan Harbarth
- Infection Control Programme, University of Geneva Hospitals and Faculty of Medicine, WHO Collaborating Center, Geneva, Switzerland
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Genetic Determinants of High-Level Oxacillin Resistance in Methicillin-Resistant Staphylococcus aureus. Antimicrob Agents Chemother 2018; 62:AAC.00206-18. [PMID: 29555636 DOI: 10.1128/aac.00206-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/11/2018] [Indexed: 12/20/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) strains carry either a mecA- or a mecC-mediated mechanism of resistance to beta-lactam antibiotics, and the phenotypic expression of resistance shows extensive strain-to-strain variation. In recent communications, we identified the genetic determinants associated with the stringent stress response that play a major role in the antibiotic resistant phenotype of the historically earliest "archaic" clone of MRSA and in the mecC-carrying MRSA strain LGA251. Here, we sought to test whether or not the same genetic determinants also contribute to the resistant phenotype of highly and homogeneously resistant (H*R) derivatives of a major contemporary MRSA clone, USA300. We found that the resistance phenotype was linked to six genes (fruB, gmk, hpt, purB, prsA, and relA), which were most frequently targeted among the analyzed 20 H*R strains (one mutation per clone in 19 of the 20 H*R strains). Besides the strong parallels with our previous findings (five of the six genes matched), all but one of the repeatedly targeted genes were found to be linked to guanine metabolism, pointing to the key role that this pathway plays in defining the level of antibiotic resistance independent of the clonal type of MRSA.
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