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Singh G, Rana A, Smriti. Decoding antimicrobial resistance: unraveling molecular mechanisms and targeted strategies. Arch Microbiol 2024; 206:280. [PMID: 38805035 DOI: 10.1007/s00203-024-03998-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 05/29/2024]
Abstract
Antimicrobial resistance poses a significant global health threat, necessitating innovative approaches for combatting it. This review explores various mechanisms of antimicrobial resistance observed in various strains of bacteria. We examine various strategies, including antimicrobial peptides (AMPs), novel antimicrobial materials, drug delivery systems, vaccines, antibody therapies, and non-traditional antibiotic treatments. Through a comprehensive literature review, the efficacy and challenges of these strategies are evaluated. Findings reveal the potential of AMPs in combating resistance due to their unique mechanisms and lower propensity for resistance development. Additionally, novel drug delivery systems, such as nanoparticles, show promise in enhancing antibiotic efficacy and overcoming resistance mechanisms. Vaccines and antibody therapies offer preventive measures, although challenges exist in their development. Non-traditional antibiotic treatments, including CRISPR-Cas systems, present alternative approaches to combat resistance. Overall, this review underscores the importance of multifaceted strategies and coordinated global efforts to address antimicrobial resistance effectively.
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Affiliation(s)
- Gagandeep Singh
- Department of Biosciences (UIBT), Chandigarh University, Punjab, 140413, India
| | - Anita Rana
- Department of Biosciences (UIBT), Chandigarh University, Punjab, 140413, India.
| | - Smriti
- Department of Biosciences (UIBT), Chandigarh University, Punjab, 140413, India
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Freeman CD, Hansen T, Urbauer R, Wilkinson BJ, Singh VK, Hines KM. Defective pgsA contributes to increased membrane fluidity and cell wall thickening in Staphylococcus aureus with high-level daptomycin resistance. mSphere 2024:e0011524. [PMID: 38752757 DOI: 10.1128/msphere.00115-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 04/17/2024] [Indexed: 05/28/2024] Open
Abstract
Daptomycin is a membrane-targeting last-resort antimicrobial therapeutic for the treatment of infections caused by methicillin- and/or vancomycin-resistant Staphylococcus aureus. In the rare event of failed daptomycin therapy, the source of resistance is often attributable to mutations directly within the membrane phospholipid biosynthetic pathway of S. aureus or in the regulatory systems that control cell envelope response and membrane homeostasis. Here we describe the structural changes to the cell envelope in a daptomycin-resistant isolate of S. aureus strain N315 that has acquired mutations in the genes most commonly reported associated with daptomycin resistance: mprF, yycG, and pgsA. In addition to the decreased phosphatidylglycerol (PG) levels that are the hallmark of daptomycin resistance, the mutant with high-level daptomycin resistance had increased branched-chain fatty acids (BCFAs) in its membrane lipids, increased membrane fluidity, and increased cell wall thickness. However, the successful utilization of isotope-labeled straight-chain fatty acids (SCFAs) in lipid synthesis suggested that the aberrant BCFA:SCFA ratio arose from upstream alteration in fatty acid synthesis rather than a structural preference in PgsA. Transcriptomics studies revealed that expression of pyruvate dehydrogenase (pdhB) was suppressed in the daptomycin-resistant isolate, which is known to increase BCFA levels. While complementation with an additional copy of pdhB had no effect, complementation of the pgsA mutation resulted in increased PG formation, reduction in cell wall thickness, restoration of normal BCFA levels, and increased daptomycin susceptibility. Collectively, these results demonstrate that pgsA contributes to daptomycin resistance through its influence on membrane fluidity and cell wall thickness, in addition to phosphatidylglycerol levels. IMPORTANCE The cationic lipopeptide antimicrobial daptomycin has become an essential tool for combating infections with Staphylococcus aureus that display reduced susceptibility to β-lactams or vancomycin. Since daptomycin's activity is based on interaction with the negatively charged membrane of S. aureus, routes to daptomycin-resistance occur through mutations in the lipid biosynthetic pathway surrounding phosphatidylglycerols and the regulatory systems that control cell envelope homeostasis. Therefore, there are many avenues to achieve daptomycin resistance and several different, and sometimes contradictory, phenotypes of daptomycin-resistant S. aureus, including both increased and decreased cell wall thickness and membrane fluidity. This study is significant because it demonstrates the unexpected influence of a lipid biosynthesis gene, pgsA, on membrane fluidity and cell wall thickness in S. aureus with high-level daptomycin resistance.
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Affiliation(s)
| | - Tayte Hansen
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, USA
| | - Ramona Urbauer
- Department of Chemistry, University of Georgia, Athens, Georgia, USA
| | - Brian J Wilkinson
- School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Vineet K Singh
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, USA
| | - Kelly M Hines
- Department of Chemistry, University of Georgia, Athens, Georgia, USA
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Freeman CD, Hansen T, Urbauer R, Wilkinson BJ, Singh VK, Hines KM. Defective pgsA contributes to increased membrane fluidity and cell wall thickening in S. aureus with high-level daptomycin resistance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.04.11.536441. [PMID: 37090586 PMCID: PMC10120677 DOI: 10.1101/2023.04.11.536441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Daptomycin is a membrane-targeting last-resort antimicrobial therapeutic for the treatment of infections caused by methicillin- and/or vancomycin-resistant Staphylococcus aureus. In the rare event of failed daptomycin therapy, the source of resistance is often attributable to mutations directly within the membrane phospholipid biosynthetic pathway of S. aureus or in the regulatory systems that control cell envelope response and membrane homeostasis. Here we describe the structural changes to the cell envelope in a daptomycin-resistant isolate of S. aureus strain N315 that has acquired mutations in the genes most commonly reported associated with daptomycin-resistance: mprF, yycG, and pgsA. In addition to the decreased phosphatidylglycerol (PG) levels that are the hallmark of daptomycin-resistance, the mutant with high-level daptomycin resistance had increased branched-chain fatty acids (BCFAs) in its membrane lipids, increased membrane fluidity, and increased cell wall thickness. However, the successful utilization of isotope-labeled straight-chain fatty acids (SCFAs) in lipid synthesis suggested that the aberrant BCFA:SCFA ratio arose from upstream alteration in fatty acid synthesis rather than a structural preference in PgsA. RT-qPCR studies revealed that expression of pyruvate dehydrogenase (pdhB) was suppressed in the daptomycin-resistant isolate, which is known to increase BCFA levels. While complementation with an additional copy of pdhB had no effect, complementation of the pgsA mutation resulted in increased PG formation, reduction in cell wall thickness, restoration of normal BCFA levels, and increased daptomycin susceptibility. Collectively, these results demonstrate that pgsA contributes to daptomycin resistance through its influence on membrane fluidity and cell wall thickness, in addition to phosphatidylglycerol levels.
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Affiliation(s)
| | - Tayte Hansen
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, MO, USA
| | - Ramona Urbauer
- Department of Chemistry, University of Georgia, Athens, GA, USA
| | - Brian J. Wilkinson
- School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - Vineet K. Singh
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, MO, USA
| | - Kelly M. Hines
- Department of Chemistry, University of Georgia, Athens, GA, USA
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Gangar T, Patra S. Antibiotic persistence and its impact on the environment. 3 Biotech 2023; 13:401. [PMID: 37982084 PMCID: PMC10654327 DOI: 10.1007/s13205-023-03806-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 10/10/2023] [Indexed: 11/21/2023] Open
Abstract
From boon molecules to molecules contributing to rising concern has been the sojourn of antibiotics. The problem of antibiotic contamination has gotten worse due to antibiotics' pervasive use in every aspect of the environment. One such consequence of pollution is the increase in infections with antibiotic resistance. All known antimicrobials being used for human benefit lead to their repetitive and routine release into the environment. The misuse of antibiotics has aggravated the situation to a level that we are short of antibiotics to treat infections as organisms have developed resistance against them. Overconsumption is not just limited to human health care, but also occurs in other areas such as aquaculture, livestock, and veterinary applications for the purpose of improving feed and meat products. Due to their harmful effects on non-target species, the trace level of antibiotics in the aquatic ecosystem presents a significant problem. Since the introduction of antibiotics into the environment is more than their removal, they have been given the status of persistent pollutants. The buildup of antibiotics in the environment threatens aquatic life and may lead to bacterial strains developing resistance. As newer organisms are becoming resistant, there exists a shortage of antibiotics to treat infections. This has presented a very critical problem for the health-care community. Another rising concern is that the development of newer drug molecules as antibiotics is minimal. This review article critically explains the cause and nature of the pollution and the effects of this emerging trend. Also, in the latter sections, why we need newer antibiotics is questioned and discussed.
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Affiliation(s)
- Tarun Gangar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, North Guwahati, Assam 781039 India
| | - Sanjukta Patra
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, North Guwahati, Assam 781039 India
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Kebriaei R, Abdul-Mutakabbir JC, Stamper KC, Lev KL, Rybak MJ. Targeting Dalbavancin Inoculum Effect: Adjunctive Single Dose of Daptomycin. Infect Dis Ther 2023; 12:2485-2494. [PMID: 37798469 PMCID: PMC10600059 DOI: 10.1007/s40121-023-00875-1] [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: 08/11/2023] [Accepted: 09/14/2023] [Indexed: 10/07/2023] Open
Abstract
INTRODUCTION Daptomycin (DAP) has proven to be a viable alternative amid vancomycin resistance; however, the use of DAP post vancomycin treatment has led to the development of DAP non-susceptible (DNS) strains. Dalbavancin (DAL), a novel single-dosed lipoglycopeptide, has shown enhanced activity against highly resistant Staphylococcus aureus strains. However, on the basis of previous reports and our observations, DAL does not demonstrate similar activity at high versus low inoculum levels. Therefore, we hypothesized that addition of DAP even at minimal concentrations (single dose on day 1) will lower the inoculum to the level that can be cleared by dalbavancin. METHODS Isolates from methicillin-resistant S. aureus (MRSA)-infected patients with varying susceptibility profiles were evaluated using broth microdilution methods. Two DNS-VISA strains (vancomycin intermediate resistant S. aureus) and one MRSA strain were further evaluated in a one-compartment PK/PD model using a high starting initial inoculum of 109 CFU/mL as well as low initial inoculum of 107 CFU/mL over 168 h to assess the activity of DAL and DAP monotherapy and in combination. RESULTS Single therapies were not bactericidal when evaluated in the 168 h in vitro one-compartment model with an initial inoculum of 109; however, the combination of DAL plus single dose of DAP resulted in enhanced killing at the end of the 168-h exposure. DAL single therapy caused reduction in colony counts down to detection limit (2 log10 CFU/ml) at a lower inoculum but did not show enhancement (< 2 log10 CFU/ml) at higher initial inoculums (P < 0.01) for all three strains. Similarly, DAP caused initial bacterial reduction up to 4 log10 CFU/ml with regrowth at about 32 h of exposure, which stayed at initial inoculum levels for the duration of the model for all three strains. CONCLUSIONS Dalbavancin inoculum effect is a major issue in bacterial infections with high bacterial loads and the combination of DAL plus single dose of DAP showed promise in eradicating resistant S. aureus strains at high inoculums.
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Affiliation(s)
- Razieh Kebriaei
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
- P3 Research Laboratory, Division of Outcomes and Translational Sciences, College of Pharmacy, Ohio State University, Columbus, USA
| | - Jacinda C Abdul-Mutakabbir
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
- Division of Clinical Pharmacy, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, San Diego, CA, USA
| | - Kyle C Stamper
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
- Prism Labs, LLC, Walled Lake, MI, USA
| | - Katherine L Lev
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI, USA
| | - Michael J Rybak
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA.
- Division of Infectious Diseases, School of Medicine, Wayne State University, Detroit, MI, USA.
- Detroit Receiving Hospital, Detroit, MI, USA.
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Ide N, Kawada-Matsuo M, Le MNT, Hisatsune J, Nishi H, Hara T, Kitamura N, Kashiyama S, Yokozaki M, Kawaguchi H, Ohge H, Sugai M, Komatsuzawa H. Different CprABC amino acid sequences affect nisin A susceptibility in Clostridioides difficile isolates. PLoS One 2023; 18:e0280676. [PMID: 36662820 PMCID: PMC9858009 DOI: 10.1371/journal.pone.0280676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 01/05/2023] [Indexed: 01/21/2023] Open
Abstract
Clinical isolates of Clostridioides difficile sometimes exhibit multidrug resistance and cause diarrhea after antibiotic administration. Metronidazole and vancomycin are often used as therapeutic agents, but resistance to these antibiotics has been found clinically. Therefore, the development of alternative antimicrobial agents is needed. Nisin A, produced by Lactococcus lactis, has been demonstrated to be effective against C. difficile infection. In this study, we evaluated the susceptibility of 11 C. difficile clinical isolates to nisin A and found that they could be divided into 2 groups: high and low susceptibility. Since CprABC and DltDABC, which are responsible for nisin A efflux and cell surface charge, respectively, have been reported to be related to nisin A susceptibility, we investigated the expression of cprA and dltA among the 11 strains. cprA expression in all strains was induced by nisin A, but dltA expression was not. The expression levels of both genes did not correlate with nisin A susceptibility in these clinical isolates. To evaluate cell surface charge, we performed a cytochrome C binding assay and found no relationship between charge and nisin A susceptibility. Then, we determined the whole genome sequence of each clinical isolate and carried out phylogenetic analysis. The 11 isolates separated into two major clusters, which were consistent with the differences in nisin A susceptibility. Furthermore, we found common differences in several amino acids in the sequences of CprA, CprB, and CprC between the two clusters. Therefore, we speculated that the different amino acid sequences of CprABC might be related to nisin A susceptibility. In addition, C. difficile strains could be divided in the same two groups based on susceptibility to epidermin and mutacin III, which are structurally similar to nisin A. These results suggest that genotypic variations in C. difficile strains confer different susceptibilities to bacteriocins.
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Affiliation(s)
- Noriaki Ide
- Department of General Dentistry, Hiroshima University Hospital, Hiroshima, Japan
| | - Miki Kawada-Matsuo
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
- Project Research Center for Nosocomial Infectious Diseases, Hiroshima University, Hiroshima, Japan
| | - Mi Nguyen-Tra Le
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
- Project Research Center for Nosocomial Infectious Diseases, Hiroshima University, Hiroshima, Japan
| | - Junzo Hisatsune
- Project Research Center for Nosocomial Infectious Diseases, Hiroshima University, Hiroshima, Japan
- Antimicrobial Resistance Research Centre, National Institute of Infectious Diseases, Higashi Murayama, Japan
| | - Hiromi Nishi
- Department of General Dentistry, Hiroshima University Hospital, Hiroshima, Japan
| | - Toshinori Hara
- Antimicrobial Resistance Research Centre, National Institute of Infectious Diseases, Higashi Murayama, Japan
- Section of Clinical Laboratory, Division of Clinical Support, Hiroshima University Hospital, Hiroshima, Japan
- Division of Laboratory Medicine, Hiroshima University Hospital, Hiroshima, Japan
| | - Norikazu Kitamura
- Antimicrobial Resistance Research Centre, National Institute of Infectious Diseases, Higashi Murayama, Japan
| | - Seiya Kashiyama
- Antimicrobial Resistance Research Centre, National Institute of Infectious Diseases, Higashi Murayama, Japan
- Section of Clinical Laboratory, Division of Clinical Support, Hiroshima University Hospital, Hiroshima, Japan
- Division of Laboratory Medicine, Hiroshima University Hospital, Hiroshima, Japan
| | - Michiya Yokozaki
- Antimicrobial Resistance Research Centre, National Institute of Infectious Diseases, Higashi Murayama, Japan
- Division of Laboratory Medicine, Hiroshima University Hospital, Hiroshima, Japan
| | - Hiroyuki Kawaguchi
- Department of General Dentistry, Hiroshima University Hospital, Hiroshima, Japan
| | - Hiroki Ohge
- Antimicrobial Resistance Research Centre, National Institute of Infectious Diseases, Higashi Murayama, Japan
- Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, Japan
| | - Motoyuki Sugai
- Project Research Center for Nosocomial Infectious Diseases, Hiroshima University, Hiroshima, Japan
- Antimicrobial Resistance Research Centre, National Institute of Infectious Diseases, Higashi Murayama, Japan
| | - Hitoshi Komatsuzawa
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
- Project Research Center for Nosocomial Infectious Diseases, Hiroshima University, Hiroshima, Japan
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Modi SK, Gaur S, Sengupta M, Singh MS. Mechanistic insights into nanoparticle surface-bacterial membrane interactions in overcoming antibiotic resistance. Front Microbiol 2023; 14:1135579. [PMID: 37152753 PMCID: PMC10160668 DOI: 10.3389/fmicb.2023.1135579] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 03/30/2023] [Indexed: 05/09/2023] Open
Abstract
Antimicrobial Resistance (AMR) raises a serious concern as it contributes to the global mortality by 5 million deaths per year. The overall impact pertaining to significant membrane changes, through broad spectrum drugs have rendered the bacteria resistant over the years. The economic expenditure due to increasing drug resistance poses a global burden on healthcare community and must be dealt with immediate effect. Nanoparticles (NP) have demonstrated inherent therapeutic potential or can serve as nanocarriers of antibiotics against multidrug resistant (MDR) pathogens. These carriers can mask the antibiotics and help evade the resistance mechanism of the bacteria. The targeted delivery can be fine-tuned through surface functionalization of Nanocarriers using aptamers, antibodies etc. This review covers various molecular mechanisms acquired by resistant bacteria towards membrane modification. Mechanistic insight on 'NP surface-bacterial membrane' interactions are crucial in deciding the role of NP as therapeutic. Finally, we highlight the potential accessible membrane targets for designing smart surface-functionalized nanocarriers which can act as bacteria-targeted robots over the existing clinically available antibiotics. As the bacterial strains around us continue to evolve into resistant versions, nanomedicine can offer promising and alternative tools in overcoming AMR.
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Affiliation(s)
- Suraj Kumar Modi
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
- Centre of Excellence for Nanosensors and Nanomedicine, Bennett University, Greater Noida, Uttar Pradesh, India
| | - Smriti Gaur
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
| | - Mrittika Sengupta
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
- Centre of Excellence for Nanosensors and Nanomedicine, Bennett University, Greater Noida, Uttar Pradesh, India
- Mrittika Sengupta, ;
| | - Manu Smriti Singh
- Department of Biotechnology, Bennett University, Greater Noida, Uttar Pradesh, India
- Centre of Excellence for Nanosensors and Nanomedicine, Bennett University, Greater Noida, Uttar Pradesh, India
- *Correspondence: Manu Smriti Singh, ;
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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: 66] [Impact Index Per Article: 33.0] [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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Colistin Resistance Onset Strategies and Genomic Mosaicism in Clinical Acinetobacter baumannii Lineages. Pathogens 2021; 10:pathogens10111516. [PMID: 34832671 PMCID: PMC8623500 DOI: 10.3390/pathogens10111516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 11/16/2022] Open
Abstract
The treatment of multidrug-resistant Gram-negative infections is based on colistin. As result, COL-resistance (COL-R) can develop and spread. In Acinetobacter baumannii, a crucial step is to understand COL-R onset and stability, still far to be elucidated. COL-R phenotypic stability, onset modalities, and phylogenomics were investigated in a clinical A. baumannii sample showing a COL resistant (COLR) phenotype at first isolation. COL-R was confirmed by Minimum-Inhibitory-Concentrations as well as investigated by Resistance-Induction assays and Population-Analysis-Profiles (PAPs) to determine: (i) stability; (ii) inducibility; (iii) heteroresistance. Genomics was performed by Mi-Seq Whole-Genome-Sequencing, Phylogenesis, and Genomic Epidemiology by bioinformatics. COLRA. baumannii were subdivided as follows: (i) 3 A. baumannii with stable and high COL MICs defining the “homogeneous-resistant” onset phenotype; (ii) 6 A. baumannii with variable and lower COL MICs displaying a “COL-inducible” onset phenotype responsible for adaptive-resistance or a “subpopulation” onset phenotype responsible for COL-heteroresistance. COL-R stability and onset strategies were not uniquely linked to the amount of LPS and cell envelope charge. Phylogenomics categorized 3 lineages clustering stable and/or unstable COL-R phenotypes with increasing genomic complexity. Likewise, different nsSNP profiling in genes already associated with COL-R marked the stable and/or unstable COL-R phenotypes. Our investigation finds out that A. baumannii can range through unstable or stable COLR phenotypes emerging via different “onset strategies” within phylogenetic lineages displaying increasing genomic mosaicism.
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Cheung AL, Cho J, Bayer AS, Yeaman MR, Xiong YQ, Donegan NP, Mikheyeva IV, Lee GY, Yang SJ. Role of the Staphylococcus aureus Extracellular Loop of GraS in Resistance to Distinct Human Defense Peptides in PMN and Invasive Cardiovascular infections. Infect Immun 2021; 89:e0034721. [PMID: 34227840 PMCID: PMC8445198 DOI: 10.1128/iai.00347-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 11/20/2022] Open
Abstract
GraS is a membrane sensor in Staphylococcus aureus that induces mprF and dltABCD expression to alter the surface positive charge upon exposure to cationic human defense peptides (HDPs). The sensing domain of GraS likely resides in the 9-residue extracellular loop (EL). In this study, we assessed a hospital-acquired methicillin-resistant S. aureus (HA-MRSA) strain (COL) for the specific role of two distinct EL mutations: F38G (bulk) and D/35/37/41K (charged inversion). Activation of mprF by polymyxin B (PMB) was reduced in the D35/37/41K mutant versus the D35/37/41G mutant, correlating with reduced surface positive charge; in contrast, these effects were less prominent in the F38G mutant but still lower than those in the parent. These data indicated that both electrostatic charge and steric bulk of the EL of GraS influence induction of genes impacting HDP resistance. Using mprF expression as a readout, we confirmed GraS signaling was pH dependent, increasing as pH was lowered (from pH 7.5 down to pH 5.5). In contrast to PMB activation, reduction of mprF was comparable at pH 5.5 between the P38G and D35/37/41K point mutants, indicating a mechanistic divergence between GraS activation by acidic pH versus cationic peptides. Survival assays in human blood and purified polymorphonuclear leukocytes (PMNs) revealed lower survival of the D35/37/41K mutant versus the F38G mutant, with both being lower than that of the parent. Virulence studies in the rabbit endocarditis model mirrored whole blood and PMN killing assay data described above. Collectively, these data confirmed the importance of specific residues within the EL of GraS in conferring essential bacterial responses for MRSA survival in infections.
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Affiliation(s)
- Ambrose L. Cheung
- Department of Microbiology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Junho Cho
- Department of Microbiology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Arnold S. Bayer
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA
- The David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Michael R. Yeaman
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA
- The David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- Department of Medicine, Division of Molecular Medicine, Harbor-UCLA Medical Center, Torrance, California, USA
| | - Yan Q. Xiong
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- Department of Medicine, Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, USA
- The David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Niles P. Donegan
- Department of Microbiology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Irina V. Mikheyeva
- Department of Microbiology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Gi Yong Lee
- Department of Veterinary Microbiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
| | - Soo-Jin Yang
- Department of Veterinary Microbiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
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β-Lactam-Induced Cell Envelope Adaptations, Not Solely Enhanced Daptomycin Binding, Underlie Daptomycin-β-Lactam Synergy in Methicillin-Resistant Staphylococcus aureus. Antimicrob Agents Chemother 2021; 65:e0035621. [PMID: 34097478 DOI: 10.1128/aac.00356-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a serious clinical threat due to innate virulence properties, high infection rates, and the ability to develop resistance to multiple antibiotics, including the lipopeptide daptomycin (DAP). The acquisition of DAP resistance (DAP-R) in MRSA has been linked with several characteristic alterations in the cell envelope. Clinical treatment of DAP-R MRSA infections has generally involved DAP-plus-β-lactam combinations, although definable synergy of such combinations varies in a strain-dependent as well as a β-lactam-dependent manner. We investigated distinct β-lactam-induced cell envelope adaptations of nine clinically derived DAP-susceptible (DAP-S)/DAP-R strain pairs following in vitro exposure to a panel of six standard β-lactams (nafcillin, meropenem, cloxacillin, ceftriaxone, cefaclor, or cefoxitin), which differ in their penicillin-binding protein (PBP)-targeting profiles. In general, in both DAP-S and DAP-R strains, exposure to these β-lactams led to (i) a decreased positive surface charge; (ii) decreased cell membrane (CM) fluidity; (iii) increased content and delocalization of anionic phospholipids (i.e., cardiolipin), with delocalization being more pronounced in DAP-R strains; and (iv) increased DAP binding in DAP-S (but not DAP-R) strains. Collectively, these results suggest that β-lactam-induced alterations in at least three major cell envelope phenotypes (surface charge, membrane fluidity, and cardiolipin content) could underlie improved DAP activity, not mediated solely by an increase in DAP binding. (Note that for ease of presentation, we utilize the terminology "DAP-R" instead of "DAP nonsusceptibility.").
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Shen T, Hines KM, Ashford NK, Werth BJ, Xu L. Varied Contribution of Phospholipid Shedding From Membrane to Daptomycin Tolerance in Staphylococcus aureus. Front Mol Biosci 2021; 8:679949. [PMID: 34179085 PMCID: PMC8226217 DOI: 10.3389/fmolb.2021.679949] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/24/2021] [Indexed: 11/16/2022] Open
Abstract
It has been suggested that daptomycin can be inactivated by lipids released by Staphylococcus aureus and that this effect is antagonized by phenol soluble modulins (PSMs), which bind to the shed lipids. PSM production is regulated by the Agr system, and others have shown that loss of the Agr function enhances S. aureus survival in the presence of daptomycin. Here we assessed the impact of Agr function on daptomycin activity and lipid metabolism under various conditions. Daptomycin activity was evaluated against three sets of isogenic strain series with wild-type or dysfunctional Agr using static daptomycin time-kills over 24 h and against one strain pair using in vitro pharmacokinetic/pharmacodynamic (PK/PD) models simulating clinical daptomycin exposure for 48 h. We performed comprehensive lipidomics on bacterial membranes and the spent media to correlate lipid shedding with survival. In static time-kill experiments, two agr-deficient strains (SH1000- and USA300 LAC ΔagrA) showed improved survival for 8 h compared with their corresponding wild-type strains as seen in previous studies, but this difference did not persist for 24 h. However, four other agr-deficient strains (SH1001 and JE2 agr KOs) did not demonstrate improved survival compared to isogenic wild-type strains at any time in the time-kills. Lipidomics analysis of SH1000, SH1001, and SH1000- strains showed daptomycin exposure increased lipid shedding compared to growth controls in all strains with phosphatidylglycerols (PGs), lysylPGs and cardiolipins predominating. In the cell pellets, PGs and lysylPGs decreased but cardiolipins were unchanged with daptomycin exposure. The shed lipid profiles in SH1001 and SH1000- were similar, suggesting that the inability to resist daptomycin by SH1001 was not because of differences in lipid shedding. In the PK/PD model, the agr mutant SH1000- strain did not show improved survival relative to SH1000 either. In conclusion, inactivation of daptomycin by shed lipids may be dependent on genetic background, the specific agr mutations, or the techniques used to generate these KOs rather than the overall function of the Agr system, and its contribution to daptomycin tolerance seems to be varied, transient, and growth-condition dependent.
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Affiliation(s)
- Tianwei Shen
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, WA, United States
| | - Kelly M. Hines
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, WA, United States
| | - Nathaniel K. Ashford
- Department of Pharmacy, School of Pharmacy, University of Washington, Seattle, WA, United States
| | - Brian J. Werth
- Department of Pharmacy, School of Pharmacy, University of Washington, Seattle, WA, United States
| | - Libin Xu
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, WA, United States
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Cho J, Costa SK, Wierzbicki RM, Rigby WFC, Cheung AL. The extracellular loop of the membrane permease VraG interacts with GraS to sense cationic antimicrobial peptides in Staphylococcus aureus. PLoS Pathog 2021; 17:e1009338. [PMID: 33647048 PMCID: PMC7951975 DOI: 10.1371/journal.ppat.1009338] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 03/11/2021] [Accepted: 01/27/2021] [Indexed: 01/27/2023] Open
Abstract
Host defense proteins (HDPs), aka defensins, are a key part of the innate immune system that functions by inserting into the bacterial membranes to form pores to kill invading and colonizing microorganisms. To ensure survival, microorganism such as S. aureus has developed survival strategies to sense and respond to HDPs. One key strategy in S. aureus is a two-component system (TCS) called GraRS coupled to an efflux pump that consists of a membrane permease VraG and an ATPase VraF, analogous to the BceRS-BceAB system of Bacillus subtilis but with distinct differences. While the 9 negatively charged amino acid extracellular loop of the membrane sensor GraS has been shown to be involved in sensing, the major question is how such a small loop can sense diverse HDPs. Mutation analysis in this study divulged that the vraG mutant phenocopied the graS mutant with respect to reduced activation of downstream effector mprF, reduction in surface positive charge and enhanced 2 hr. killing with LL-37 as compared with the parental MRSA strain JE2. In silico analysis revealed VraG contains a single 200-residue extracellular loop (EL) situated between the 7th and 8th transmembrane segments (out of 10). Remarkably, deletion of EL in VraG enhanced mprF expression, augmented surface positive charge and improved survival in LL-37 vs. parent JE2. As the EL of VraG is rich in lysine residues (16%), in contrast to a preponderance of negatively charged aspartic acid residues (3 out of 9) in the EL of GraS, we divulged the role of charge interaction by showing that K380 in the EL of VraG is an important residue that likely interacts with GraS to interfere with GraS-mediated signaling. Bacterial two-hybrid analysis also supported the interaction of EL of VraG with the EL of GraS. Collectively, we demonstrated an interesting facet of efflux pumps whereby the membrane permease disrupts HDP signaling by inhibiting GraS sensing that involves charged residues in the EL of VraG.
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Affiliation(s)
- Junho Cho
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, United States of America
| | - Stephen K. Costa
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, United States of America
| | - Rachel M. Wierzbicki
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, United States of America
- Department of Medicine, Geisel School of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, United States of America
| | - William F. C. Rigby
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, United States of America
- Department of Medicine, Geisel School of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, United States of America
| | - Ambrose L. Cheung
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, United States of America
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Wu X, Han J, Gong G, Koffas MAG, Zha J. Wall teichoic acids: physiology and applications. FEMS Microbiol Rev 2020; 45:6019871. [DOI: 10.1093/femsre/fuaa064] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 12/01/2020] [Indexed: 12/21/2022] Open
Abstract
ABSTRACT
Wall teichoic acids (WTAs) are charged glycopolymers containing phosphodiester-linked polyol units and represent one of the major components of Gram-positive cell envelope. WTAs have important physiological functions in cell division, gene transfer, surface adhesion, drug resistance and biofilm formation, and are critical virulence factors and vital determinants in mediating cell interaction with and tolerance to environmental factors. Here, we first briefly introduce WTA structure, biosynthesis and its regulation, and then summarize in detail four major physiological roles played by WTAs, i.e. WTA-mediated resistance to antimicrobials, virulence to mammalian cells, interaction with bacteriolytic enzymes and regulation of cell metabolism. We also review the applications of WTAs in these fields that are closely related to the human society, including antibacterial drug discovery targeting WTA biosynthesis, development of vaccines and antibodies regarding WTA-mediated pathogenicity, specific and sensitive detection of pathogens in food using WTAs as a surface epitope and regulation of WTA-related pathways for efficient microbial production of useful compounds. We also point out major problems remaining in these fields, and discuss some possible directions in the future exploration of WTA physiology and applications.
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Affiliation(s)
- Xia Wu
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Jing Han
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Guoli Gong
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Mattheos A G Koffas
- Center for Biotechnology and Interdisciplinary Studies, Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Jian Zha
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
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Genetic Factors Associated with Increased Host Defense Antimicrobial Peptide Resistance in Sequence Type 5 Healthcare-Associated MRSA Clinical Isolates. Biomolecules 2020; 10:biom10101415. [PMID: 33036325 PMCID: PMC7599770 DOI: 10.3390/biom10101415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 09/28/2020] [Accepted: 10/06/2020] [Indexed: 11/23/2022] Open
Abstract
Sequence type (ST) 72 methicillin-resistant Staphylococcus aureus with staphylococcal cassette chromosome mec (SCCmec) type IV (ST72-MRSA-IV) and ST5-MRSA-II are the most significant lineages found in community-associated (CA) and healthcare-associated (HA) environments in Korea, respectively. ST5 HA-MRSA-II tend to display enhanced resistance to host defense-cationic antimicrobial peptides (HD-CAPs) compared to ST72 CA-MRSA-IV and ST72 livestock-associated (LA)-MRSA-IV due to mechanisms involving a higher surface positive charge. Thus, the present study explored the genetic factors contributing to the enhanced HD-CAP resistance phenotype in ST5 MRSA strains. The ST5 HA-MRSA-II strains displayed higher levels of mprF and dltABCD expression compared to the ST72 CA-/LA-MRSA-IV strains. The increase in expression of mprF and dltABCD in ST5 HA-MRSA-II strains was correlated with dysregulation of the upstream transcriptional regulator, graRS. However, single nucleotide polymorphisms (SNPs) within mprF and graRS ORFs were not involved in the enhanced surface positive charge or the altered expression of mprF/dltABCD.
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Cafiso V, Stracquadanio S, Lo Verde F, De Guidi I, Zega A, Pigola G, Stefani S. Genomic and Long-Term Transcriptomic Imprints Related to the Daptomycin Mechanism of Action Occurring in Daptomycin- and Methicillin-Resistant Staphylococcus aureus Under Daptomycin Exposure. Front Microbiol 2020; 11:1893. [PMID: 32922373 PMCID: PMC7456847 DOI: 10.3389/fmicb.2020.01893] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 07/20/2020] [Indexed: 01/06/2023] Open
Abstract
Daptomycin (DAP) is one of the last-resort treatments for heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) and vancomycin-intermediate S. aureus (VISA) infections. DAP resistance (DAP-R) is multifactorial and mainly related to cell-envelope modifications caused by single-nucleotide polymorphisms and/or modulation mechanisms of transcription emerging as result of a self-defense process in response to DAP exposure. Nevertheless, the role of these adaptations remains unclear. We aim to investigate the comparative genomics and late post-exponential growth-phase transcriptomics of two DAP-resistant/DAP-susceptible (DAPR/S) methicillin-resistant S. aureus (MRSA) clinical strain pairs to focalize the genomic and long-term transcriptomic fingerprinting and adaptations related to the DAP mechanism of action acquired in vivo under DAP pressure using Illumina whole-genome sequencing (WGS), RNA-seq, bioinformatics, and real-time qPCR validation. Comparative genomics revealed that membrane protein and transcriptional regulator coding genes emerged as shared functional coding-gene clusters harboring mutational events related to the DAP-R onset in a strain-dependent manner. Pairwise transcriptomic enrichment analysis highlighted common and strain pair-dependent Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, whereas DAPR/S double-pair cross-filtering returned 53 differentially expressed genes (DEGs). A multifactorial long-term transcriptomic-network characterized DAPR MRSA includes alterations in (i) peptidoglycan biosynthesis, cell division, and cell-membrane (CM) organization genes, as well as a cidB/lytS autolysin genes; (ii) ldh2 involved in fermentative metabolism; (iii) CM-potential perturbation genes; and (iv) oxidative and heat/cold stress response-related genes. Moreover, a D-alanyl–D-alanine decrease in cell-wall muropeptide characterized DAP/glycopeptide cross-reduced susceptibility mechanisms in DAPR MRSA. Our data provide a snapshot of DAPR MRSA genomic and long-term transcriptome signatures related to the DAP mechanism of action (MOA) evidencing that a complex network of genomic changes and transcriptomic adaptations is required to acquire DAP-R.
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Affiliation(s)
- Viviana Cafiso
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Stefano Stracquadanio
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Flavia Lo Verde
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Irene De Guidi
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Alessandra Zega
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Giuseppe Pigola
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
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17
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Reed JM, Gardner SG, Mishra NN, Bayer AS, Somerville GA. Metabolic interventions for the prevention and treatment of daptomycin non-susceptibility in Staphylococcus aureus. J Antimicrob Chemother 2020; 74:2274-2283. [PMID: 31074482 DOI: 10.1093/jac/dkz194] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 04/03/2019] [Accepted: 04/07/2019] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND A major developing problem in the treatment of Staphylococcus aureus infections is the emergence of resistance during treatment with daptomycin. Previous metabolomic analyses of isogenic S. aureus strains prior to and after evolution into a daptomycin non-susceptible (DapNS) state provided important metabolic information about this transition (e.g. perturbations of the tricarboxylic acid cycle). OBJECTIVES To assess the significance of these metabolic changes, in vitro susceptibility to daptomycin was determined in daptomycin-susceptible (DapS) and DapNSS. aureus strains cultivated with metabolic inhibitors targeting these changes. METHODS Only inhibitors that are approved for use in humans were chosen (i.e. fosfomycin, valproate, trimetazidine and 6-mercaptopurine) to assess the importance of metabolic pathways for daptomycin non-susceptibility. The ability of these inhibitors to forestall the emergence of DapNS strains was also assessed. RESULTS The combination of daptomycin and fosfomycin synergistically killed both DapS and DapNS strains in vitro and enhanced the in vivo outcome against a DapNS strain in experimental endocarditis. Interestingly, fosfomycin acts on the peptidoglycan biosynthetic enzyme UDP-N-acetylglucosamine enolpyruvyl transferase (MurA); however, it also had a significant effect on the enzymatic activity of enolase, an essential enzyme in S. aureus. While fosfomycin acted synergistically with daptomycin, it failed to prevent the in vitro evolution of daptomycin non-susceptibility. In contrast, trimetazidine, an anti-angina drug that stimulates glucose oxidation, abolished the ability of DapSS. aureus strains to transition to a DapNS state. CONCLUSIONS These data reveal that metabolic adaptations associated with DapNS strains can be targeted to prevent the emergence of and/or reverse pre-existing resistance to daptomycin.
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Affiliation(s)
- Joseph M Reed
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0905, USA
| | - Stewart G Gardner
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0905, USA
| | - Nagendra N Mishra
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA.,Geffen School of Medicine at UCLA, Los Angeles, CA 90024, USA
| | - Arnold S Bayer
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA.,Geffen School of Medicine at UCLA, Los Angeles, CA 90024, USA
| | - Greg A Somerville
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0905, USA
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18
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Gray DA, Wenzel M. More Than a Pore: A Current Perspective on the In Vivo Mode of Action of the Lipopeptide Antibiotic Daptomycin. Antibiotics (Basel) 2020; 9:E17. [PMID: 31947747 PMCID: PMC7168178 DOI: 10.3390/antibiotics9010017] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 12/29/2019] [Accepted: 12/31/2019] [Indexed: 12/19/2022] Open
Abstract
Daptomycin is a cyclic lipopeptide antibiotic, which was discovered in 1987 and entered the market in 2003. To date, it serves as last resort antibiotic to treat complicated skin infections, bacteremia, and right-sided endocarditis caused by Gram-positive pathogens, most prominently methicillin-resistant Staphylococcus aureus. Daptomycin was the last representative of a novel antibiotic class that was introduced to the clinic. It is also one of the few membrane-active compounds that can be applied systemically. While membrane-active antibiotics have long been limited to topical applications and were generally excluded from systemic drug development, they promise slower resistance development than many classical drugs that target single proteins. The success of daptomycin together with the emergence of more and more multi-resistant superbugs attracted renewed interest in this compound class. Studying daptomycin as a pioneering systemic membrane-active compound might help to pave the way for future membrane-targeting antibiotics. However, more than 30 years after its discovery, the exact mechanism of action of daptomycin is still debated. In particular, there is a prominent discrepancy between in vivo and in vitro studies. In this review, we discuss the current knowledge on the mechanism of daptomycin against Gram-positive bacteria and try to offer explanations for these conflicting observations.
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Affiliation(s)
- Declan Alan Gray
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
| | - Michaela Wenzel
- Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
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Ahmad A, Majaz S, Nouroz F. Two-component systems regulate ABC transporters in antimicrobial peptide production, immunity and resistance. Microbiology (Reading) 2020; 166:4-20. [DOI: 10.1099/mic.0.000823] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Bacteria offer resistance to a broad range of antibiotics by activating their export channels of ATP-binding cassette transporters. These transporters perform a central role in vital processes of self-immunity, antibiotic transport and resistance. The majority of ATP-binding cassette transporters are capable of detecting the presence of antibiotics in an external vicinity and are tightly regulated by two-component systems. The presence of an extracellular loop and an adjacent location of both the transporter and two-component system offers serious assistance to induce a quick and specific response against antibiotics. Both systems have demonstrated their ability of sensing such agents, however, the exact mechanism is not yet fully established. This review highlighted the three key functions of antibiotic resistance, transport and self-immunity of ATP-binding cassette transporters and an adjacent two-component regulatory system.
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Affiliation(s)
- Ashfaq Ahmad
- Department of Bioinformatics, Hazara University, Mansehra, KPK, Pakistan
| | - Sidra Majaz
- Department of Bioinformatics, Hazara University, Mansehra, KPK, Pakistan
| | - Faisal Nouroz
- Department of Bioinformatics, Hazara University, Mansehra, KPK, Pakistan
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Environment Shapes the Accessible Daptomycin Resistance Mechanisms in Enterococcus faecium. Antimicrob Agents Chemother 2019; 63:AAC.00790-19. [PMID: 31332078 DOI: 10.1128/aac.00790-19] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 07/16/2019] [Indexed: 02/07/2023] Open
Abstract
Daptomycin binds to bacterial cell membranes and disrupts essential cell envelope processes, leading to cell death. Bacteria respond to daptomycin by altering their cell envelopes to either decrease antibiotic binding to the membrane or by diverting binding away from septal targets. In Enterococcus faecalis, daptomycin resistance is typically coordinated by the three-component cell envelope stress response system, LiaFSR. Here, studying a clinical strain of multidrug-resistant Enterococcus faecium containing alleles associated with activation of the LiaFSR signaling pathway, we found that specific environments selected for different evolutionary trajectories, leading to high-level daptomycin resistance. Planktonic environments favored pathways that increased cell surface charge via yvcRS upregulation of dltABCD and mprF, causing a reduction in daptomycin binding. Alternatively, environments favoring complex structured communities, including biofilms, evolved both diversion and repulsion strategies via divIVA and oatA mutations, respectively. Both environments subsequently converged on cardiolipin synthase (cls) mutations, suggesting the importance of membrane modification across strategies. Our findings indicate that E. faecium can evolve diverse evolutionary trajectories to daptomycin resistance that are shaped by the environment to produce a combination of resistance strategies. The accessibility of multiple and different biochemical pathways simultaneously suggests that the outcome of daptomycin exposure results in a polymorphic population of resistant phenotypes, making E. faecium a recalcitrant nosocomial pathogen.
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Kuroda M, Sekizuka T, Matsui H, Ohsuga J, Ohshima T, Hanaki H. IS 256-Mediated Overexpression of the WalKR Two-Component System Regulon Contributes to Reduced Vancomycin Susceptibility in a Staphylococcus aureus Clinical Isolate. Front Microbiol 2019; 10:1882. [PMID: 31474962 PMCID: PMC6702299 DOI: 10.3389/fmicb.2019.01882] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 07/30/2019] [Indexed: 11/13/2022] Open
Abstract
Vancomycin (VAN)-intermediate-resistant Staphylococcus aureus (VISA) is continually isolated globally, with a systematic review suggesting a prevalence of 2% in all blood culture samples. Most VISA strains exhibit common characteristics, such as a thickened cell wall, reduced autolysis, and attenuated virulence. Here, based on multi-omics approaches, we have characterized clinical VISA isolates obtained through prolonged antimicrobial treatment in a single patient. All VISA isolates were isogenic, based on multi-locus sequence typing (MLST) ST5, SCCmec type II (2A), and spa type t17639. Core-genome single nucleotide variations (SNVs) found among thirteen isolates during the patient's hospitalization, indicated clonality, but not notable genetic features of the VISA phenotype. We determined the complete genome sequence of VAN-susceptible strain KG-03 (minimum inhibitory concentration [MIC] 0.5 μg/mL) and two VISA strains, KG-18 and KG-22 (MIC 8.0 and 4.0 μg/mL, respectively). Comparative genome analysis showed remarkable strain-specific IS256 insertions. RNA-Seq transcriptome analysis revealed IS256-mediated overexpression of the walKR two-component system in VISA KG-18, possibly leading to modulation of cell wall integrity (lytM and sceD) and surface charge (mprF and dltABCD). In addition, secretome analysis indicated that cell wall-anchored proteins (Protein A, SasG, and SdrD) were significantly decreased. KG-18 and KG-22 exhibit thickened cell wall, and are relatively resistant to lysostaphin, which cleaves a staphylococcus-unique pentaglycine chain in the peptidoglycan. We conclude that KG-18 achieved reduced susceptibility to VAN by IS256-mediated WalKR overexpression, leading to a markedly thickened cell wall for trapping free VAN molecules with redundant D-Ala-D-Ala targets. In addition, a positively charged surface with lysyl-phosphatidylglycerol and depolarization of wall teichoic acid could contribute to inhibiting cationic daptomycin and VAN antimicrobial activity. Comparative omics approaches in this study strongly suggest that fully complete and annotated genome sequences will be indispensable for characterizing overall VISA phenotype.
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Affiliation(s)
- Makoto Kuroda
- Pathogen Genomics Center, National Institute of Infectious Diseases, Shinjuku, Japan
| | - Tsuyoshi Sekizuka
- Pathogen Genomics Center, National Institute of Infectious Diseases, Shinjuku, Japan
| | - Hidehito Matsui
- Infection Control Research Center, Kitasato University, Minato-ku, Japan
| | - Jun Ohsuga
- Department of Clinical Laboratory, Tokai University Oiso Hospital, Kanagawa, Japan
| | - Toshio Ohshima
- Department of Medical Risk and Crisis Management, Chiba Institute of Science, Chiba, Japan
| | - Hideaki Hanaki
- Infection Control Research Center, Kitasato University, Minato-ku, Japan
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Lasek-Nesselquist E, Lu J, Schneider R, Ma Z, Russo V, Mishra S, Pai MP, Pata JD, McDonough KA, Malik M. Insights Into the Evolution of Staphylococcus aureus Daptomycin Resistance From an in vitro Bioreactor Model. Front Microbiol 2019; 10:345. [PMID: 30891010 PMCID: PMC6413709 DOI: 10.3389/fmicb.2019.00345] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 02/08/2019] [Indexed: 02/02/2023] Open
Abstract
The extensive use of daptomycin for treating complex methicillin-resistant Staphylococcus aureus infections has led to the emergence of daptomycin-resistant strains. Although genomic studies have identified mutations associated with daptomycin resistance, they have not necessarily provided insight into the evolution and hierarchy of genetic changes that confer resistance, particularly as antibiotic concentrations are increased. Additionally, plate-dependent in vitro analyses that passage bacteria in the presence of antibiotics can induce selective pressures unrelated to antibiotic exposure. We established a continuous culture bioreactor model that exposes S. aureus strain N315 to increasing concentrations of daptomycin without the confounding effects of nutritional depletion to further understand the evolution of drug resistance and validate the bioreactor as a method that produces clinically relevant results. Samples were collected every 24 h for a period of 14 days and minimum inhibitory concentrations were determined to monitor the acquisition of daptomycin resistance. The collected samples were then subjected to whole genome sequencing. The development of daptomycin resistance in N315 was associated with previously identified mutations in genes coding for proteins that alter cell membrane charge and composition. Although genes involved in metabolic functions were also targets of mutation, the common route to resistance relied on a combination of mutations at a few key loci. Tracking the frequency of each mutation throughout the experiment revealed that mutations need not arise progressively in response to increasing antibiotic concentrations and that most mutations were present at low levels within populations earlier than would be recorded based on single-nucleotide polymorphism (SNP) filtering criteria. In contrast, a serial-passaged population showed only one mutation in a gene associated with resistance and provided limited detail on the changes that occur upon exposure to higher drug dosages. To conclude, this study demonstrates the successful in vitro modeling of antibiotic resistance in a bioreactor and highlights the evolutionary paths associated with the acquisition of daptomycin non-susceptibility.
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Affiliation(s)
| | - Jackson Lu
- Albany College of Pharmacy and Health Sciences, Albany, NY, United States
| | - Ryan Schneider
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, NY, United States
| | - Zhuo Ma
- Albany College of Pharmacy and Health Sciences, Albany, NY, United States
| | - Vincenzo Russo
- Albany College of Pharmacy and Health Sciences, Albany, NY, United States
| | - Smruti Mishra
- Albany College of Pharmacy and Health Sciences, Albany, NY, United States
| | - Manjunath P Pai
- Department of Clinical Pharmacy, University of Michigan, Ann Arbor, MI, United States
| | - Janice D Pata
- Wadsworth Center, New York State Department of Health, Albany, NY, United States.,Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, NY, United States
| | - Kathleen A McDonough
- Wadsworth Center, New York State Department of Health, Albany, NY, United States.,Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, NY, United States
| | - Meenakshi Malik
- Albany College of Pharmacy and Health Sciences, Albany, NY, United States
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23
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Evolution of Daptomycin Resistance in Coagulase-Negative Staphylococci Involves Mutations of the Essential Two-Component Regulator WalKR. Antimicrob Agents Chemother 2019; 63:AAC.01926-18. [PMID: 30617095 DOI: 10.1128/aac.01926-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 01/02/2019] [Indexed: 01/19/2023] Open
Abstract
Coagulase-negative staphylococci (CoNS) represent one of the major causes of health care- and medical device-associated infections. Emerging antimicrobial resistance has complicated the treatment of systemic infections caused by CoNS. Here, we describe the prevalence of antimicrobial resistance in clinical CoNS strains from a tertiary care hospital over a 4-year period, and we observed a significant increase in resistance to daptomycin. Notably, Staphylococcus capitis accounted for the majority of these daptomycin-resistant (DAP-R) CoNS. To further investigate the mechanisms of daptomycin resistance in CoNS, daptomycin-susceptible clinical strains of S. capitis and Staphylococcus epidermidis underwent in vitro daptomycin exposure to generate DAP-R CoNS mutants. Unlike that seen with Staphylococcus aureus, alteration of cell surface charge was not observed in the DAP-R CoNS strains, but biofilm formation was compromised. Whole-genome sequencing analysis of the DAP-R CoNS strains identified single nucleotide polymorphisms (SNPs) in walKR, the essential two-component regulatory system controlling cell wall biogenesis. PCR and sequencing of walK and walR from 17 DAP-R CoNS clinical isolates identified seven nonsynonymous mutations. The results were confirmed by the recreation of the walK SNP in S. epidermidis, which resulted in reduced susceptibility to daptomycin and vancomycin. This study highlights the significance of CoNS in evolving daptomycin resistance and showed that walKR is shared among the staphylococcal species and is involved in antibiotic resistance development. Notably, we did not observe mutations in genes responsible for phospholipid biosynthesis or an altered cell surface charge, suggesting that reduced daptomycin susceptibility in CoNS may emerge in a fashion distinct from that in S. aureus.
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24
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Cafiso V, Stracquadanio S, Lo Verde F, Gabriele G, Mezzatesta ML, Caio C, Pigola G, Ferro A, Stefani S. Colistin Resistant A. baumannii: Genomic and Transcriptomic Traits Acquired Under Colistin Therapy. Front Microbiol 2019; 9:3195. [PMID: 30666237 PMCID: PMC6330354 DOI: 10.3389/fmicb.2018.03195] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 12/10/2018] [Indexed: 12/31/2022] Open
Abstract
Even though colistin-based treatment represents the antimicrobial-regimen backbone for the management of multidrug-resistant Gram-negative infections, colistin resistance is still rare, at least as a full resistance, in Acinetobacter baumannii (Ab). We investigated the genomics and transcriptomics of two clinical Extensively Drug Resistance (XDR) colistin-susceptible/resistant (COL-S/R) Ab strain-pairs in which COL-resistance was developed after exposure to colistin therapy. The molecular characterization of the strains showed that all strains belonged to PFGE-A, ST-281, OXA-23 producers, Global Clone-II, and were resistant to imipenem, meropenem, ampicillin/sulbactam, ciprofloxacin, gentamicin, amikacin, trimethoprim/sulfamethoxazole, and susceptible to tigecycline, in agreement with NGS-acquired resistome. COL-R vs. COL-S Ab comparative genomics, mapping on Ab ATCC 17978 and Ab ACICU Reference Genomes, revealed a closely related genomic phylogeny, especially between strain-pair isolates, and distinctive common genomic non-synonymous SNPs (nsSNPs) in COL-R Ab strains. Furthermore, pmrB and pmrC nsSNPs were found. Notably we recovered, for the first time, lpxC and lpxD nsSNPs previously described only in "in-vitro" mutants and associated with colistin resistance in a clinical COL-R Ab. COL-R vs. COL-S Ab comparative transcriptomics evidenced a strain-dependent response to the colistin resistance onset highly variable among the single COL-R strains vs. their COL-S parents and merely seven common over-expressed transcripts, i.e. the PgaB lipoprotein for biofilm-matrix production, the diacylglycerol kinase for the lipid recycling in the membrane-derived oligosaccharide cycle, a membrane non-ribosomal peptide synthetase, the Lipid A phosphoethanol aminotransferase PmrC, and three hypothetical proteins. The transcript analysis of the "COL-R related genes" and the RNA-seq data confirmed pmrCAB over-expression responsible for a greater positive net cell-charge, and lpxACD under-expression in COL-R causing a decreased LPS production, as main mechanisms of colistin resistance. Our study reports the COL-R Ab genomic and transcriptomic signatures reflecting the interplay between several direct and indirect potential adaptations to antimicrobial pressure, including the occurrence of SNP accumulation hotspot loci in genes related to intrinsic or adaptive colistin resistance, surface adhesion proteins and porins, and over-expressed genes involved in different pathways, i.e. biofilm production, oxidative stress response, extensive drug and COL resistance.
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Affiliation(s)
- Viviana Cafiso
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Stefano Stracquadanio
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Flavia Lo Verde
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Giacoma Gabriele
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Maria Lina Mezzatesta
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Carla Caio
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Giuseppe Pigola
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Alfredo Ferro
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
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25
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Daptomycin Resistance and Tolerance Due to Loss of Function in Staphylococcus aureus dsp1 and asp23. Antimicrob Agents Chemother 2018; 63:AAC.01542-18. [PMID: 30397055 DOI: 10.1128/aac.01542-18] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/23/2018] [Indexed: 02/07/2023] Open
Abstract
Lipopeptide daptomycin is a last-line cell-membrane-targeting antibiotic to treat multidrug-resistant Staphylococcus aureus Alarmingly, daptomycin-resistant S. aureus isolates have emerged. The mechanisms underlying daptomycin resistance are diverse and share similarities with resistances to cationic antimicrobial peptides and other lipopeptides, but they remain to be fully elucidated. We selected mutants with increased resistance to daptomycin from a library of transposon insertions in sequent type 8 (ST8) S. aureus HG003. Insertions conferring increased daptomycin resistance were localized to two genes, one coding for a hypothetical lipoprotein (SAOUHSC_00362, Dsp1), and the other for an alkaline shock protein (SAOUHSC_02441, Asp23). Markerless loss-of-function mutants were then generated for comparison. All transposon mutants and knockout strains exhibited increased daptomycin resistance compared to those of wild-type and complemented strains. Null and transposon insertion mutants also exhibited increased resistance to cationic antimicrobial peptides. Interestingly, the Δdsp1 mutant also showed increased resistance to vancomycin, a cell-wall-targeting drug with a different mode of action. Null mutations in both dsp1 and asp23 resulted in increased tolerance as reflected by reduced killing to both daptomycin and vancomycin, as well as an increased tolerance to surfactant (Triton X-100). Neither mutant exhibited increased resistance to lysostaphin, a cell-wall-targeting endopeptidase. These findings identified two genes core to the S. aureus species that make previously uncharacterized contributions to antimicrobial resistance and tolerance in S. aureus.
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26
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Reygaert WC. An overview of the antimicrobial resistance mechanisms of bacteria. AIMS Microbiol 2018; 4:482-501. [PMID: 31294229 PMCID: PMC6604941 DOI: 10.3934/microbiol.2018.3.482] [Citation(s) in RCA: 568] [Impact Index Per Article: 94.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/13/2018] [Indexed: 01/29/2023] Open
Abstract
Resistance to antimicrobial agents has become a major source of morbidity and mortality worldwide. When antibiotics were first introduced in the 1900's, it was thought that we had won the war against microorganisms. It was soon discovered however, that the microorganisms were capable of developing resistance to any of the drugs that were used. Apparently most pathogenic microorganisms have the capability of developing resistance to at least some antimicrobial agents. The main mechanisms of resistance are: limiting uptake of a drug, modification of a drug target, inactivation of a drug, and active efflux of a drug. These mechanisms may be native to the microorganisms, or acquired from other microorganisms. Understanding more about these mechanisms should hopefully lead to better treatment options for infective diseases, and development of antimicrobial drugs that can withstand the microorganisms attempts to become resistant.
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Affiliation(s)
- Wanda C Reygaert
- Department of Biomedical Sciences, Oakland University William Beaumont School of Medicine, Rochester, MI, USA
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27
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Lee GY, Kang KM, Back SH, Baek JY, Kim SH, Park JH, Yang SJ. Adaptations of Vancomycin-Intermediate Sequence Type 72 Methicillin-Resistant Staphylococcus aureus for Daptomycin Nonsusceptibility. Microb Drug Resist 2018; 24:1489-1496. [PMID: 29927700 DOI: 10.1089/mdr.2018.0112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In Korea, the major clonal type of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is sequence type 72 (ST72) with staphylococcal cassette chromosome mec (SCCmec) type IV (ST72-MRSA-IV). In this study, we used a previously well-characterized isogenic pair of ST72 vancomycin (VAN) susceptible-and VAN intermediate-MRSA strains (VSSA303 and VISA072) and several VSSA strains complemented with plasmids expressing single-point mutated genes (dprAG196C, femAF92C, vraRE127K, and vraSRE127K) identified in the VISA strain. Using the strain set, we assessed the (1) susceptibilities to daptomycin (DAP) and cationic antimicrobial peptides (CAMPs), (2) alterations in cell envelope phenotypes, such as cell wall autolysis, surface positive charge, and membrane potential (ΔΨ), (3) transcriptional expression profiles of genes involved in surface charge regulation and changes of ΔΨ, and (4) cytokine stimulation profiles in murine macrophages. The vraRE127K mutation could enhance surface positive charge through mprF- and dltABCD-independent mechanisms with thickened cell wall. However, none of the single-point mutated genes increased DAP resistance. The DAP nonsusceptible (DAP-NS) phenotype observed in VISA072 strain likely resulted from the combined effects of low ΔΨ and increased positive surface charge. These results suggest that physicochemical alterations in cell envelope are involved in the survival response of DAP-NS VISA072 in sites of infections.
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Affiliation(s)
- Gi Yong Lee
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
| | - Kyung Mi Kang
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
| | - Seung Hyun Back
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
| | - Jin Yang Baek
- 2 Asia Pacific Foundation for Infectious Diseases (APFID) , Seoul, Korea
- 3 Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea
| | - So Hyun Kim
- 2 Asia Pacific Foundation for Infectious Diseases (APFID) , Seoul, Korea
- 3 Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea
| | - Jong-Hwan Park
- 4 Laboratory Animal Medicine, College of Veterinary Medicine, Chonnam National University , Gwangju, Korea
| | - Soo-Jin Yang
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
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28
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Ma Z, Lasek-Nesselquist E, Lu J, Schneider R, Shah R, Oliva G, Pata J, McDonough K, Pai MP, Rose WE, Sakoulas G, Malik M. Characterization of genetic changes associated with daptomycin nonsusceptibility in Staphylococcus aureus. PLoS One 2018; 13:e0198366. [PMID: 29879195 PMCID: PMC5991675 DOI: 10.1371/journal.pone.0198366] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 05/17/2018] [Indexed: 11/25/2022] Open
Abstract
The extensive use of daptomycin (DAP) for treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in the last decade has led to the emergence of DAP non-susceptible (DNS) Staphylococcus aureus strains. A better understanding of the molecular changes underlying DAP-non-susceptibility is required for early diagnosis and intervention with alternate combination therapies. The phenotypic changes associated with DNS strains have been well established. However, the genotypic changes—especially the kinetics of expression of the genes responsible for DAP-non-susceptibility are not well understood. In this study, we used three clinically derived isogenic pairs of DAP-susceptible (DAP-S) and DNS S. aureus strains to study gene expression profiles with the objective of identifying the potential genotypic changes associated with DAP-nonsusceptibility. We determined the expression profiles of genes involved in cell membrane (CM) charge, autolysis, cell wall (CW) synthesis, and penicillin binding proteins in DAP-S and DNS isogenic pairs. Our results demonstrate characteristic expression profiles for mprF, dltABCD, vraS, femB, and pbp2a genes, which are common to all the DNS S. aureus strains tested. Whole genome sequencing of DAP-S and DNS clinical isolates of S. aureus showed non-synonymous mutations in all DNS strains in genes involved in CM charge, CM composition, CW thickness and CW composition. To conclude, this study unravels some of the complex molecular changes involved in the development of DAP-nonsusceptibility by demonstrating distinct differences in gene expression profiles and mutations in the DNS S. aureus strains. This knowledge will aid in rapid identification of DNS S. aureus in clinical settings.
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Affiliation(s)
- Zhuo Ma
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - Erica Lasek-Nesselquist
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Jackson Lu
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - Ryan Schneider
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Riddhi Shah
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - George Oliva
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - Janice Pata
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Kathleen McDonough
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Manjunath P. Pai
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - Warren E. Rose
- Universtiy of Wisconsin-Madison, School of Pharmacy, Madison, Wisconsin, United States of America
| | - George Sakoulas
- Center for Immunity, Infection & Inflammation, UCSD School of Medicine, La Jolla, California, United States of America
| | - Meenakshi Malik
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
- * E-mail:
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29
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Chen FJ, Lauderdale TL, Lee CH, Hsu YC, Huang IW, Hsu PC, Yang CS. Effect of a Point Mutation in mprF on Susceptibility to Daptomycin, Vancomycin, and Oxacillin in an MRSA Clinical Strain. Front Microbiol 2018; 9:1086. [PMID: 29887848 PMCID: PMC5980971 DOI: 10.3389/fmicb.2018.01086] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/07/2018] [Indexed: 12/22/2022] Open
Abstract
We previously reported the sequential recovery of daptomycin-nonsusceptible MRSA clinical isolates with an L431F substitution in the MprF protein. The aim of the present study is to determine the effect of this mutation by replacing the mprF gene on the chromosome of a daptomycin-susceptible progenitor strain, CGK5, to obtain CGK5mut having the L431F MprF mutation. Compared to CGK5, the daptomycin and vancomycin MICs of CGK5mut increased from 0.5 to 3 μg/ml and from 1.5 to 3 μg/ml, respectively; however, its oxacillin MIC decreased from 128 to 1 μg/ml in medium without added 2% NaCl. The expression levels of vraSR and several other cell-wall synthesis-related genes were significantly increased in CGK5mut, and the mutant also had significantly reduced negative cell membrane charge, thicker cell wall, and longer doubling time. These features were abolished in the reverse mutant carrying F431L MprF, confirming the pleiotropic effects of the L431F MprF mutation. We believe that this is the first work that shows a single MprF missense mutation can lead to not only changes in the cell membrane but also increased expression of vraSR and subsequently increased resistance to daptomycin and vancomycin while simultaneously conferring increased susceptibility to oxacillin in an isogenic MRSA strain.
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Affiliation(s)
- Feng-Jui Chen
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
| | - Tsai-Ling Lauderdale
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
| | - Chen-Hsiang Lee
- Division of Infectious Diseases, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung, Taiwan
| | - Yu-Chieh Hsu
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
| | - I-Wen Huang
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
| | - Pei-Chi Hsu
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
| | - Chung-Shi Yang
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan, Taiwan
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30
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Yang SJ, Mishra NN, Kang KM, Lee GY, Park JH, Bayer AS. Impact of Multiple Single-Nucleotide Polymorphisms Within mprF on Daptomycin Resistance in Staphylococcus aureus. Microb Drug Resist 2018; 24:1075-1081. [PMID: 29381428 DOI: 10.1089/mdr.2017.0156] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A number of single nucleotide polymorphisms (SNPs) within the mprF open reading frame (ORF) have been associated with daptomycin-resistance (DAP-R) in Staphylococcus aureus. Such SNPs have been found throughout the mprF ORF, although there are clearly preferred "hot spots" within this gene frequently linked to DAP-R phenotype. These mprF SNPs are often correlated with a gain-in-function phenotype, either in terms of increased production (synthase activity) and/or enhanced translocation (translocase activity) of lysyl-phosphatidylglycerol (L-PG) within its cell membrane. However, it is unclear if multiple hot spot mprF SNPs can accumulate within mprF ORFs and cause additive elevations of DAP minimum inhibitory concentrations (MICs). In this study, we used a previously well-characterized plasmid complementation system in S. aureus Newman ΔmprF mutant to express: (1) single point-mutated forms of mprF ORFs cloned from two DAP-R S. aureus strains (mprFS295L or mprFT345A) and (2) dual point-mutated forms of mprF ORFs simultaneously harboring SNPs in the central bifunctional domain and synthase domain in MprF, respectively (mprFS295L+L826F or mprFT345A+L826F). The current study revealed that, although individual hot spot point mutations within mprF ORF can recapitulate signature DAP-R-associated phenotypes (i.e., increased DAP MICs, enhanced surface positive charge, and increased L-PG synthesis), accumulation of such hot spot point mutations paradoxically caused reduction in these latter three metrics.
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Affiliation(s)
- Soo-Jin Yang
- 1 Department of Animal Science and Technology, Chung-Ang University , Anseong-si, Republic of Korea
| | - Nagendra N Mishra
- 2 Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance, California.,3 David Geffen School of Medicine at UCLA , Los Angeles, California
| | - Kyoung-Mi Kang
- 1 Department of Animal Science and Technology, Chung-Ang University , Anseong-si, Republic of Korea
| | - Gi-Yong Lee
- 1 Department of Animal Science and Technology, Chung-Ang University , Anseong-si, Republic of Korea
| | - Jong-Hwan Park
- 4 Laboratory Animal Medicine, College of Veterinary Medicine, Chonnam National University , Gwangju, Republic of Korea
| | - Arnold S Bayer
- 2 Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance, California.,3 David Geffen School of Medicine at UCLA , Los Angeles, California
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31
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Müller A, Grein F, Otto A, Gries K, Orlov D, Zarubaev V, Girard M, Sher X, Shamova O, Roemer T, François P, Becher D, Schneider T, Sahl HG. Differential daptomycin resistance development in Staphylococcus aureus strains with active and mutated gra regulatory systems. Int J Med Microbiol 2017; 308:335-348. [PMID: 29429584 DOI: 10.1016/j.ijmm.2017.12.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 12/13/2017] [Accepted: 12/18/2017] [Indexed: 02/03/2023] Open
Abstract
The first-in-class lipopeptide antibiotic daptomycin (DAP) is highly active against Gram-positive pathogens including ß-lactam and glycopeptide resistant strains. Its molecular mode of action remains enigmatic, since a defined target has not been identified so far and multiple effects, primarily on the cell envelope have been observed. Reduced DAP susceptibility has been described in S. aureus and enterococci after prolonged treatment courses. In line with its pleiotropic antibiotic activities, a unique, defined molecular mechanism of resistance has not emerged, instead non-susceptibility appears often accompanied by alterations in membrane composition and changes in cell wall homeostasis. We compared S. aureus strains HG001 and SG511, which differ primarily in the functionality of the histidine kinase GraS, to evaluate the impact of the GraRS regulatory system on the development of DAP non-susceptibility. After extensive serial passing, both DAPR variants reached a minimal inhibitory concentration of 31 μg/ml and shared some phenotypic characteristics (e.g. thicker cell wall, reduced autolysis). However, based on comprehensive analysis of the underlying genetic, transcriptomic and proteomic changes, we found that both strains took different routes to achieve DAP resistance. Our study highlights the impressive genetic and physiological capacity of S. aureus to counteract pleiotropic activities of cell wall- and membrane-active compounds even when a major cell wall regulatory system is dysfunctional.
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Affiliation(s)
- Anna Müller
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Bonn, Germany; German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn.
| | - Fabian Grein
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Bonn, Germany; German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn
| | - Andreas Otto
- Institute for Microbiology, University of Greifswald, Greifswald, Germany
| | - Kathrin Gries
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Dmitriy Orlov
- Institute for Experimental Medicine, Saint Petersburg, Russia; Saint Petersburg University, Saint Petersburg, Russia
| | - Vladimir Zarubaev
- Pasteur Institute of Epidemiology and Microbiology, Saint Petersburg Russia
| | - Myriam Girard
- Genomic Research Laboratory, Department of Medical Specialties, University Hospitals of Geneva, University of Geneva, Geneva, Switzerland
| | - Xinwei Sher
- Merck & Co., Infectious Diseases, Kenilworth, NJ, USA
| | - Olga Shamova
- Institute for Experimental Medicine, Saint Petersburg, Russia; Saint Petersburg University, Saint Petersburg, Russia
| | | | - Patrice François
- Genomic Research Laboratory, Department of Medical Specialties, University Hospitals of Geneva, University of Geneva, Geneva, Switzerland
| | - Dörte Becher
- Institute for Microbiology, University of Greifswald, Greifswald, Germany
| | - Tanja Schneider
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Bonn, Germany; German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn
| | - Hans-Georg Sahl
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn; Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, University of Bonn, Bonn, Germany
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32
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Characterization of the Mechanisms of Daptomycin Resistance among Gram-Positive Bacterial Pathogens by Multidimensional Lipidomics. mSphere 2017; 2:mSphere00492-17. [PMID: 29242835 PMCID: PMC5729219 DOI: 10.1128/msphere.00492-17] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 11/16/2017] [Indexed: 12/22/2022] Open
Abstract
Previous work suggests that altered lipid metabolism may be associated with daptomycin resistance in Gram-positive pathogens, but lipidomic changes underlying resistance are not fully understood. We performed untargeted lipidomics by using three-dimensional hydrophilic interaction liquid chromatography-ion mobility-mass spectrometry (HILIC-IM-MS) to characterize alterations in the lipidomes of daptomycin-susceptible and -resistant isogenic strain pairs of Enterococcus faecalis, Staphylococcus aureus, and Corynebacterium striatum. We first validated the HILIC-IM-MS method by replicating the expected alterations of phospholipid metabolism in the previously studied E. faecalis strain pairs, such as reduced phosphatidylglycerols (PGs), while also revealing additional changes in cardiolipins (CLs), lysyl-PGs, and glycolipids. Whole-genome sequencing of the S. aureus and C. striatum strains found that daptomycin resistance was associated with mutations in pgsA, which encodes phosphatidylglycerophosphate synthase, as well as mutations in genes affecting fatty acid biosynthesis and cell wall metabolism. Lipidomics revealed significantly decreased levels of PGs, CLs, and amino acid-modified PGs, as well as accumulation of lipids upstream of PGs, such as glycolipids and phosphatidic acids, in the resistant strains. Notably, the glycolipids, diglucosyldiacylglycerols, were significantly elevated in a fatty acid-dependent manner in the daptomycin-resistant S. aureus strain. In daptomycin-resistant C. striatum, which has a unique cell envelope architecture, the glycolipids, glucuronosyldiacylglycerols, and phosphatidylinositols were significantly elevated. These results demonstrate that alteration of lipid metabolism via mutations in pgsA is a common mechanism of daptomycin resistance in two distinct species of Gram-positive bacteria and point to the potential contribution of altered glycolipid and fatty acid compositions to daptomycin resistance. IMPORTANCE This work comprehensively characterizes lipidomic changes underlying daptomycin resistance in three Gram-positive bacterial species, E. faecalis, S. aureus, and C. striatum, by using a novel three-dimensional lipidomics methodology based on advanced mass spectrometry. We demonstrated a number of advantages of our method in comparison with other methods commonly used in the field, such as high molecular specificity, sensitivity, and throughput. Whole-genome sequencing of the S. aureus and C. striatum strains identified mutations in pgsA, which encodes phosphatidylglycerophosphate synthase, in both resistant strains. Lipidomics revealed significantly decreased levels of lipids downstream of PgsA, as well as accumulation of lipids upstream of PgsA in the resistant strains. Furthermore, we found that changes in individual molecular species of each lipid class depend on the their specific fatty acid compositions. The characteristic changes in individual lipid species could be used as biomarkers for identifying underlying resistance mechanisms and for evaluating potential therapies.
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Nam EY, Yang SJ, Kim ES, Cho JE, Park KH, Jung SI, Yoon N, Kim DM, Lee CS, Jang HC, Park Y, Lee KS, Kwak YG, Lee JH, Park SY, Hwang JH, Kim M, Song KH, Kim HB. Emergence of Daptomycin-Nonsusceptible Methicillin-Resistant Staphylococcus aureus Clinical Isolates Among Daptomycin-Naive Patients in Korea. Microb Drug Resist 2017; 24:534-541. [PMID: 29863982 DOI: 10.1089/mdr.2017.0212] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
This study was conducted to assess emergence of daptomycin-nonsusceptible (DAP-NS) phenotype in DAP-naive patients with invasive Staphylococcus aureus (ISA) infections in Korea. A total of 208 S. aureus clinical isolates were selected from a previous prospective study on ISA infections and evaluated for DAP-NS. Although DAP has never been introduced in Korea, five DAP-NS S. aureus strains (2.4%) were identified among 208 S. aureus strains collected from ISA infections. The DAP-NS phenotype was observed only in methicillin-resistant S. aureus (MRSA) strains, but not in methicillin-susceptible S. aureus strains. One DAP-NS MRSA strain belonged to sequence type 72 (ST72) and four were ST5 MRSA strains, three of which were heteroresistant vancomycin (VAN)-intermediate S. aureus. All these five DAP-NS MRSA strains were from healthcare-associated infections without prior exposure to VAN within 30 days. While the ST72 MRSA strain exhibited DAP-NS phenotype via charge repulsion mechanism, four ST5 DAP-NS S. aureus strains had charge-independent DAP-NS mechanism. None of the five DAP-NS strains displayed significant increase in cell wall thickness, indicating that altered cell wall thickness was not associated with the observed DAP-NS phenotype.
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Affiliation(s)
- Eun Young Nam
- 1 Department of Internal Medicine, Seoul National University Bundang Hospital , Seongnam, Republic of Korea.,2 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Soo-Jin Yang
- 3 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Republic of Korea
| | - Eu Suk Kim
- 1 Department of Internal Medicine, Seoul National University Bundang Hospital , Seongnam, Republic of Korea.,2 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Jeong Eun Cho
- 1 Department of Internal Medicine, Seoul National University Bundang Hospital , Seongnam, Republic of Korea
| | - Kyung-Hwa Park
- 4 Department of Internal Medicine, Chonnam National University Hospital , Gwangju, Republic of Korea
| | - Sook-In Jung
- 4 Department of Internal Medicine, Chonnam National University Hospital , Gwangju, Republic of Korea
| | - Nara Yoon
- 5 Department of Internal Medicine, Chosun University Hospital , Gwangju, Republic of Korea
| | - Dong-Min Kim
- 5 Department of Internal Medicine, Chosun University Hospital , Gwangju, Republic of Korea
| | - Chang-Seop Lee
- 6 Department of Internal Medicine, Chonbuk National University , Jeonju, Republic of Korea
| | - Hee-Chang Jang
- 7 Department of Internal Medicine, Chonnam National University Hwasun Hospital , Hwasun, Republic of Korea
| | - Yoonseon Park
- 8 Department of Internal Medicine, National Health Insurance Corporation Ilsan Hospital , Goyang, Republic of Korea
| | - Kkot Sil Lee
- 9 Department of Internal Medicine, Myongji Hospital , Goyang, Republic of Korea
| | - Yee Gyung Kwak
- 10 Department of Internal Medicine, Inje University Ilsan Paik Hospital , Goyang, Republic of Korea
| | - Jae Hoon Lee
- 11 Department of Internal Medicine, Wonkwang University Hospital , Iksan, Republic of Korea
| | - Seong Yeon Park
- 12 Department of Internal Medicine, Dongguk University Ilsan Hospital , Goyang, Republic of Korea
| | - Joo-Hee Hwang
- 1 Department of Internal Medicine, Seoul National University Bundang Hospital , Seongnam, Republic of Korea.,2 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Moonsuk Kim
- 1 Department of Internal Medicine, Seoul National University Bundang Hospital , Seongnam, Republic of Korea.,2 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Kyoung-Ho Song
- 1 Department of Internal Medicine, Seoul National University Bundang Hospital , Seongnam, Republic of Korea.,2 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Hong Bin Kim
- 1 Department of Internal Medicine, Seoul National University Bundang Hospital , Seongnam, Republic of Korea.,2 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
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Kang KM, Mishra NN, Park KT, Lee GY, Park YH, Bayer AS, Yang SJ. Phenotypic and genotypic correlates of daptomycin-resistant methicillin-susceptible Staphylococcus aureus clinical isolates. J Microbiol 2017; 55:153-159. [PMID: 28120188 DOI: 10.1007/s12275-017-6509-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/23/2016] [Accepted: 11/24/2016] [Indexed: 12/28/2022]
Abstract
Daptomycin (DAP) has potent activity in vitro and in vivo against both methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains. DAP-resistance (DAP-R) in S. aureus has been mainly observed in MRSA strains, and has been linked to single nucleotide polymorphisms (SNPs) within the mprF gene leading to altered cell membrane (CM) phospholipid (PL) profiles, enhanced positive surface charge, and changes in CM fluidity. The current study was designed to delineate whether these same genotypic and phenotypic perturbations are demonstrated in clinically-derived DAP-R MSSA strains. We used three isogenic DAP-susceptible (DAP-S)/DAP-R strainpairs and compared: (i) presence of mprF SNPs, (ii) temporal expression profiles of the two key determinants (mprF and dltABCD) of net positive surface charge, (iii) increased production of mprF-dependent lysinylated-phosphatidylglycerol (L-PG), (iv) positive surface charge assays, and (v) susceptibility to cationic host defense peptides (HDPs) of neutrophil and platelet origins. Similar to prior data in MRSA, DAP-R (vs DAP-S) MSSA strains exhibited hallmark hot-spot SNPs in mprF, enhanced and dysregulated expression of both mprF and dltA, L-PG overproduction, HDP resistance and enhanced positive surface charge profiles. However, in contrast to most DAP-R MRSA strains, there were no changes in CM fluidity seen. Thus, charge repulsion via mprF-and dlt-mediated enhancement of positive surface charge may be the main mechanism to explain DAP-R in MSSA strains.
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Affiliation(s)
- Kyoung-Mi Kang
- School of Bioresources and Bioscience, Chung-Ang University, Gyeonggi-do, 17546, Republic of Korea
| | - Nagendra N Mishra
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.,The David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Kun Taek Park
- Department of Veterinary Microbiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Republic of Korea
| | - Gi-Yong Lee
- School of Bioresources and Bioscience, Chung-Ang University, Gyeonggi-do, 17546, Republic of Korea
| | - Yong Ho Park
- Department of Veterinary Microbiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Republic of Korea
| | - Arnold S Bayer
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.,The David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Soo-Jin Yang
- School of Bioresources and Bioscience, Chung-Ang University, Gyeonggi-do, 17546, Republic of Korea.
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35
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The action mechanism of daptomycin. Bioorg Med Chem 2016; 24:6253-6268. [DOI: 10.1016/j.bmc.2016.05.052] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/20/2016] [Accepted: 05/26/2016] [Indexed: 11/15/2022]
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Miller WR, Bayer AS, Arias CA. Mechanism of Action and Resistance to Daptomycin in Staphylococcus aureus and Enterococci. Cold Spring Harb Perspect Med 2016; 6:cshperspect.a026997. [PMID: 27580748 DOI: 10.1101/cshperspect.a026997] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Lipopeptides are natural product antibiotics that consist of a peptide core with a lipid tail with a diverse array of target organisms and mechanisms of action. Daptomycin (DAP) is an example of these compounds with specific activity against Gram-positive organisms. DAP has become increasingly important to combat infections caused by Gram-positive bacteria because of the presence of multidrug resistance in these organisms, particularly in methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). However, emergence of resistance to DAP during therapy is a well-described phenomenon that threatens the clinical use of this antibiotic, limiting further the therapeutic options against both MRSA and VRE. This work will review the historical aspects of the development of DAP, as well as the current knowledge on its mechanism of action and pathways to resistance in a clinically relevant context.
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Affiliation(s)
- William R Miller
- University of Texas Medical School at Houston, Department of Internal Medicine, Division of Infectious Diseases, Houston, Texas 77030
| | - Arnold S Bayer
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California 90502.,David Geffen School of Medicine at UCLA, Los Angeles, California 90095
| | - Cesar A Arias
- University of Texas Medical School at Houston, Department of Internal Medicine, Division of Infectious Diseases, Houston, Texas 77030.,Department of Microbiology and Molecular Genetics, Houston, Texas 77030.,Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia.,International Center for Microbial Genomics, Universidad El Bosque, Bogota, Colombia
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37
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Charretier Y, Schrenzel J. Mass spectrometry methods for predicting antibiotic resistance. Proteomics Clin Appl 2016; 10:964-981. [PMID: 27312049 DOI: 10.1002/prca.201600041] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/09/2016] [Accepted: 06/13/2016] [Indexed: 11/10/2022]
Abstract
Developing elaborate techniques for clinical applications can be a complicated process. Whole-cell MALDI-TOF MS revolutionized reliable microorganism identification in clinical microbiology laboratories and is now replacing phenotypic microbial identification. This technique is a generic, accurate, rapid, and cost-effective growth-based method. Antibiotic resistance keeps emerging in environmental and clinical microorganisms, leading to clinical therapeutic challenges, especially for Gram-negative bacteria. Antimicrobial susceptibility testing is used to reliably predict antimicrobial success in treating infection, but it is inherently limited by the need to isolate and grow cultures, delaying the application of appropriate therapies. Antibiotic resistance prediction by growth-independent methods is expected to reduce the turnaround time. Recently, the potential of next-generation sequencing and microarrays in predicting microbial resistance has been demonstrated, and this review evaluates the potential of MS in this field. First, technological advances are described, and the possibility of predicting antibiotic resistance by MS is then illustrated for three prototypical human pathogens: Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Clearly, MS methods can identify antimicrobial resistance mediated by horizontal gene transfers or by mutations that affect the quantity of a gene product, whereas antimicrobial resistance mediated by target mutations remains difficult to detect.
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Affiliation(s)
- Yannick Charretier
- Genomic Research Laboratory, Division of Infectious Diseases, Geneva University Hospitals.
| | - Jacques Schrenzel
- Genomic Research Laboratory, Division of Infectious Diseases, Geneva University Hospitals
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Munita JM, Bayer AS, Arias CA. Evolving resistance among Gram-positive pathogens. Clin Infect Dis 2016; 61 Suppl 2:S48-57. [PMID: 26316558 DOI: 10.1093/cid/civ523] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Antimicrobial therapy is a key component of modern medical practice and a cornerstone for the development of complex clinical interventions in critically ill patients. Unfortunately, the increasing problem of antimicrobial resistance is now recognized as a major public health threat jeopardizing the care of thousands of patients worldwide. Gram-positive pathogens exhibit an immense genetic repertoire to adapt and develop resistance to virtually all antimicrobials clinically available. As more molecules become available to treat resistant gram-positive infections, resistance emerges as an evolutionary response. Thus, antimicrobial resistance has to be envisaged as an evolving phenomenon that demands constant surveillance and continuous efforts to identify emerging mechanisms of resistance to optimize the use of antibiotics and create strategies to circumvent this problem. Here, we will provide a broad perspective on the clinical aspects of antibiotic resistance in relevant gram-positive pathogens with emphasis on the mechanistic strategies used by these organisms to avoid being killed by commonly used antimicrobial agents.
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Affiliation(s)
- Jose M Munita
- Division of Infectious Diseases, Department of Internal Medicine International Center for Microbial Genomics Clinica Alemana de Santiago, Universidad del Desarrollo, Chile
| | - Arnold S Bayer
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Cesar A Arias
- Division of Infectious Diseases, Department of Internal Medicine Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston International Center for Microbial Genomics Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia
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39
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Bayer AS, Mishra NN, Cheung AL, Rubio A, Yang SJ. Dysregulation of mprF and dltABCD expression among daptomycin-non-susceptible MRSA clinical isolates. J Antimicrob Chemother 2016; 71:2100-4. [PMID: 27121398 DOI: 10.1093/jac/dkw142] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 03/24/2016] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND In small series or individual reports, SNPs within the mprF ORF and dysregulation of its expression in Staphylococcus aureus have been linked to daptomycin resistance (DAP-R) via a proposed gain-in-function mechanism. Similarly, dysregulation of dltABCD has also been associated with DAP-R. METHODS Using 22 well-characterized, isogenic daptomycin-susceptible (DAP-S)/DAP-R clinical MRSA strain pairs, we assessed potential relationships of the DAP-R phenotype with: (i) regulation of mprF transcription; (ii) regulation of dltABCD transcription; (iii) expression of the two-component regulatory system, graRS (upstream regulator for both mprF and dltABCD transcription); (iv) SNPs within the graRS promoter or its ORF; and (v) altered mprF transcription and lysyl-phosphatidylglycerol (L-PG) synthesis. RESULTS Enhanced expression of mprF occurred with SNPs in highly distinct and well-chronicled MprF domain 'hot spots' and rarely occurred without such mutations. Increased expression and/or dysregulation of mprF and dltABCD were not uncommon in DAP-R strains, occurring in 27% of strains for each gene. In these latter strains, neither graRS expression profiles nor polymorphic sequences within the graRS promoter or ORF could be significantly linked to altered transcription of mprF or dlt. CONCLUSIONS Although graRS can co-regulate mprF and dltABCD expression, loci outside of this regulon appear to be involved in dysregulation of these latter two genes and the DAP-R phenotype. Finally, DAP-R strains exhibiting significantly altered mprF transcription profiles produced significantly increased levels of L-PG.
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Affiliation(s)
- Arnold S Bayer
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Nagendra N Mishra
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA The David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Ambrose L Cheung
- Department of Microbiology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | | | - Soo-Jin Yang
- School of Bioresources and Bioscience, Chung-Ang University, 4726 Seodong-daero, Daedeok-myeon, Anseong-si, Gyeonggi-do 456-756, Republic of Korea
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40
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Daptomycin Tolerance in the Staphylococcus aureus pitA6 Mutant Is Due to Upregulation of the dlt Operon. Antimicrob Agents Chemother 2016; 60:2684-91. [PMID: 26883712 DOI: 10.1128/aac.03022-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/03/2016] [Indexed: 02/01/2023] Open
Abstract
Understanding the mechanisms of how bacteria become tolerant toward antibiotics during clinical therapy is a very important object. In a previous study, we showed that increased daptomycin (DAP) tolerance of Staphylococcus aureus was due to a point mutation in pitA (inorganic phosphate transporter) that led to intracellular accumulation of both inorganic phosphate (Pi) and polyphosphate (polyP). DAP tolerance in the pitA6 mutant differs from classical resistance mechanisms since there is no increase in the MIC. In this follow-up study, we demonstrate that DAP tolerance in the pitA6 mutant is not triggered by the accumulation of polyP. Transcriptome analysis revealed that 234 genes were at least 2.0-fold differentially expressed in the mutant. Particularly, genes involved in protein biosynthesis, carbohydrate and lipid metabolism, and replication and maintenance of DNA were downregulated. However, the most important change was the upregulation of the dlt operon, which is induced by the accumulation of intracellular Pi The GraXRS system, known as an activator of the dlt operon (d-alanylation of teichoic acids) and of the mprF gene (multiple peptide resistance factor), is not involved in DAP tolerance of the pitA6 mutant. In conclusion, DAP tolerance of the pitA6 mutant is due to an upregulation of the dlt operon, triggered directly or indirectly by the accumulation of Pi.
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41
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Lin YT, Tsai JC, Yamamoto T, Chen HJ, Hung WC, Hsueh PR, Teng LJ. Emergence of a small colony variant of vancomycin-intermediateStaphylococcus aureusin a patient with septic arthritis during long-term treatment with daptomycin. J Antimicrob Chemother 2016; 71:1807-14. [DOI: 10.1093/jac/dkw060] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 02/15/2016] [Indexed: 11/13/2022] Open
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Steinbuch KB, Fridman M. Mechanisms of resistance to membrane-disrupting antibiotics in Gram-positive and Gram-negative bacteria. MEDCHEMCOMM 2016. [DOI: 10.1039/c5md00389j] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A diverse repertoire of mechanisms has evolved to confer resistance to bacterial membrane disrupting antimicrobial cationic amphiphiles.
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Affiliation(s)
- Kfir B. Steinbuch
- School of Chemistry
- Beverly Raymond Sackler Faculty of Exact Sciences
- Tel Aviv University
- Tel Aviv
- Israel
| | - Micha Fridman
- School of Chemistry
- Beverly Raymond Sackler Faculty of Exact Sciences
- Tel Aviv University
- Tel Aviv
- Israel
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43
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Jiang JH, Peleg AY. Daptomycin-Nonsusceptible Staphylococcus aureus: The Role of Combination Therapy with Daptomycin and Gentamicin. Genes (Basel) 2015; 6:1256-67. [PMID: 26633517 PMCID: PMC4690039 DOI: 10.3390/genes6041256] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 11/05/2015] [Accepted: 11/16/2015] [Indexed: 11/16/2022] Open
Abstract
Reduced susceptibility to daptomycin in Staphylococcus aureus has now been described, leading to clinical failures. Here we determined the impact of daptomycin and gentamicin combination therapy on bactericidal activity and resistance emergence using daptomycin-susceptible and -resistant isolates with mutations linked to previous daptomycin or vancomycin exposure. Enhanced killing of S. aureus was observed when gentamicin was combined with daptomycin, most commonly with daptomycin concentrations below the peak serum free-drug concentrations achieved with standard dosing. Synergy was seen with daptomycin-susceptible isolates and with isolates resistant to vancomycin and daptomycin. Combination therapy also prevented the emergence of resistance. Daptomycin and gentamicin combination therapy may provide the synergy required to prevent emergence of resistance when daptomycin levels are below peak serum concentrations as would be found in deep-seated, complicated infections.
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Affiliation(s)
- Jhih-Hang Jiang
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
| | - Anton Y Peleg
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
- Department of Infectious Diseases, The Alfred Hospital and Central Clinical School, Monash University, Melbourne, Victoria 3004, Australia.
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44
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Abstract
Daptomycin (DAP) is a cyclic lipopeptide with in vitro activity against a variety of Gram-positive pathogens, including multidrug-resistant organisms. Since its introduction into clinical practice in 2003, DAP has become an important key frontline antibiotic for severe or deep-seated infections caused by Gram-positive organisms. Unfortunately, DAP resistance (DAP-R) has been extensively documented in clinically important organisms such as Staphylococcus aureus, Enterococcus spp., and Streptococcus spp. Studies on the mechanisms of DAP-R in Bacillus subtilis and other Gram-positive bacteria indicate that the genetic pathways of DAP-R are diverse and complex. However, a common phenomenon emerging from these mechanistic studies is that DAP-R is associated with important adaptive changes in cell wall and cell membrane homeostasis with critical changes in cell physiology. Findings related to these adaptive changes have provided novel insights into the genetics and molecular mechanisms of bacterial cell envelope stress response and the manner in which Gram-positive bacteria cope with the antimicrobial peptide attack and protect vital structures of the cell envelope, such as the cell membrane. In this review, we will examine the most recent findings related to the molecular mechanisms of resistance to DAP in relevant Gram-positive pathogens and discuss the clinical implications for therapy against these important bacteria.
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Affiliation(s)
- Truc T Tran
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical School at Houston, Houston, Texas.,International Center for Microbial Genomics, Universidad El Bosque, Bogota, Colombia
| | - Jose M Munita
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical School at Houston, Houston, Texas.,International Center for Microbial Genomics, Universidad El Bosque, Bogota, Colombia.,Clinica Alemana de Santiago, Universidad del Desarrollo, Santiago, Chile
| | - Cesar A Arias
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical School at Houston, Houston, Texas.,International Center for Microbial Genomics, Universidad El Bosque, Bogota, Colombia.,Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas.,Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia
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45
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Stefani S, Campanile F, Santagati M, Mezzatesta ML, Cafiso V, Pacini G. Insights and clinical perspectives of daptomycin resistance in Staphylococcus aureus: A review of the available evidence. Int J Antimicrob Agents 2015; 46:278-89. [DOI: 10.1016/j.ijantimicag.2015.05.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 05/13/2015] [Indexed: 02/04/2023]
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46
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Chen CJ, Huang YC, Chiu CH. Multiple pathways of cross-resistance to glycopeptides and daptomycin in persistent MRSA bacteraemia. J Antimicrob Chemother 2015. [PMID: 26216581 DOI: 10.1093/jac/dkv225] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The development of non-susceptibility to glycopeptides and daptomycin in MRSA during persistent bacteraemia has become a significant therapeutic challenge. However, the in vivo evolution and mechanism of the dual resistance have remained incompletely understood. METHODS A series of MRSA blood isolates with incremental non-susceptibility to glycopeptides and daptomycin were consecutively recovered from a bacteraemic patient who was failing chemotherapy. The evolutionary pathways during conversion from a glycopeptide- and daptomycin-susceptible phenotype into a vancomycin-intermediate Staphylococcus aureus (VISA) and a daptomycin-resistant S. aureus (DRSA) phenotype were then traced by WGS of the isogenic strains. RESULTS A total of six non-synonymous mutations and three evolutionary pathways were identified during the development of the VISA/DRSA phenotype. The first pathway involved two steps of evolution, with an initial 1 bp insertion into yycH and a subsequent gain-in-function point mutation in mprF (S295L). The two mutations were correlated with heteroresistance to daptomycin/vancomycin and full development of the VISA/DRSA phenotype. The second pathway involved an 11 bp deletion mutation in yycH and point mutations at two genes, correlating with the development of the VISA phenotype and heteroresistance to daptomycin. Mutation in mprF (S295L) and a 5 bp deletion mutation in yycH were identified in the third pathway and corresponded to conversion into the full VISA/DRSA phenotype. The mutations in yycH resulted in premature terminations of YycH with variable lengths. CONCLUSIONS Multiple evolutionary pathways involving yycH and mprF can proceed simultaneously and may mediate cross-resistance to glycopeptides and daptomycin during persistent MRSA bacteraemia under antibiotic selective pressure.
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Affiliation(s)
- Chih-Jung Chen
- Division of Paediatric Infectious Diseases, Department of Paediatrics, Chang Gung Children's Hospital and Chang Gung Memorial Hospital, 333 Taoyuan, Taiwan College of Medicine, Chang Gung University, 333 Taoyuan, Taiwan
| | - Yhu-Chering Huang
- Division of Paediatric Infectious Diseases, Department of Paediatrics, Chang Gung Children's Hospital and Chang Gung Memorial Hospital, 333 Taoyuan, Taiwan College of Medicine, Chang Gung University, 333 Taoyuan, Taiwan
| | - Cheng-Hsu Chiu
- Division of Paediatric Infectious Diseases, Department of Paediatrics, Chang Gung Children's Hospital and Chang Gung Memorial Hospital, 333 Taoyuan, Taiwan College of Medicine, Chang Gung University, 333 Taoyuan, Taiwan
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47
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Frequency and Distribution of Single-Nucleotide Polymorphisms within mprF in Methicillin-Resistant Staphylococcus aureus Clinical Isolates and Their Role in Cross-Resistance to Daptomycin and Host Defense Antimicrobial Peptides. Antimicrob Agents Chemother 2015; 59:4930-7. [PMID: 26055370 DOI: 10.1128/aac.00970-15] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 05/31/2015] [Indexed: 12/16/2022] Open
Abstract
MprF is responsible for the lysinylation of phosphatidylglycerol (PG) to synthesize the positively charged phospholipid (PL) species, lysyl-PG (L-PG). It has been proposed that the single-nucleotide polymorphisms (SNPs) within the mprF open reading frame (ORF) are associated with a gain-in-function phenotype in terms of daptomycin resistance in Staphylococcus aureus. (Note that although the official term is daptomycin nonsusceptibility, we use the term daptomycin resistance in this paper for ease of presentation.) Using 22 daptomycin-susceptible (DAP(s))/daptomycin-resistant (DAP(r)) clinical methicillin-resistant S. aureus (MRSA) strain pairs, we assessed (i) the frequencies and distribution of putative mprF gain-in-function SNPs, (ii) the relationships of the SNPs to both daptomycin resistance and cross-resistance to the prototypical endovascular host defense peptide (HDP) thrombin-induced platelet microbicidal protein (tPMP), and (iii) the impact of mprF SNPs on positive surface charge phenotype and modifications of membrane PL profiles. Most of the mprF SNPs identified in our DAP(r) strains were clustered within the two MprF loci, (i) the central bifunctional domain and (ii) the C-terminal synthase domain. Moreover, we were able to correlate the presence and location of mprF SNPs in DAP(r) strains with HDP cross-resistance, positive surface charge, and L-PG profiles. Although DAP(r) strains with mprF SNPs in the bifunctional domain showed higher resistance to tPMPs than DAP(r) strains with SNPs in the synthase domain, this relationship was not observed in positive surface charge assays. These results demonstrated that both charge-mediated and -unrelated mechanisms are involved in DAP resistance and HDP cross-resistance in S. aureus.
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48
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Staphylococcus aureus metabolic adaptations during the transition from a daptomycin susceptibility phenotype to a daptomycin nonsusceptibility phenotype. Antimicrob Agents Chemother 2015; 59:4226-38. [PMID: 25963986 DOI: 10.1128/aac.00160-15] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/29/2015] [Indexed: 02/07/2023] Open
Abstract
Staphylococcus aureus is a major cause of nosocomial and community-acquired infections. The success of S. aureus as a pathogen is due in part to its many virulence determinants and resistance to antimicrobials. In particular, methicillin-resistant S. aureus has emerged as a major cause of infections and led to increased use of the antibiotics vancomycin and daptomycin, which has increased the isolation of vancomycin-intermediate S. aureus and daptomycin-nonsusceptible S. aureus strains. The most common mechanism by which S. aureus acquires intermediate resistance to antibiotics is by adapting its physiology and metabolism to permit growth in the presence of these antibiotics, a process known as adaptive resistance. To better understand the physiological and metabolic changes associated with adaptive resistance, six daptomycin-susceptible and -nonsusceptible isogenic strain pairs were examined for changes in growth, competitive fitness, and metabolic alterations. Interestingly, daptomycin nonsusceptibility coincides with a slightly delayed transition to the postexponential growth phase and alterations in metabolism. Specifically, daptomycin-nonsusceptible strains have decreased tricarboxylic acid cycle activity, which correlates with increased synthesis of pyrimidines and purines and increased carbon flow to pathways associated with wall teichoic acid and peptidoglycan biosynthesis. Importantly, these data provided an opportunity to alter the daptomycin nonsusceptibility phenotype by manipulating bacterial metabolism, a first step in developing compounds that target metabolic pathways that can be used in combination with daptomycin to reduce treatment failures.
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Abstract
Gram-positive organisms, including the pathogens Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecalis, have dynamic cell envelopes that mediate interactions with the environment and serve as the first line of defense against toxic molecules. Major components of the cell envelope include peptidoglycan (PG), which is a well-established target for antibiotics, teichoic acids (TAs), capsular polysaccharides (CPS), surface proteins, and phospholipids. These components can undergo modification to promote pathogenesis, decrease susceptibility to antibiotics and host immune defenses, and enhance survival in hostile environments. This chapter will cover the structure, biosynthesis, and important functions of major cell envelope components in gram-positive bacteria. Possible targets for new antimicrobials will be noted.
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Hanses F, Roux C, Dunman PM, Salzberger B, Lee JC. Staphylococcus aureus gene expression in a rat model of infective endocarditis. Genome Med 2014; 6:93. [PMID: 25392717 PMCID: PMC4228149 DOI: 10.1186/s13073-014-0093-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/20/2014] [Indexed: 01/04/2023] Open
Abstract
Background Diabetes mellitus is a frequent underlying comorbidity in patients with Staphylococcus aureus endocarditis, and it represents a risk factor for complications and a negative outcome. The pathogenesis of staphylococcal endocardial infections in diabetic hosts has been poorly characterized, and little is known about S. aureus gene expression in endocardial vegetations. Methods We utilized a rat model of experimental S. aureus endocarditis to compare the pathogenesis of staphylococcal infection in diabetic and nondiabetic hosts and to study the global S. aureus transcriptome in endocardial vegetations in vivo. Results Diabetic rats had higher levels of bacteremia and larger endocardial vegetations than nondiabetic control animals. Microarray analyses revealed that 61 S. aureus genes were upregulated in diabetic rats, and the majority of these bacterial genes were involved in amino acid and carbohydrate metabolism. When bacterial gene expression in vivo (diabetic or nondiabetic endocardial vegetations) was compared to in vitro growth conditions, higher in vivo expression of genes encoding toxins and proteases was observed. Additionally, genes involved in the production of adhesins, capsular polysaccharide, and siderophores, as well as in amino acid and carbohydrate transport and metabolism, were upregulated in endocardial vegetations. To test the contribution of selected upregulated genes to the pathogenesis of staphylococcal endocarditis, isogenic deletion mutants were utilized. A mutant defective in production of the siderophore staphyloferrin B was attenuated in the endocarditis model, whereas the virulence of a surface adhesin (ΔsdrCDE) mutant was similar to that of the parental S. aureus strain. Conclusions Our results emphasize the relevance of diabetes mellitus as a risk factor for infectious endocarditis and provide a basis for understanding gene expression during staphylococcal infections in vivo. Electronic supplementary material The online version of this article (doi:10.1186/s13073-014-0093-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Frank Hanses
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115 USA ; Department of Internal Medicine I, University Hospital Regensburg, Franz-Josef-Strauss Allee 11, Regensburg, 93049 Germany
| | - Christelle Roux
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642 USA
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642 USA
| | - Bernd Salzberger
- Department of Internal Medicine I, University Hospital Regensburg, Franz-Josef-Strauss Allee 11, Regensburg, 93049 Germany
| | - Jean C Lee
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115 USA
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