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Bicarbonate Resensitization of Methicillin-Resistant Staphylococcus aureus to β-Lactam Antibiotics. Antimicrob Agents Chemother 2019; 63:AAC.00496-19. [PMID: 31010857 PMCID: PMC6591647 DOI: 10.1128/aac.00496-19] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 04/07/2019] [Indexed: 12/24/2022] Open
Abstract
Endovascular infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are a major health care concern, especially infective endocarditis (IE). Standard antimicrobial susceptibility testing (AST) defines most MRSA strains as “resistant” to β-lactams, often leading to the use of costly and/or toxic treatment regimens. In this investigation, five prototype MRSA strains, representing the range of genotypes in current clinical circulation, were studied. Endovascular infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are a major health care concern, especially infective endocarditis (IE). Standard antimicrobial susceptibility testing (AST) defines most MRSA strains as “resistant” to β-lactams, often leading to the use of costly and/or toxic treatment regimens. In this investigation, five prototype MRSA strains, representing the range of genotypes in current clinical circulation, were studied. We identified two distinct MRSA phenotypes upon AST using standard media, with or without sodium bicarbonate (NaHCO3) supplementation: one highly susceptible to the antistaphylococcal β-lactams oxacillin and cefazolin (NaHCO3 responsive) and one resistant to such agents (NaHCO3 nonresponsive). These phenotypes accurately predicted clearance profiles of MRSA from target tissues in experimental MRSA IE treated with each β-lactam. Mechanistically, NaHCO3 reduced the expression of two key genes involved in the MRSA phenotype, mecA and sarA, leading to decreased production of penicillin-binding protein 2a (that mediates methicillin resistance), in NaHCO3-responsive (but not in NaHCO3-nonresponsive) strains. Moreover, both cefazolin and oxacillin synergistically killed NaHCO3-responsive strains in the presence of the host defense antimicrobial peptide (LL-37) in NaHCO3-supplemented media. These findings suggest that AST of MRSA strains in NaHCO3-containing media may potentially identify infections caused by NaHCO3-responsive strains that are appropriate for β-lactam therapy.
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Dupieux C, Trouillet-Assant S, Tasse J, Freydière AM, Raulin O, Roure-Sobas C, Salord H, Tigaud S, Laurent F. Evaluation of a commercial immunochromatographic assay for rapid routine identification of PBP2a-positive Staphylococcus aureus and coagulase-negative staphylococci. Diagn Microbiol Infect Dis 2016; 86:262-264. [DOI: 10.1016/j.diagmicrobio.2016.08.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 08/03/2016] [Accepted: 08/10/2016] [Indexed: 11/26/2022]
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Li L, Cheung A, Bayer AS, Chen L, Abdelhady W, Kreiswirth BN, Yeaman MR, Xiong YQ. The Global Regulon sarA Regulates β-Lactam Antibiotic Resistance in Methicillin-Resistant Staphylococcus aureus In Vitro and in Endovascular Infections. J Infect Dis 2016; 214:1421-1429. [PMID: 27543672 DOI: 10.1093/infdis/jiw386] [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: 04/25/2016] [Accepted: 08/11/2016] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The global regulator sarA modulates virulence of methicillin-resistant Staphylococcus aureus (MRSA) via regulation of principal virulence factors (eg, adhesins and toxins) and biofilm formation. Resistance of S. aureus strains to β-lactam antibiotics (eg, oxacillin) depends on the production of penicillin-binding protein 2a (PBP2a), encoded by mecA METHODS: In the present study, we investigated the impact of sarA on the phenotypic and genotypic characteristics of oxacillin resistance both in vitro and in an experimental endocarditis model, using prototypic healthcare- and community-associated MRSA parental and their respective sarA mutant strain sets. RESULTS All sarA mutants (vs respective MRSA parental controls) displayed significant reductions in oxacillin resistance and biofilm formation in vitro and oxacillin persistence in an experimental endocarditis model in vivo. These phenotypes corresponded to reduced mecA expression and PBP2a production and an interdependency of sarA and sigB regulators. Moreover, RNA sequencing analyses showed that sarA mutants exhibited significantly increased levels of primary extracellular proteases and suppressed pyrimidine biosynthetic pathway, argininosuccinate lyase-encoding, and ABC transporter-related genes as compared to the parental strain. CONCLUSIONS These results suggested that sarA regulates oxacillin resistance in mecA-positive MRSA. Thus, abrogation of this regulator represents an attractive and novel drug target to potentiate efficacy of existing antibiotic for MRSA therapy.
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Affiliation(s)
- Liang Li
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center
| | | | - Arnold S Bayer
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center.,Division of Infectious Diseases.,David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Liang Chen
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark
| | - Wessam Abdelhady
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center
| | - Barry N Kreiswirth
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark
| | - Michael R Yeaman
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center.,Division of Infectious Diseases.,Division of Molecular Medicine, Los Angeles County-Harbor-UCLA Medical Center, Torrance.,David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Yan Q Xiong
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center.,Division of Infectious Diseases.,David Geffen School of Medicine at UCLA, Los Angeles, California
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Bressler AM, Williams T, Culler EE, Zhu W, Lonsway D, Patel JB, Nolte FS. Correlation of penicillin Binding protein 2a detection with oxacillin resistance in Staphylococcus aureus and discovery of a novel penicillin binding protein 2a mutation. J Clin Microbiol 2005; 43:4541-4. [PMID: 16145104 PMCID: PMC1234091 DOI: 10.1128/jcm.43.9.4541-4544.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We compared a rapid slide latex agglutination test (LAT; Oxoid, Basingstoke, United Kingdom) that detects penicillin binding protein 2a (PBP2a) with MicroScan conventional panels (Dade Behring, West Sacramento, CA) for detection of oxacillin resistance in Staphylococcus aureus. The PBP2a LAT demonstrated 99% agreement with MicroScan oxacillin MIC results for 388 isolates of S. aureus. All 249 oxacillin-resistant isolates gave strong positive reactions in the LAT (100% sensitivity). Three of the 139 oxacillin-susceptible isolates were also strongly positive and one was weakly positive in the LAT (97.1% specificity). The three oxacillin-susceptible isolates with strongly positive reactions were further characterized. The mecA gene was detected in all three by PCR; one isolate was determined to be resistant to oxacillin by reference broth microdilution testing (MIC, 8 microg/ml), one isolate was inducibly resistant to oxacillin (MIC of 16 microg/ml after overnight induction), and one isolate remained susceptible regardless of the method used for testing. Sequence analysis of a 2.1-kb gene fragment of the mecA gene from the susceptible isolate revealed a one-base substitution at nucleotide position 1449 which results in a Met-to-Ile change for amino acid residue 483. This amino acid substitution has not been previously reported and may be associated with a change in the function of PBP2a resulting in oxacillin susceptibility. An additional 487 isolates were tested in parallel with the both the LAT and MicroScan panels using criteria in which only strong (3 to 4+) or repeatedly weak (1 to 2+) LAT reactions were considered positive, and the results showed 99.4% agreement. The PBP2a LAT provided rapid and reliable detection of oxacillin resistance and proved a useful adjunct to the phenotypic method. Both methods provided reliable detection of oxacillin-resistant S. aureus and facilitated the discovery of a novel, functionally impaired form of PBP2a.
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Affiliation(s)
- Adam M Bressler
- Deparment of Pathology and Laboratory Medicine, Emory University Hospital, Atlanta, GA 30322, USA
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Wu SJ, Chan A, Kado CI. Detection of PCR amplicons from bacterial pathogens using microsphere agglutination. J Microbiol Methods 2004; 56:395-400. [PMID: 14967231 DOI: 10.1016/j.mimet.2003.11.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2003] [Revised: 11/04/2003] [Accepted: 11/11/2003] [Indexed: 10/26/2022]
Abstract
For rapid and inexpensive detection of polymerase chain reaction (PCR) amplicons, a novel microsphere agglutination assay has been developed. PCR is carried out using biotinylated forward and reverse primers, and the amplified DNA fragments are able to agglutinate streptavidin-coated microspheres (5.7 microm in diameter). Purification of PCR amplicons is unnecessary when initial primer concentrations are 250 nM. Agglutination can be identified visually within 2 min without any additional equipment or reagents. Using listeriolysin (lisA)-specific biotinylated primers, we have successfully detected and identified Listeria monocytogenes lisA+ cells among Salmonella typhimurium, Staphylococcus aureus, Campylobacter jejuni and Escherichia coli O157:H7 cells. The simplicity of this protocol considerably reduces the time and cost of diagnostic PCR experiments. This procedure is potentially useful for various studies and field applications.
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Affiliation(s)
- Shaw-Jye Wu
- Department of Life Science, National Central University, Jhong-li City, Taoyuan, Taiwan.
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Hamze M, Dabboussi F, Daher W, Izard D. [Antibiotic resistance of Staphylococcus aureus at north Lebanon: place of the methicillin resistance and comparison of detection methods]. PATHOLOGIE-BIOLOGIE 2003; 51:21-6. [PMID: 12628288 DOI: 10.1016/s0369-8114(02)00315-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The aim of this study was to evaluate the susceptibility of 100 Staphylococcus aureus strains isolated from the laboratory of Microbiology of the Islami Hospital of Tripoli (Lebanon) to 19 antibiotics, and to determine the prevalence of methicillin resistant strains. 30% of strains studied were methicillin resistant, 96% were resistant to the penicillin G. Clavulanic acid restaurated the amoxicillin activity to 29%. The resistance level was 34% for amikacin, 3% for gentamycin and tobramycin, 10% for chloramphenicol, 44.33% for tetracyclin, 7% for erythromycin, 4.04% for clindamycin, 20% for trimethoprim-sulfametoxasol and 0% for vancomycin and teicoplanin. The methicillin-resistant Staphylococcus aureus possess more important resistant level in comparison with the methicillin sensitive strains. We compared the ability of latex agglutination test (Slidex(R) SARM, bioMérieux, France) to detect the production of penicillin-binding protein 2' (PBP 2') in 100 clinical isolates of S. aureus with two reference methods: the oxacillin disk diffusion test and the MIC determination by the E-test (AB BIODISK, Sweden). The two reference methods give the same results for the detection of methicillin resistant S. aureus. The Slidex test was positive for all 30 isolates determined to be methicillin resistant by the reference methods (sensitivity 100%). The latex test was negative for 42 of 70 isolates determined to be methicillin susceptible by the reference methods, and the latex test was positive for 28 isolates determined to be susceptible (specificity 60%).
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Affiliation(s)
- M Hamze
- Faculté de Santé Publique, Section 3, Université Libanaise, P.O. Box 246, Tripoli, Liban.
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Scanvic-Hameg A, May-Michelangeli L, Le Turdu F. Apport du kit Servitex Staphylocoque MRSA® dans le diagnostic rapide des souches de Staphylococcus aureus résistantes à la méticilline. Med Mal Infect 2002. [DOI: 10.1016/s0399-077x(01)00327-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Sakoulas G, Gold HS, Venkataraman L, DeGirolami PC, Eliopoulos GM, Qian Q. Methicillin-resistant Staphylococcus aureus: comparison of susceptibility testing methods and analysis of mecA-positive susceptible strains. J Clin Microbiol 2001; 39:3946-51. [PMID: 11682512 PMCID: PMC88469 DOI: 10.1128/jcm.39.11.3946-3951.2001] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for an increasing number of serious nosocomial and community-acquired infections. Phenotypic heterogeneous drug resistance (heteroresistance) to antistaphylococcal beta-lactams affects the results of susceptibility testing. The present study compared the MRSA-Screen latex agglutination test (Denka Seiken Co., Ltd., Tokyo, Japan) for detection of PBP 2a with agar dilution, the VITEK-1 and VITEK-2 systems (bioMérieux, St. Louis, Mo.), and the oxacillin agar screen test for detection of MRSA, with PCR for the mecA gene used as the "gold standard" assay. Analysis of 107 methicillin-susceptible S. aureus (MSSA) isolates and 203 MRSA isolates revealed that the MRSA-Screen latex agglutination test is superior to any single phenotype-based susceptibility testing method, with a sensitivity of 100% and a specificity of 99.1%. Only one isolate that lacked mecA was weakly positive by the MRSA-Screen latex agglutination test. This isolate was phenotypically susceptible to oxacillin and did not contain the mecA gene by Southern blot hybridization. The oxacillin agar screen test, the VITEK-1 system, the VITEK-2 system, and agar dilution showed sensitivities of 99.0, 99.0, 99.5, and 99%, respectively, and specificities of 98.1, 100, 97.2, and 100%, respectively. The differences in sensitivity or specificity were not statistically significant. Oxacillin bactericidal assays showed that mecA- and PBP 2a-positive S. aureus isolates that are susceptible to antistaphylococcal beta-lactams by conventional methods are functionally resistant to oxacillin. We conclude that the accuracy of the MRSA-Screen latex agglutination method for detection of PBP 2a approaches the accuracy of PCR and is more accurate than any susceptibility testing method used alone for the detection of MRSA.
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Affiliation(s)
- G Sakoulas
- Division of Infectious Diseases, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
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Swenson JM, Williams PP, Killgore G, O'Hara CM, Tenover FC. Performance of eight methods, including two new rapid methods, for detection of oxacillin resistance in a challenge set of Staphylococcus aureus organisms. J Clin Microbiol 2001; 39:3785-8. [PMID: 11574619 PMCID: PMC88435 DOI: 10.1128/jcm.39.10.3785-3788.2001] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Using a set of 55 Staphylococcus aureus challenge organisms, we evaluated six routine methods (broth microdilution, disk diffusion, oxacillin agar screen, MicroScan conventional panels, MicroScan rapid panels, and Vitek cards) currently used in many clinical laboratories and two new rapid methods, Velogene and the MRSA-Screen, that require less than a day to determine the susceptibility of S. aureus to oxacillin. The methods were evaluated by using the presence of the mecA gene, as detected by PCR, as the "gold standard." The strains included 19 mecA-positive heterogeneously resistant strains of expression class 1 or 2 (demonstrating oxacillin MICs of 4 to >16 microg/ml) and 36 mecA-negative strains. The oxacillin MICs of the latter strains were 0.25 to 4 microg/ml when tested by broth microdilution with 2% NaCl-supplemented cation-adjusted Mueller-Hinton broth as specified by the NCCLS. However, when tested by agar dilution with 4% salt (the conditions used in the oxacillin agar screen method), the oxacillin MICs of 16 of the mecA-negative strains increased to 4 to 8 microg/ml. On initial testing, the percentages of correct results (% sensitivity/% specificity) were as follows: broth microdilution, 100/100; Velogene, 100/100; Vitek, 95/97; oxacillin agar screen, 90/92; disk diffusion, 100/89; MicroScan rapid panels, 90/86; MRSA-Screen, 90/100; and MicroScan conventional, 74/97. The MRSA-Screen sensitivity improved to 100% if agglutination reactions were read at 15 min. Repeat testing improved the performance of some but not all of the systems.
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Affiliation(s)
- J M Swenson
- Epidemiology and Laboratory Branch, Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
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