Loss of the<i>mecA</i>Gene during Storage of Methicillin-Resistant<i>Staphylococcus aureus</i>Strains

Griethuysen, Arjanne van; Loo, Inge van; Belkum, Alex van; Vandenbroucke-Grauls, Christina M. J. E.; Wannet, W J B; Keulen, P. van; Kluytmans, Jan

doi:10.1128/jcm.43.3.1361-1365.2005

Cited by 50 publications

(42 citation statements)

References 13 publications

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“…Our qPCR assay consists of the multiplex PCR amplification of the mecA and the femA genes from S. aureus and S. epidermidis and allows the identification of the origin of the mecA signal. Obviously, this triplex PCR was applied to isolated MRSA and MSSA isolates to assess its ability to reliably detect the S. aureus femA gene and, simultaneously, to potentially excise the mecA gene after the isolates are thawed (23). The results of the assay were in complete concordance with the results obtained by standard culturebased methods (Table 1).…”

supporting

confidence: 61%

“…Donnio described that the partial excision of SCCmec occurs not infrequently and might explain some of the false-positive results (9). Freezing-thawing has been suggested as a potential cause of mecA excision (23). This type of event, previously reported in vivo in epidemic clones with or without antibiotic pressure (7), probably contributed to the large number of samples in our collection for which falsepositive results were recorded.…”

mentioning

confidence: 81%

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Evaluation of Three Molecular Assays for Rapid Identification of Methicillin-Resistant Staphylococcus aureus

François

Bento

Renzi³

et al. 2007

J Clin Microbiol

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One home-developed assay and two commercial assays for the rapid identification of methicillin-resistant Staphylococcus aureus (MRSA) were compared by use of a collection of clinical isolates displaying highly diverse genetic backgrounds. Our results suggest that users of orfX-staphylococcal cassette chromosome mec-based assays should repeatedly monitor the local epidemiology to minimize the risks of detection bias and the omission of emerging MRSA clones.

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supporting

confidence: 61%

mentioning

confidence: 81%

Evaluation of Three Molecular Assays for Rapid Identification of Methicillin-Resistant Staphylococcus aureus

François

Bento

Renzi³

et al. 2007

J Clin Microbiol

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“…In a recent study, the loss of the mecA gene in 36 (14.4%) of 250 methicillin-resistant Staphylococcus aureus isolates after 2 years of storage at Ϫ80°C was described (12). In the current evaluation, 29 MRSA strains gave discordant results, and a PCR for the mecA gene was performed on these isolates.…”

mentioning

confidence: 99%

Performance of MRSA ID, a New Chromogenic Medium for Detection of Methicillin-Resistant Staphylococcus aureus

et al. 2006

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MRSA ID was evaluated for its ability to identify methicillin-resistant Staphylococcus aureus. A well-defined collection of staphylococci was used (n ‫؍‬ 998). The sensitivity after 24 h was 96.4%, increasing to 98.8% after 48 h. The specificity was 98.2% after 24 h and decreased to 89.7% after 48 h.Methicillin-resistant Staphylococcus aureus (MRSA) has emerged worldwide as a nosocomial pathogen of major importance, and the incidence of infections caused by MRSA continues to increase (1,14). The recent emergence of community-acquired MRSA poses an additional challenge for microbiological laboratories to improve their screening strategies (6). Laboratory-based screening for MRSA colonization of patients and health care workers remains a cornerstone of infection control measures to limit the spread of this organism (5). Methods to detect MRSA in clinical samples ideally should have high sensitivity and specificity combined with a short time to reporting of the results. To identify S. aureus from contaminated samples more easily and reliably, selective media have been developed. Ideally, selective media achieve isolation of S. aureus and detection of methicillin resistance in one single step (4).The purpose of this study is to evaluate the in vitro sensitivity and specificity of a recently developed medium called MRSA ID for the identification of MRSA using a well-defined collection of strains.A collection consisting of 271 MRSA strains, 249 methicillin-susceptible Staphylococcus aureus (MSSA) strains, and 478 coagulase-negative staphylococci (CNS) was used. The collection was described previously (2, 3). In short, the MRSA isolates were collected in The Netherlands between 1989 and 1998 and are part of the MRSA strain collection of the National Institute of Public Health and Environmental Protection, Bilthoven, The Netherlands. Identification of strains as S. aureus and as being methicillin resistant was performed by duplex PCR for the mecA gene and the coagulase gene (11). Strains were selected on the basis of their different phage types (8, 13; J. A. Rost, unpublished data). The MSSA strains were isolated from cultures of blood collected between May 1996 and January 2005 from patients at the following five hospitals: St. Elisabeth Hospital and Tweesteden Hospital, Tilburg, The Netherlands; Pasteur Hospital, Oosterhout, The Netherlands; Tweesteden Hospital, Waalwijk, The Netherlands; and Amphia Hospital, Breda, The Netherlands. Only one isolate was included per patient per admission period. Isolates were identified by a latex agglutination test (Staphaurex Plus; Murex Diagnostics Ltd., Dartford, England), by the detection of free coagulase by the tube coagulase test with rabbit plasma, and by the detection of DNase (DNase agar; Oxoid Ltd., Basingstoke, England). If the results of these tests were discordant, an AccuProbe culture identification test (Gen-Probe, San Diego, Calif.) was performed according to the manufacturer's instructions, and this was considered the "gold standard." The blood culture isolates were...

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“…Testing of 60 stored MRSA isolates resulted in the confirmation of 58 as MRSA, while two were reclassified as MSSA. While these two discordant isolates might represent misidentifications by microbiologic techniques, it is possible that they might have lost the mecA gene during prolonged storage, as has been reported previously (19). The presence of mecA has been reported in several coagulasenegative staphylococcal (CoNS) species, including S. epidermidis (20,21), Staphylococcus haemolyticus, and Staphylococcus simulans (22).…”

Section: Discussionmentioning

confidence: 90%

Detection of Methicillin-Resistant Staphylococcus aureus by a Duplex Droplet Digital PCR Assay

et al. 2013

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bHealth care-associated infections with methicillin-resistant Staphylococcus aureus (MRSA) contribute to significant hospitalization costs. We report here a droplet digital PCR (ddPCR) assay, which is a next-generation emulsion-based endpoint PCR assay for high-precision MRSA analysis. Reference cultures of MRSA, methicillin-susceptible S. aureus (MSSA), and confounders were included as controls. Copan swabs were used to sample cultures and collect specimens for analysis from patients at a large teaching hospital. Swab extraction and cell lysis were accomplished using magnetic-driven agitation of silica beads. Quantitative PCR (qPCR) (Roche Light Cycler 480) and ddPCR (Bio-Rad QX100 droplet digital PCR system) assays were used to detect genes for the staphylococcal protein SA0140 (SA) and the methicillin resistance (mecA) gene employing standard TaqMan

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Loss of themecAGene during Storage of Methicillin-ResistantStaphylococcus aureusStrains

Cited by 50 publications

References 13 publications

Evaluation of Three Molecular Assays for Rapid Identification of Methicillin-Resistant Staphylococcus aureus

Evaluation of Three Molecular Assays for Rapid Identification of Methicillin-Resistant Staphylococcus aureus

Performance of MRSA ID, a New Chromogenic Medium for Detection of Methicillin-Resistant Staphylococcus aureus

Detection of Methicillin-Resistant Staphylococcus aureus by a Duplex Droplet Digital PCR Assay

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