title: A selective broth enrichment combined with real-time nuc-mecA-PCR in the exclusion of MRSA.
abstract: We analyzed the performance of a selective enrichment broth combined with Taqman-based real-time duplex nuc-mecA-PCR to expedite the screening of methicillin-resistant Staphylococcus aureus (MRSA). We found the broth to be able to select MRSA strains (oxacillin MIC range 4-256 microg/ml) from MSSA strains. A total of 31 MRSA strains were found from 1250 clinical samples screened. The nuc-mecA-PCR was positive from all enrichment broths containing MRSA. From the remaining 1219 samples negative for MRSA on culture/subculture, 138 samples were nuc+/mecA+ in PCR. The sensitivity of the test was 93.5%, specificity 88.6%, positive predictive value 17.3%, and negative predictive value 99.8% as compared to culture. Thus, with this method, the negative MRSA results can be reliably reported within 24-48 h from sampling. The method is a practical additional alternative to those already described for the same purpose.
authors.affiliation: Division of Clinical Microbiology, HUSLAB, Helsinki University Hospital, Helsinki, Finland.
authors.forename: Tanja
authors.initials: T
authors.lastname: Pasanen
authors.forename: Maija
authors.initials: M
authors.lastname: Korkeila
authors.forename: Sointu
authors.initials: S
authors.lastname: Mero
authors.forename: Eveliina
authors.initials: E
authors.lastname: Tarkka
authors.forename: Heli
authors.initials: H
authors.lastname: Piiparinen
authors.forename: Jaana
authors.initials: J
authors.lastname: Vuopio-Varkila
authors.forename: Martti
authors.initials: M
authors.lastname: Vaara
authors.forename: Päivi
authors.initials: P
authors.lastname: Tissari
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D018929:Cell Culture Techniques / Q000379:methods*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*; D008836:Micrococcal Nuclease / Q000737:chemistry / Q000235:genetics*; D046915:Penicillin-Binding Proteins; D016133:Polymerase Chain Reaction / Q000379:methods*; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus; C074002:nuc protein, staphylococcus; D008836:Micrococcal Nuclease