Evaluation of commercial selective agars in screening for methicillin-resistant Staphylococcus aureus.
To evaluate methicillin-resistant S. aureus (MRSA) detection methods, we compared (a) mannitol salt agar with cefoxitin (MSA-FX), (b) MRSASelect agar (Bio-Rad), (c) MRSA ID (bioMerieuex), and (d) CHROMagar MRSA (BD Diagnostics) as selective media for culturing nasal swab specimens collected from intensive care unit (ICU) patients and healthcare personnel. A total of 99 (17.1%) cases of MRSA were recovered from 578 specimens. Four (5.5%) cases were identified from healthcare personnel and 95 (18.8%) were from ICU patients. The sensitivity of MSA-FX, MRSASelect, MRSA ID, and CHROMagar MRSA was 83.8, 87.9, 80.8, and 84.8% after 18 hr; 92.9, 94.9, 90.9, and 91.9% after 24 hr; and 96.0, 100, 99.0, and 99.0% after 48 hr, respectively. The specificity of MSA-FX, MRSASelect, MRSA ID, and CHROMagar MRSA was 97.7, 99.0, 98.7. and 99.8% after 18 hr; 97.1, 98.5, 98.1, and 99.5% after 24 hr; and 95.2, 97.7, 97.9, and 99.0% after 48 hr, respectively. In conclusion, all four media showed good results after the 24 hr readings, but MRSA ID and CHROMagar MRSA media required readings at 48 hr due to increased sensitivity at this time point.
Yang
Hee-Young
HY
Department of Laboratory Medicine, Kosin University College of Medicine, Busan, Korea.
Suh
Jin-Tae
JT
Lee
Hee-Joo
HJ
D000362:Agar / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D015153:Blotting, Western; D002440:Cefoxitin / Q000494:pharmacology*; D002863:Chromogenic Compounds / Q000494:pharmacology*; D006282:Health Personnel; D006801:Humans; D007362:Intensive Care Units; D008353:Mannitol / Q000494:pharmacology*; D055624:Methicillin-Resistant Staphylococcus aureus; D009297:Nasal Mucosa / Q000382:microbiology*; D046915:Penicillin-Binding Proteins; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002863:Chromogenic Compounds; D046915:Penicillin-Binding Proteins; D012333:RNA, Messenger; C487789:mecA protein, Staphylococcus aureus; D008353:Mannitol; D002440:Cefoxitin; D000362:Agar