Mueller-Hinton agar is superior to PDM blood agar for detection of methicillin-resistant Staphylococcus aureus.
Clin Microbiol Infect 2003;
9:61-4. [PMID:
12691545 DOI:
10.1046/j.1469-0691.2003.00462.x]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aim of this study was to compare the expression of oxacillin resistance in methicillin-resistant Staphylococcus aureus (MRSA) on Paper Disc Method agar supplemented with 5% defibrinated blood (PDM blood agar) and Mueller-Hinton agar supplemented with 2% NaCl (MH NaCl agar) using different susceptibility tests. Fifty mecA-containing isolates of S. aureus, exhibiting 46 different pulsed-field gel electrophoresis patterns, were comparatively tested using the E test, the single disk diffusion test, and the multipoint inoculation technique, under various culture conditions. The E test incubated at 35 degrees C for 24 h (breakpoint of resistance > or = 2.0 mg/L) detected 94% of the isolates on MH NaCl agar, compared with 28% for PDM blood agar (P < 0.05). The disk diffusion test (breakpoint < 10 mm in diameter) under these incubation conditions detected resistance in 100% of the isolates on MH NaCl agar and in 80% of the isolates on PDM blood agar (P < 0.05). The multipoint technique (breakpoint > or = 1 mg/L), applied at 35 degrees C for 24 h, detected 100% on MH NaCl agar and 46% on PDM blood agar (P < 0.05). Irrespective of the method of susceptibility testing evaluated, MH NaCl agar was superior to PDM blood agar for the detection of oxacillin resistance in mecA-containing S. aureus.
Collapse