Comparison of several methods to determine methicillin-resistance in Staphylococcus aureus with focus on borderline strains.
We compared the performance of several phenotypic tests to detect methicillin-resistant Staphylococcus aureus, with special focus on borderline strains. The reliability of the agar screen oxacillin and BBL Crystal tests was asserted for all methicillin-susceptible (n = 25), -resistant (n = 29) and borderline beta-lactamase-hyperproducer (n = 10) strains. Whereas these tests failed to detect 4 of 5 rare borderline strains containing few cells with high-level methicillin resistance (i.e., a frequency of 10(-7)-10(-8)), a "two-temperature" disk diffusion method, performed simultaneously at 35 and 42 degrees C, detected all of such strains.
Nicola
F
F
Department of Microbiology, Centro de Educación Médica e Investigaciones Clínicas, Billinghurst 2447, (1425), Buenos Aires, Argentina.
Bantar
C
C
Canigia
L F
LF
Relloso
S
S
Bianchini
H
H
Smayevsky
J
J
D000667:Ampicillin / Q000494:pharmacology; D015169:Colony Count, Microbial; D006801:Humans; D016106:Methicillin Resistance / Q000235:genetics*; D010068:Oxacillin / Q000494:pharmacology; D010406:Penicillins / Q000494:pharmacology; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D012965:Sodium Chloride / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics
D010406:Penicillins; D012965:Sodium Chloride; D000667:Ampicillin; D010068:Oxacillin