Prediction of mecA-positive coagulase-negative staphylococci: assessment of different phenotypic methods, breakpoints, culture media and culture conditions.
Sensitivity for the detection of mecA-positive coagulase-negative staphylococci (CNS) was evaluated for different breakpoints of resistance for oxacillin using three different susceptibility tests, either on Mueller-Hinton agar supplemented with 2% NaCl (MH-NaCl agar) or on paper disc method agar supplemented with 5% defibrinated blood (PDM-blood agar). The Etest, multipoint inoculation test and disc diffusion test showed comparable sensitivity (0.96, 0.96 and 0.95, respectively) using an oxacillin breakpoint of > or = 0.5 mg/L or < or = 17 mm for the disc test, after incubation at 35 degrees C for 24 h on MH-NaCl agar. The sensitivity decreased for breakpoints > or = 1 mg/L and when PDM-blood agar was used instead of MH-NaCl agar.
Monsen
Tor
T
Department of Clinical Bacteriology, University Hospital of Umeå, Sweden. tor.monsen@climi.umu.se
Abd
Hadi
H
Leonardsson
Kjell
K
Edebro
Helén
H
Wiström
Johan
J
D001426:Bacterial Proteins; D001431:Bacteriological Techniques / Q000379:methods; D002352:Carrier Proteins / Q000235:genetics* / Q000302:isolation & purification; D003030:Coagulase / Q000235:genetics* / Q000302:isolation & purification; D003470:Culture Media / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006602:Hexosyltransferases; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000706:statistics & numerical data; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics* / Q000302:isolation & purification; D010068:Oxacillin / Q000494:pharmacology; D046915:Penicillin-Binding Proteins; D010406:Penicillins / Q000494:pharmacology; D010458:Peptidyl Transferases; D010641:Phenotype; D013210:Staphylococcus / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification
D001426:Bacterial Proteins; D002352:Carrier Proteins; D003030:Coagulase; D003470:Culture Media; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase; D010068:Oxacillin