Comparison of the Vitek Gram-Positive Susceptibility 106 card and the MRSA-screen latex agglutination test for determining oxacillin resistance in clinical bloodstream isolates of Staphylococcus aureus.
The Vitek automated susceptibility testing system with a modified Gram-Positive Susceptibility (GPS) 106 Card (bioMerieux Vitek, Inc., Hazelwood, Mo.) and a rapid slide latex agglutination test (MRSA-Screen; Denka Seiken Co., Ltd., Tokyo, Japan) were evaluated for their ability to detect oxacillin resistance in Staphylococcus aureus. The oxacillin-salt agar screen (OS) test, the reference broth microdilution method, and the detection of the mecA gene by PCR were compared with the commercial products. A total of 200 contemporary (1999) bloodstream infection isolates were collected from the SENTRY Antimicrobial Surveillance Program, representing diverse geographic areas throughout the world. Among the 99 mecA-positive isolates, 3 isolates were found negative by the MRSA-Screen. Another two isolates did not grow on OS plates and had MICs of 0.5 and 2 microg/ml with the Vitek GPS card. All 101 mecA-negative isolates were also found negative by the MRSA-Screen and were categorized as susceptible by the GPS card. Overall, the MRSA-Screen, GPS card, and OS test had sensitivities of 96.9, 98.0, and 98.0% and specificities of 100.0, 100.0, and 98.0%, respectively. MRSA-Screen was a rapid (</=15 min) and simple test to perform, and the GPS card provided results in <8 h. Both methods were sensitive and specific for detecting staphylococcal oxacillin resistance in the clinical microbiology laboratory.
Yamazumi
T
T
Medical Microbiology Division, Department of Pathology, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.
Marshall
S A
SA
Wilke
W W
WW
Diekema
D J
DJ
Pfaller
M A
MA
Jones
R N
RN
D016470:Bacteremia / Q000382:microbiology; D004352:Drug Resistance, Microbial; D006801:Humans; D007841:Latex Fixation Tests; D016106:Methicillin Resistance / Q000235:genetics; D008826:Microbial Sensitivity Tests / Q000379:methods*; D010068:Oxacillin / Q000494:pharmacology*; D010403:Penicillin Resistance; D010406:Penicillins / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification
D010406:Penicillins; D010068:Oxacillin