Evaluation of the newly modified AutoMicrobic system gram-positive susceptibility-MIC card for detection of methicillin-resistant Staphylococcus aureus.

AutoMicrobic system (Vitek Systems, Inc., Hazelwood, Mo.) gram-positive susceptibility-MIC (GPS-MIC) cards and GPS cards were compared for their ability to detect methicillin-resistant Staphylococcus aureus (MRSA) in two groups of isolates. MRSA isolates from the first group were detected at rates of 23 and 85%, and MRSA isolates from the second group were detected at rates of 95 and 88% for GPS and GPS-MIC cards, respectively. Detection of MRSA by the AutoMicrobic system lacks sensitivity and remains unsatisfactory unless accompanied by supplemental testing.