Abstract
A clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA) with intermediate resistance to vancomycin (minimal inhibitory concentration [MIC] of 4 μg/ml) was isolated in 2006 from a surgical wound of a patient hospitalized at the orthopedics ward of Hospital de São Marcos - Braga, in the town of Braga. A combination of molecular typing methods, including pulsed-field gel electrophoresis (PFGE), spa typing, multilocus sequence typing, and staphylococcal chromosomal cassette mec typing, identified the vancomycin intermediate-resistant S. aureus VISA-BRAGA as a derivative of the epidemic MRSA (EMRSA)-15 clone, which has been isolated with increasing frequency from several Portuguese hospitals recently. Compared to another EMRSA-15 isolate with the same genetic background (including PFGE subtype) the VISA-BRAGA isolate exhibited relatively high oxacillin MIC, slow growth, loss of hemolytic activity, and increased resistance to vancomycin and to daptomycin although neither of these two antibiotics was used in therapy. The VISA-BRAGA isolate described here appears to represent the first S. aureus with decreased susceptibility to vancomycin identified in a Portuguese hospital.
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