Molecular and phenotypic characteristics of methicillin-resistant and vancomycin-intermediate Staphylococcus aureus isolates from patients with septic arthritis

Staphylococcus aureus is one of the most common pathogens in community- and hospital-associated infections and frequently causes severe and intractable infections in osteoarticular tissues. S. aureus isolates that are resistant to methicillin (meticillin) (MRSA isolates) and intermediately resistant to vancomycin (VISA isolates) have emerged. In this report, we described two patients, one female and one male, diagnosed with septic arthritis due to S. aureus infections. A total of 13 MRSA isolates were obtained from these two patients. All but one isolate belonged to the VISA group. All seven isolates from the female patient were determined to be community associated, multilocus sequence type (MLST) 59, and staphylococcal cassette chromosome mecA (SCCmec) type IV; had direct repeat units (DRUs) of nine repeats; were spa type t437; and were susceptible to sulfa and quinolone antibiotics. The other six isolates, from the male patient, were determined to be hospital associated, MLST 239, and SCCmec type III; had DRUs of 14 repeats; were spa type t037; and were resistant to sulfa and quinolone antibiotics. All 13 MRSA isolates were in agr group I, were pvl negative, and showed no evidence of any association between vancomycin resistance and autolysis.