Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus, Rural Southwestern Alaska

摘要

USA300 is the dominant strain responsible for commu-nity-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) infections in most of the United States. We examined isolates from outbreaks of MRSA skin infections in rural southwestern Alaska in 1996 and 2000 (retrospec-tive collection) and from the hospital serving this region in 2004–2006 (prospective collection). Among 36 retrospec-tive collection isolates, 92% carried Panton-Valentine leuko-cidin (PVL) genes; all carried staphylococcal chromosomal cassette mec (SCCmec) type IV. None belonged to clonal complex (CC) 8, the CC associated with USA300; 57% were sequence type (ST) 1, and 26% were ST30; 61% were clin-damycin resistant. In the prospective collection, 42 isolates were PVL+ and carried SCCmec type IV; 83.3% were ST1, 9.5% were ST30, and 7.1% were ST8. Among 120 prospec-tive isolates, 57.5% were clindamycin resistant. CA-MRSA epidemiology in southwestern Alaska differs from that in the lower 48 states; ST8 strains were rarely identifi ed and clin-damycin resistance was common