Successful Multiresistant Community-Associated Methicillin-Resistant Staphylococcus aureus Lineage from Taipei, Taiwan, That Carries Either the Novel Staphylococcal Chromosome Cassette mec (SCC mec ) Type V T or SCC mec Type IV

Abstract

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) isolates carry the methicillin resistance gene ( mecA ) on a horizontally transferred genetic element called the staphylococcal chromosome cassette mec (SCC mec ). Community-acquired MRSA (CAMRSA) isolates usually carry SCC mec type IV. We previously reported that 76% of 17 CAMRSA isolates (multilocus sequence type 59) obtained from pediatric patients with skin and soft tissue infections (SSTI) from Taipei did not carry SCC mec types I to IV. We used DNA sequence analysis to determine that the element harbored by these nontypeable isolates is a novel subtype of SCC mec V called SCC mec V T. It contains a ccrC recombinase gene variant ( ccrC2 ) and mec complex C2. One SSTI isolate contained molecular features of SCC mec IV but also contained ccrC2 (a feature of SCC mec V T ), suggesting that it may harbor a composite SCC mec element. The genes lukS-PV and lukF-PV encoding the Panton-Valentine leukocidin (PVL) were present in all CAMRSA SSTI isolates whether they contained SCC mec type IV or V T . SCC mec V T was also present in 5 of 34 (14.7%) CAMRSA colonization isolates collected from healthy children from Taipei who lacked MRSA risk factors. Four (80%) of the these isolates contained lukS-PV and lukF-PV , as did 1 of 27 (3.7%) SCC mec IV-containing colonization isolates. A total of 63% (10 of 16) of the SSTI isolates and 61.7% (21 of 34) of the colonization isolates tested were resistant to at least four classes of non-β-lactam antimicrobials. SCC mec V T is a novel SCC mec variant that is found in multiply resistant CAMRSA strains with sequence type 59 in Taipei in association with the PVL leukotoxin genes.