Polyclonal multiply antibiotic-resistant methicillin-resistant Staphylococcus aureus with Panton-Valentine leucocidin...

Community-associated methicillin-resistant Staphylococcus aureus (MRSA) including those encoding Panton-Valentine leucocidin (PVL) are often described as more susceptible to a range of antibiotics than their hospital-associated counterparts. Recent scattered reports of the emergence of multiresistant PVL-MRSA have highlighted the potential for resistance to emerge. Here we detail polyclonal multiply antibiotic-resistant PVL-MRSA occurring in England.

PVL-MRSA from community-based and hospitalized patients located across England were identified by PCR. Isolates were characterized via MIC determinations, toxin gene profiling, PFGE, SCCmec, spa and agr typing. Multilocus sequence typing (MLST) was performed on selected isolates. Patient demographic and available disease data were retained for analysis.

Seventy-six PVL-MRSA isolates resistant to three further classes of antibiotic were identified between 2005 and 2008 from centres in each of the Health Protection Agency's geographic regions in England. Patient demographics were typical for PVL-MRSA, and some travel associations were identified along with clonal spread. One instance of familial transmission in the community was detected. PVL-MRSA belonging to MLST clonal complex (CC) 1 (sequence type 772) were consistently highly resistant; multiply antibiotic-resistant representatives of CCs 5, 8, 22, 59 and 80 were also identified. Ciprofloxacin resistance was common amongst the study isolates (51 of 76 isolates).

Genetically diverse multiply antibiotic-resistant PVL-MRSA were identified, and included representatives of a recently emerged multiresistant clone (dubbed the Bengal Bay clone). Risk factors and disease presentations were typical for PVL-MRSA infections. This work highlights the diminishing utility of ciprofloxacin susceptibility for putative identification of PVL-MRSA.