1. Panton-Valentine Leukocidin (PVL) is a toxin that destroys white blood cells and is a virulence factor in some strains of Staphylococcus aureus. PVL occurs in fewer than 2% of clinical isolates of S. aureus whether meticillin sensitive (MSSA) or resistant (MRSA). Interest in PVL related disease in the UK has emerged because community outbreaks of MRSA, most of which are PVL positive. Although rare at present, continued vigilance regarding epidemiology and antimicrobial sensitivity of these isolates is required. Antimicrobial sensitivity in isolates of Panton-Valentine Leukocidin positive Staphylococcus aureus in Wales Backx M, Howe RA, Wootton M NPHS Microbiology, University Hospital of Wales, Cardiff, UK. Introduction Objectives This study was performed to assess the antimicrobial susceptibility profiles of PVL positive S. aureus isolates from across Wales. 61 isolates were found to be PVL positive and were analysed using the automated Phoenix system. In addition isolates were analysed for trimethoprim and minocycline susceptibility using E testing ®. Isolates found to be erythromycin resistant and clindamycin sensitive were tested for inducible clindamycin resistance using D testing. MethodsResults Antimicrobial susceptibility of isolates was compared to that of data gathered by the Welsh Antimicrobial Surveillance Unit over the year 2007. Erythromycin and ciprofloxacin sensitivity was higher in PVL positive MRSA versus PVL negative MRSA isolates as summarised in table 1. Key: Gent = gentamicin, Pen = penicillin G, Oxa = oxacillin, Trim-e = trimethorpim e-test, Teic = teicoplanin, Vanc = vancomycin, Clinda = clindamycin, Clinda-D = clindamycin D-test, Ery = erythromycin, Chlor = chloramphenicol, Fus = fucidic acid, Lin = linezolid, Nitro = nitrofurantoin, Cip = ciprofloxacin, Rif = rifampicin, Tet = tetracycline, Mino-e = minocycline e-test Conclusions Table 1 PVL and Welsh Antimicrobial Surveillance Data Antimicrobial sensitivity % ErythromycinCiprofloxacin Blood Cultures 2007 MSSA MRSA 90.9 24.8 Not Available 1.7 Swabs 2007 MSSA MRSA 90.1 31.9 Not Available 4.6 PVL MSSA MRSA 80 61.3 96.7 90.3 All isolates were susceptible to linezolid, vancomycin, teicoplanin and rifampicin and overall over 90% of isolates were sensitive to clindamycin. For suspected PVL disease, rifampicin with a second agent such as doxycycline, fucidic acid, trimethoprim or ciprofloxacin would be appropriate for empiric therapy. In severe PVL disease, linezolid in combination with clindamycin would be appropriate for empiric therapy. Ciprofloxacin and possibly erythromycin sensitivity in MRSA isolates appears to be a surrogate marker for PVL positivity. Conclusions Methods Between January 2007 and July 2008 199 isolates were sent to the University Hospital of Wales for PVL testing PVL genes lukF/lukS were detected using PCR with specific primers. Results The antimicrobial susceptibility of the isolates, depicted as the percentage of isolates sensitive to a given antibiotic, is summarised in figure 1. The HPA recommends ciprofloxacin sensitive MRSA isolates be sent for PVL testing and our study may therefore over represent these and not reflect community trends. Contact details: Email: matthijs.backx@cardiffandvale.wales.nhs.uk