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Prevalence of Panton-Valentine leukocidin genes in methicillin-resistant Staphylococcus aureus strains and susceptibility patterns

Abstract number: P1858

Pitart C., Álvarez M., Almela M., Mensa J., Martínez J.A., Soriano A., Puig de la Bellacasa J., Vila J., Jiménez de Anta M.T., Marco F.

Objectives: MRSA is an important cause of both nosocomial and community-acquired infections. Severe MRSA infections, including necrotising pneumonia, bacteraemia and skin and soft tissue infections (SSTIs) have been associated with the virulence factor Panton-Valentine leukocidin (PVL). The aim of this study was to investigate the presence of PVL genes, clonality and their susceptibility patterns in MRSA isolates collected from patients in our institution from October 2007 to December 2008.

Methods: All MRSA strains isolated during this period of time were screened for PVL genes. Genotype characterisation of PVL was made by co amplification of the genes lukS-PV and lukF-PV by PCR. Biochemical and antimicrobial susceptibility of isolates were performed by Phoenix® (Becton Dickinson, Franklin Lakes, NJ, USA). Glycopeptides, daptomycin and linezolid MICs were determined by Etest® (AB Biodisk, Solna, Sweden). All MRSA PVL positive isolates were genotyped by pulsed field gel electrophoresis (PFGE)after digestion with SmaI.

Results: 213 MRSA isolates were collected, 24 (11.3%) were PVL positive. Strains were isolated from cutaneous abscesses (7), ulcer infection (5), cellulitis (5), folliculitis (4), surgical site infection (2) and nasal swab (1). Ten different susceptibility patterns were found. Resistance only to penicillin and oxacillin was observed in 5 isolates. All isolates were susceptible to cotrimoxazole, rifampin, vancomycin, teicoplanin, daptomycin, fusidic acid and linezolid. MIC90 for vancomycin, teicoplanin, daptomycin and linezolid were 2, 2, 0.75 and 0.5 mcg/ml, respectively. Patients carrying PVL positive MRSA strains (24) were from Spain (16), USA (2), France (1), Italy (1), Cuba (1), Brazil (1), Ecuador (1) and Argentina (1). Among these strains, nine PFGE patterns were observed.

Conclusion: MRSA PVL strains are an increasing problem due to its involvement in SSTIs. In our institution these isolates represent 11.3% of MRSA strains. Recent marketed anti-staphylococci antibiotics such as daptomycin and linezolid demonstrated good activity against these particular MRSA isolates.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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