Molecular epidemiology of MRSA in the Brazilian primary health care system

OBJECTIF: Evaluer l’epidemiologie moleculaire et georeferencer le Staphylococcus aureus isole de plaies et de narines de patients vus dans les unites sanitaires de base (BHU) d'une ville bresilienne. METHODES: Etude observationnelle transversale realisee de 2010 a 2013. Au total, 119 souches de S. aureus isolees de plaies et de narines de 88 patients ont ete etudiees. Les isolats ont ete caracterises par l'identification de genes de virulence codant pour les enterotoxines AE, les hemolysines α, β et δ, les exfoliatines A, B et D, la production de biofilm, la leucocidine de Panton-Valentine et la toxine 1 du syndrome de choc toxique, et par typage par electrophorese sur gel en champ pulse (PFGE), sequence multilocus et spa. RESULTATS: Dix-huit SARM (6 de type II SCCmec et 12 de type IV SCCmec) et 101 (85%) SASM ont ete identifies. Le typage PFGE a resulte a l'obtention de huit grappes, dont STs 1, 5, 8, 30, 188, 1176 et 1635 et le type spa t002 etant les types predominants parmi les SASM. Les 18 SARM appartenaient aux STs 5, 8 et 1176 et aux types de spa t002 et t062. METHODS: Observational, cross-sectional study conducted from 2010 to 2013. A total of 119 S. aureus strains isolated from the wounds and nares of 88 patients were studied. The isolates were characterised by identifying virulence genes encoding enterotoxins A-E, haemolysins α, β and δ, exfoliatins A, B and D, biofilm production, Panton-Valentine Leukocidin and toxic shock syndrome toxin 1, and by pulsed-field gel electrophoresis (PFGE), multilocus sequence and spa typing. RESULTS: Eighteen methicillin-resistant Staphylococcus aureus (MRSA) (6 SCCmec type II and 12 SCCmec type IV) and 101 (85%) MSSA were identified. PFGE typing resulted in the formation of eight clusters, with STs 1, 5, 8, 30, 188, 1176 and 1635 and spa type t002 being the predominant types among MSSA. The 18 MRSA belonged to STs 5, 8 and 1176 and spa types t002 and t062. CONCLUSION: The results demonstrate widespread dissemination of MSSA and MRSA clones carrying haemolysin, biofilm and toxin genes. Kernel density estimation revealed the highest density of S. aureus in the 4, 5 and 8 BHUs.