Genotypic and phenotypic characterization of methicillin-resistant Staphylococcus aureus ( MRSA) isolated from milk of bovine mastitis.

The aim of this study was to evaluate the presence of methicillin-resistant Staphylococcus aureus ( MRSA) among a ( S. aureus) collection ( n = 430) isolated from milk of cows suffering from mastitis in Belgium and to compare their genotypic as well as phenotypic characteristics. Pulsed field gel electrophoresis ( PFGE) and PCR-based typing techniques ( MLST, spa, SCC mec, and agr typing) have been applied and supplemented by capsule serotyping, biofilm production quantification and antimicrobial susceptibility testing. Nineteen MRSA were isolated. Seven distinct ApaI PFGE patterns were observed. All isolates, except one, were identified as ST398 strains. Three spa types (t011, t567 and t108) and two SCC mec types ( IV and V) were identified. All isolates belonged to agr type I and capsule type 5 and were Panton-Valentine leukocidin ( PVL) negative. All isolates produced biofilm in TSB_glc, whereas the majority did not in milk serum. Twelve resistance patterns were observed, with almost two-thirds of the isolates being resistant to at least six antibiotics, including penicillin and tetracycline. Our study confirms that the emerging ST398 LA- MRSA clone has attained Belgian cattle. With regard to genotypic and phenotypic typing, the 19 MRSA isolated in this study form a homogenous group and do not differ much from one another, neither from what has been previously described. Significance and Impact of the Study This study confirms the presence of ST398 MRSA in milk from bovine mastitis in Belgium. Moreover, the isolated MRSA strains were described for genotypic and phenotypic characteristics potentially implicated in virulence. This study highlights that Belgian bovine could be a reservoir of MRSA for human. [ABSTRACT FROM AUTHOR]