MOLECULAR TYPING OF STAPHYLOCOCCUS AUREUS STRAINS ISOLATED FROM MASTITIS BOVINE MILK IN ARGENTINA

ARCHAMBAULT M.; SREDNIK M. E.; GENTILINI E. R.; USONGO V.

SINGAPUR

Congreso; IUMS 2017; 2017

IUMS

Objectives: This study was conducted to characterize S. aureus isolates recovered from mammary quarter milk of mastitic cows from different dairy herds spread over four provinces in Argentina.Methods: A total of 229 S. aureus isolates were recovered from 829 mastitis bovine milk samples obtained from 21 farms giving a prevalence of isolation of 28.1 %. Eighty isolates were randomly selected from the 229 for further characterization.Strain relatedness was analysed by pulsed-field gel electrophoresis (PFGE) of total DNA restricted with Cfr9I enzyme using the protocol of Mulvey et al. (2001) with minor modifications. The resulting banding patterns were analyzed using the Bionumerics software version 6.6. Dendograms were generated from similarity matrixes calculated with the Dice coefficient, and patterns were clustered by the unweighted-pair group method with arithmetic averages using an optimization and tolerance of 1.5%. The definition of a PFGE cluster was based on a similarity cut-off of 80 %.Results: Restriction analysis followed by PFGE revealed 23 distinct pulsotypes at 80% similarity. Seven major types (A, B, N, P, S, T, U and V) accounted for 68.7 % of these isolates and 12 pulsotypes (A, B, F, G, J, K, M, N, P, S, T and U) occurred on more than one farm indicating genetic diversity within the farms (Fig. 1). Multilocus sequence typing (MLST) of a representative isolate from dominant types identified the sequence types 97,705, 746, 2102 and 2187 with ST 97 being the most predominant.Conclusion: In summary, our data demonstrate that S. aureus isolates from mastitis cases in Argentina were genetically diversesince several of the isolates belonged to pulsotypes that were widely distributed across multiple farms.This study was financed by the Secretaría de Ciencia y Técnica, Universidad de Buenos Aires (UBACyT) of Argentina (E. Gentilini, project BA313). Work in Canada was supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada (M. Archambault, RGPIN-191461).Disclosure of Interest: None DeclaredKeywords: bovine mastitis, molecular typing, Staphylococcus aureus