Abstract:
Staphylococcus aureus is recognized worldwide as one of the major agents of dairy cow
intra-mammary infections. This microorganism can express a wide spectrum of pathogenic factors
used to attach, colonize, invade and infect the host. The present study evaluated 120 isolates from
eight different countries that were genotyped by RS-PCR and investigated for 26 different virulence
factors to increase the knowledge on the circulating genetic lineages among the cow population with
mastitis. New genotypes were observed for South African strains while for all the other countries
new variants of existing genotypes were detected. For each country, a specific genotypic pattern was
found. Among the virulence factors, fmtB, cna, clfA and leucocidins genes were the most frequent.
The sea and sei genes were present in seven out of eight countries; seh showed high frequency in South American countries (Brazil, Colombia, Argentina), while sel was harboured especially in one
Mediterranean country (Tunisia). The etb, seb and see genes were not detected in any of the isolates,
while only two isolates were MRSA (Germany and Italy) confirming the low diffusion of methicillin
resistance microorganism among bovine mastitis isolates. This work demonstrated the wide variety
of S. aureus genotypes found in dairy cattle worldwide. This condition suggests that considering the
region of interest might help to formulate strategies for reducing the infection spreading.
