Staphylococcus aureus biotypes isolated from raw milk of cows with subclinical mastitis

Abstract

The present study aimed to determine the origin of thirty enterotoxin producing and non-producing strains of Staphylococcus aureus isolated from milk of cows with subclinical mastitis. For this, strains were screened by a biotyping method proposed by Devriese, basing on their production of staphylokinase (K), beta - hemolysis (β), coagulation of bovine plasma (CPB) and growth on crystal violet (CV). The 30 strains of S. aureus were grouped into nine biotypes and four of them were host-specific biotypes, as follows: aviary (05), bovine (02), human (01) and sheep (01). Twenty-one strains belonged to five non-host-specific biotypes with the following biochemical characteristics: K - β +; CPB -; CV: A (06), K-β +; CPB-; CV: C (05), K- β +; CPB-; CV: E (04), K- β -; CPB-; CV: C (03) and K- β -;-CPB; CV: E (03); strains grouped into some of these groups could be isolated from human, bovine, and bird. The non-host-specific was the most frequent biotype among enterotoxin producing and non-producing strains. The predominance of non-host-specific biotypes points to the occurrence of a deficient animal management with risks to public health. Keywords: Staphylococcus aureus, biotyping, enterotoxin, mastitis, cow milk.