Coagulase gene polymorphism of Staphylococcus aureus isolates from dairy cattle in different geographical areas

The objectives of this study were to investigate the coagulase gene polymor phism of Staphylococcus aureus isolates obtained from bovine mastitic milk and to determine the resistance of predominant and rare coagulase genotypes to bovine blood neutrophil bactericidal activities. A total of 453 isolate s were collected from four countries: the Czech Republic, France, Korea and the United States. The isolates were subtyped into 40 types by restriction fragment length polymorphism (RFLP) of the coagulase gene. Twenty-three st rains from predominant and rare genotypes were evaluated for their ability to resist neutrophil bactericidal activities. There were significant (P < 0 .01) differences in the average percent neutrophil killing of the predomina nt (16.7 %) and rare (39.7 %) genotypes when bacteria were opsonized with a ntiserum. The results indicate that the profiles of coagulase genotype diff er among geographic locations, and only a few genotypes prevail in each loc ation. In addition, the predominant genotypes were more resistant to neutro phil bactericidal activities than rare genotypes.