Cultural, biochemical and haemolytic properties of staphylococcus aureus isolated from cases of subclinical mastitis in cattle

In the present study 38 Staphylococcus aureus isolates from subclinical mastitis cases in Holstein-Friesian (H-F) crossbred and Rathi (a native breed) cattle were characterized on the basis of their cultural, biochemical and haemolytic properties after confirmation by 23S r RNA based genotyping. The overall incidence of subclinical mastitis was 44.70 % with higher incidence (51.61 %) in H-F crossbred cattle than in Rathi cattle (40.74 %). Among the cultural and biochemical properties, 35 out of 38 isolates produced golden yellow colonies and three isolates produced white colonies. In the sugar fermentation reactions using 11 different sugars, variations were observed in the results. Thirty five isolates produced coagulase and the overall strongest coagulation reaction was recorded with plasma from human followed by horse, cattle, rabbit, sheep, camel, goat, dog, buffalo and chicken. Thirty two isolates were haemolytic while six were non-haemolytic. All the isolates produced α-toxin of high titres (1:2560 and 1:5120) and β-toxin was produced by 34 isolates with lower titres (1:5 to 1: 160). None of the isolates produced delta toxin. In conclusion, incidence of subclinical mastitis was more in H-F crossbred cattle than in Rathi cattle. Not all the isolates were pigmented, coagulase producer and hemolytic.