Incidence of clinical and sub-clinical bovine mastitis caused by Staphylococcus aureus in Proddatur region of Andhra Pradesh

Abstract

Staphylococcal mastitis is one of the commonest infection associated with dairy animals, mostly prevails in sub-clinical form and once left unidentified, usually flares up with clinical mastitis resulting in huge economic losses to the dairy owners. Therefore, the present study was undertaken to know the incidence of clinical and sub-clinical mastitis caused by Staphylococcus aureus in bovines in the Proddatur region of Andhra Pradesh by means of conventional and molecular methods. A total of 61 clinical mastitis milk samples were collected and 105 milk samples were screened for the presence of sub-clinical mastitis by California mastitis test (CMT). The clinical samples and the samples positive for sub-clinical infection were then subjected for specific culture and morphological identification by gram’s staining. The positive isolates were further confirmed for Staphylococcus genus and S. aureus by PCR targeting the 16S rRNA and nuc gene respectively. The overall incidence of Staphylococcus Sp and S. aureus in bovine mastitis was found to be 89% and 54% respectively in clinical mastitis and 71% and 50% in sub-clinical mastitis as confirmed by PCR. These findings clearly indicate the prevalence of S. aureus infection in bovine mastitis in this specific region and suggest the need for the routine screening of dairy herds for S. aureus associated mastitis infection, use of better management and animal husbandry practices for the prevention and early cure of bovine mastitis.