Prevalence and Antibiotic Resistance of Staphylococcus aureus and Risk Factors for Bovine Subclinical Mastitis in District Kasur, Punjab, Pakistan

The present study was designed to determine the prevalence and possible risk factors of subclinical mastitis along with antibiotic resistance of one of the causative agent of bovine mastitis, Staphylococcus aureus. Ninety milk samples were collected from cows and buffaloes kept at different localities in district Kasur, Punjab, Pakistan. The possible risk factors inquired from farmers were animal type, breeds, urbanicity, age (years), teat washing, bedding area, lactating stage and previous exposure of mastitis. Initially surf field mastitis test (SFMT) was applied for screening subclinical mastitis followed by bacteriological techniques on positive milk samples for confirmatory isolation of Staph. aureus as a bovine mastitis causing agent. These Staph. aureus isolates were further tested for antibiotic susceptibility. Epidemiological data was analyzed by chi-square methods at 95% confidence interval. The overall prevalence of subclinical mastitis as a result of surf field mastitis test was 42.2%. The prevalence of disease was higher in cows (54.5%) than in buffalo (22.9%). Based on chi-square and P-value the prevalence of mastitis was significantly (P<0.05) associated with animal type, urbanicity, age of animal and previous exposure of mastitis. There was no association of the prevalence of bovine subclinical mastitis with breed, teat washing, bedding area and lactating stage. Out of 38 positive milk samples, 13 (34.2%) were positive for Staph. aureus. All isolates of Staph. aureus were resistant for ten different antibiotics. It was concluded that multi-drug resistant strains of Staph. aureus were major causative agent of bovine subclinical mastitis and there were multiple risk factors associated with incidence of mastitis.