Prevalence of S. aureus and E. coli causing subclinical Mastitis in goat with their antibiotic resistance pattern and associated risk factors

Abstract

An investigation was carried out to evaluate the status of the caprine clinical and subclinical mastitis in Chittagong Metropolitan Area. A total of 61 lactating goats were sampled during the period of January 2015 to June 2015 from Shahidul Alam Quadary Teaching Veterinary Hospital (SAQTVH) of Chittagong Veterinary and Animal Sciences University (CVASU). Clinical diagnosis of mastitis (clinical and subclinical) in goats was based on the California Mastitis Test (CMT). The prevalence of subclinical mastitis was estimated at nearly 64% (39 positive samples). One of the sampled animals showed clinical signs of mastitis. Milk samples were further analyzed for the isolation and identification of bacterial agents that were previously found associated with caprine subclinical mastitis. 28 (71.79% among 39 positive samples) samples were culture positive to Staphylococcus aureus and 14 (35.90% among 39 positive samples) were culture positive to E. coli. Among all tested samples, the overall prevalence of subclinical mastitis caused by S. aureus was 46% and E. coli 23%. 10 antibiotic disks were used to evaluate the antibiotic sensitivity of the isolated bacteria. The most sensitive antibiotics against Staphylococcus aureus were amoxicillin (82.15%), trimethoprim (64.29%), doxycycline (100%), ciprofloxacin (67.86%). The most sensitive antibiotics against E. coli were colistin sulphate (85.71%), doxycycline (100%), gentamycin (100%), and ciprofloxacin (92.86%). In addition, suspected risk factors such as age of animal, parity, length of lactation period, type of farming system and type of housing floor etc. for subclinical mastitis were also analyzed with advanced statistical tools. The findings of the present study will facilitate accuracy in public service from the Clinical Pathology Laboratory, CVASU through proper diagnosis followed by treatment.