Abstract
Objective: The purpose of this study is to find out the epidemiological phenomenon of mastitis in dairy cattle and identify the most common pathogens, Escherichia coli and Staphylococcus aureus, in clinical and subclinical mastitis in dairy cattle with their antibiotic profiles of several selected areas of Tangail District, Bangladesh. Materials and Methods: A total of 250 lactating cows were examined in the study area, 28 of which had clinical mastitis, determined by the physical characteristics of milk and udder. Meanwhile, 205 suspected lactating cows were tested for subclinical mastitis using the California Mastitis Test, and 54 were positive. Staphylococcus aureus and E. coli were isolated and identified by conventional techniques such as bacterial culture, Gram stain, and biochemical test. Antimicrobial susceptibility testing was performed by the disk diffusion method. Results: This study reported clinical and subclinical mastitis prevalence as 11.20% (28/250) and 26.34% (54/205), respectively. Out of 72 milk samples, 26 (36.11%) were positive for S. aureus, 15 (20.83%) for E. coli, 22 (30.56%) for mixed organisms, and 9 (12.5%) were unidentified organisms. This study also showed that Friesian cross-breeds cows, the cows with parity 1 to 3, early stage of lactation, and high-yielding dairy cows were significantly more susceptible to mastitis. Antibiogram studies revealed that 85.42% of S. aureus and 64.86% of E. coli were multiple drug resistant (MDR). The S. aureus was found to be highly sensitive to gentamicin (CN) (95.83%) and ciprofloxacin (CIP) (54.17%) and resistant to ceftriaxone (CRO) (75.0%) and oxacillin (68.75%). On the other hand, the E. coli was highly sensitive to CN (97.30%) and CIP (75.68%) and resistant to streptomycin, CRO, and oxacillin at 56.76%. Conclusion: The results of this study may help governments and livestock agencies to ensure that registered veterinarians only prescribe dairy cows and to make farmers aware of mastitis. This will help reduce MDR and prevent threats to human health from consuming milk. Therefore, the rational use of CN and CIP is recommended to effectively resolve most disease cases in dairy cattle.

Key words: Bovine mastitis; prevalence; antibiogram; S. aureus and E. coli