Determination of antibiotic resistance profiles of Bacillus cereus from subclinical mastitis of cattle in İzmir province

Mastitis causes significant economic losses in the dairy industry. In Türkiye, an estimated annual economic loss of 41.5 million TL is attributed to mastitis. Environmental and milking factors, alongside microbial factors, play a role in the development of mastitis. Various microorganisms, primarily bacteria, cause mastitis. This study aimed to determine the presence of Bacillus cereus and their antimicrobial susceptibilities in milk samples from subclinically infected cows in Izmir province. Milk samples from 400 dairy cows in Izmir province with subclinical mastitis were brought to the Bornova Veterinary Control Institute Bacteriology Laboratory and cultured on Columbia Agar supplemented with 5% sheep blood under cold chain conditions. Gram-positive bacilli colonies were purified and identified using the BCL prepared diagnostic kit on the VITEK 2 (bioMérieux) device. Five B. cereus (1.25 %) were isolated and identified from 400 subclinical mastitis milk samples by VITEK and PCR. The isolates were sensitive to gentamicin, chloramphenicol and tetracycline at the rates of 100 %. All of the isolates were resistant to amoxicillin clavulanic acid. Three of the isolates (60 %) were resistant against trimethoprim-sulfamethoxazole. The results suggest that Bacillus cereus may be responsible for subclinical mastitis cases in cattle in terms of public health, and that specidic treatment should be administered considering the antimicrobial susceptibility data obtained in our study.