Prevalence of clinical and subclinical mastitis, antibiotic resistance and determination of minimum inhibitory concentration [MIC] in staphylococus aureus and Escherichia coli isolated from cases of Bovine mastitis

ABSTRACT

To examine the prevalence of clinical and subclinical bovine mastitis and determination of minimum inhibitory cocentration [MIC] in the original bacteria [such as staphylococus auteus [S. aureus] and Escherichia coli [E. coli] responsible for this disease. Three hundred thirty eight cows from 8 herds. Cross sectional study. Descriptive study. Samples were collected from 1352 quarters of 338 cows in eight farms at the morning milking. California mastitis test [CMT] was carried out on each sample. Isolation, identification of bacteria and determination of minimum inhibitory concentration [MIC] were carried out in the laboratory. The MIC and MBC of antibiotics [Chloramphenicol, Cephalexin, Amoxicillin, Ampicillin, Tetracycline, Streptomycin, Enrofloxacin, Gentamicin] were carried out against 200 bacterial isolates including 118 E. coli and 82 S. aureus isolated from bovine mastitis. Antimicrobial susceptibility testing showed that all the isolates were sensitive to Gentamicin and Enrofloxacin and resistant to Penicillin. The occurrence of clinical and subclinical mastitis were 6.80 and 67.45 percent in herds, respectively.While the MIC values higher than 100 microg/ml for 9 antibiotics [Chloramphenicol, Cephalexin, Amoxicillin, Ampicillin, Penecillin, Tetracycline, Streptomycin, Enrofloxacin, Gentamicin] against E.coli were 11.0, 0, 12.2, 20.7, 100, 22, 15.9, 0 and 0%, these values against S.aureus were!5.3,0, 30.3,0,100, 38.1,48.3, 0 and 0%, respectively. On the other hand, while, the MBC levels for these antibiotics against E.coli were 40.2, 19.5, 96.3,48.7, 100, 74.4, 29.3, 0 and 0% these values against S. aureus were 46.6, 13.5, 84.7, 100, 100, 100, 89, 0%, respectively