The Susceptibility to Antibiotics of Some Bacterial Strains Isolated from Cow Milk with Mastitis

George Cosmin NADAS, Nicodim FIT, Cosmina BOUARI, Flore CHIRILA, Sorin RAPUNTEAN, Vasile RUS


Recent increased resistance to antibiotics of bacterial strains isolated from cow milk with mastitis represented a strong motivation for a study that would indicate the most efficient antibiotic for treatment. This study evaluated a total number of 31 samples collected from cows suffering from mastitis. Each sample was initially processed by the smear preparation method and Gram staining. Streaking methods were performed on both blood agar and glucose agar. The isolated pathogens were than tested regarding their sensitivity using Kirby Bauer disk diffusion test to the following antibiotics: Amoxicillin and clavulanic acid, Cefquinome, Enrofloxacin, Florfenicol, Gentamicin, Linco-spectin and Mastidiscs. The results demonstrated that single pathogens were involved in mastitis etiology in most of the cases, with rare associations. Staphylococci and streptococci strains were most frequently isolated, in 8 samples each, followed by E. coli with 4 strains and Klebsiella, Bacillus cereus and Corynebacterium in 1 sample. Regarding overall sensitivity, Amoxicillin and clavulanic acid was the most efficient antibiotic with an average of the inhibition area of 22.13 mm, followed by Mastidiscs (21.57 mm), Enrofloxacin (21.17 mm), Linco-spectin (18.71 mm), Cefquinome (18.33), Florfenicol (17.76 mm) and Gentamicin (16.57). Our result demonstrates a good overall sensitivity of the tested strains.


cow milk, mastitis, bacteria, antibiotic sensitivity

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