Document Type : Research article
Author
Dept. of Food Control, Fac. of Vet. Med., Zagazig University.
Abstract
Quarter milk samples (n=200) from 50 dairy cows (Holstein breed) in Hohenheim region, Stuttgart, Germany, were examined to study the occurrence and causes of mastitis, distribution of mastitis pathogens and in vitro antimicrobial susceptibility of different mastitis pathogens. The study revealed that 75 (37.5 %) quarters had positive California mastitis test (CMT). 45 (60.0%) of them had CMT score 3, while 25 (33.3%) showed CMT score 2 and 5 (6.7 %) gave score 1. All positive quarters 75 (37.5 %) had significantly a higher mean value of somatic cell counts (437.3 x10 cells/mL). So, all these quarters were considered positive for mastitis 200.000 cells/mL). Bacteriological examination of these positive quarters (75) revealed that 63 (84.0 %) quarters yielded bacteria. Staphylococcus aureus, Stap < /em>h. epidermidis, Streptococcus uberis, Strept. agalactiae, Corynebacterium bovis and E. coli were the main organisms. These strains were isolated at varying percentages 14.2, 19.2, 26.6, 10.0, 17.5 and 12.5%, respectively. The average somatic cell counts calculated from quarter milk samples in relation to isolated bacterial strains were, 391.4,416.9, 476.4, 740, 357.3 and 542x10 cells/mL, respectively. According to in vitro antimicrobial susceptibility testing, the Staphylococcus aureus demonstrated the highest level of resistance (100.0 %) to Penicillin, lincomycin, Colistin, Triple sulfa, Bacitracin,
Chioramphenicol and Clindomycin. While, Staph. epidermidis (coagulase negative Staphylococci) gave the same resistance level against Triple sulfa, Bacitracin and Clindomycin. However, in case of Colistin and Polymyxin B it was decreased to 95.7%. All isolated strains of Streptococcus uberis (32) gave resistance to Triple sulfa, Bacitracin, Chloramphenicol and Clindomycin by a percentage of 100.0%. This percent was varying with other antibiotics where it became 96.9% with Colistin and Sulfamethoxazol and 87.5% against Neomycin and Trimethoprim. Streptococcus agalactiae isolated strains (12) were very susceptible to Erythromycin, Penicillin, Lincomycin, Amoxicillin, Ampicillin, Tetracycline, Oxacillin, Cefoperazon, Sulfamethoxazol and Cefalexin treatment. Corynebacterium bovis showed complete resistance (100.0%) with antibiotic discs of Trimethoprim, Triple sulfa, Bacitracin, Sulfamethoxazol, Chloramphenicol and Clindomycin. E. coli revealed 100.0 % resistance to Gentamycin and Triple sulfa and 80.0% to Amoxicillin, Polymyxin B, Colistin, Neomycin, Trimethoprim, Sulfamethoxazol and Cefalexin. The economic importance and public health significance of existing microorganisms as well as the suggested measures for improving the keeping quality as well as the sanitary condition of raw milk and its products were discussed.
Keywords
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