Thesis (Ph.D.) - Cairo University - Faculty of Veterinary Medicine - Department of Microbiology

In this study, 338milk samples collected from buffaloes were identified as 104 normal milk samples,148 subclinical mastitic milk samples and 86 clinical mastitic milk samples .While the total 48 cow's milk samples were differentiated as 20 normal milk samples,18 subclinical mastitic milk samples and 10 clinical mastitic milk samples. Bacterial isolation and identification indicated that 88 and 6 coagulase negative staphylococci (CNS) isolates recovered from buffalo's and cow's milk samples respectively. We differentiate 94 isolates of CNS by API .Using the disc diffusion test for investigating the in vitro sensitivity of 94 CNS against 10 antimicrobial drugs revealed a resistance to Oxacillin, Ampicillin, Penicillin, Tetracycline, Vancomycin and Rifamin in an incidence of 46 (48.9%), 40 (42.6%), 30 (32%), 24 (25.5%), 8 (8.5%) and 4 (4.3%) respectively. Most of the CNS species were Congo red positive and constituted 66 isolates in a percentage 70.2%. Also testing the ability of CNS isolates to produce slime by Christensen's tube (CT) method was done. Most of isolates showed absent and week degree constituted 42(44.7%) and 28 (29.8%) respectively, while both moderate and strong degrees constituted 12(12.8 %) of the isolates

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