Thesis (M.Sc.) - Cairo University - Faculty of Veterinary Medicine - Department of Microbiology

For conducting this work 104 quarters milk samples (QMS) were collected from apparently healthy animals. The severity of subclinical mastitis in 104 quarter milk samples was illustrated. , 84 examined isolates of positive CMT bovine quarter milk samples were inoculated in the B. cereus selective medium (DifcoTM MYP), B. cereus suspected isolates were detected in only 22 of cultivated plates in a percentage of 26.19% of examined samples. BCET-RPLA technique was carried out on a total number of (20) isolates out of 22 isolates already identified biochemically. The test revealed that out of (20) examined isolates, only 4(20%) isolates were positive (produced diarrheal toxins); while the remaining isolates 16(80%) were negative for toxins production. Among the 20 tested strains PCR technique was carried out for (4) isolates) identified as positive for toxin production by BCET-RPLA technique. The PCR test confirmed that out of (20) examined isolates, only (4) isolates were positive (produced toxins), while the remaining isolates (16) were negative for toxins production. So in this concern and as a result obtained here in this work, the problem with B. cereus is the association of this organism with subclinical mastitis, so the problem with B. cereus extends beyond the soiling of the udders of cows to the association of this organism with subclinical mastitis it is very important

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