Survival of Brucella Melitensis Rev - 1 in Experimentally Contaminated and Refrigerated Camel and Goat Milk

Abstract

This research work aimed to examine the survival of Brucella melitensis Rev-1 in refrigerated camel and goat milk. Fresh camel and goat milk was experimentally contaminated with different concentrations of colony forming units per ml (CFU/ml) of Brucella melitensis Rev-1 and refrigerated for different periods of time. Brucella melitensis Rev-1 was detected in the refrigerated contaminated milk by isolation in culture medium and by PCR. Brucella melitensis Rev-1 was isolated from camel milk samples refrigerated for up to 8 hours. Camel milk samples refrigerated for 24 hours were negative for bacterial isolation. Brucella melitensis Rev-1 was isolated from camel milk samples containing 65 (CFU/ml) while samples containing less than that were negative for culture. The minimum content of the bacterium to be detected by PCR in contaminated camel milk was 65 CFU/ml. The higher the bacterial content of milk the better is the isolation results and whole milk was superior to cream for isolation. Brucella melitensis Rev-1 was isolated from goat milk refrigerated for up to 72 hrs. Isolation was positive for samples containing as low as 3 CFU/ml refrigerated for 4 hrs. Brucella melitensis Rev-1 was isolated from contaminated goat milk samples containing 30 to 300 CFU/ml refrigerated for 24 and 48 hrs, respectively. Samples containing higher bacterial concentrations were positive for isolation after 72 hrs of refrigeration. PCR was positive for Brucella melitensis Rev-1-contaminated goat milk containing as low as 3 CFU/ml. These results show that both isolation and PCR are sensitive for the detection of milk contamination with Brucella melitensis Rev-1, and that Brucella melitensis Rev-1 will not survive in camel milk for more than 8 hrs. the difference found here may be attributed to the nature of milk itself.