Polymerase chain reaction for the direct detection of Brucella spp. in milk and cheese.

A polymerase chain reaction test was developed to detect Brucella spp. directly in milk and cheese and optimized using primers for the BSCP-31 gene. A total of 46 cheese samples produced with sheep and goats milk were assayed, and Brucella spp. was detected in 46% of them, especially in cheese made from sheep milk. This method is of remarkable epidemiologic interest because it is an indirect test indicating the sanitary quality of milk used in dairy industries. The method showed good sensitivity and specificity. It is faster and less expensive than the conventional bacteriological assays.