P-062. Isolation and Characterization of Brucella Strains Isolated from Chihuahua Cheese Elaborated with Unpasteurized Milk

G. L. Viezcas-Valenzuela1, L. E. Escobedo-Morales1, M. L. Aceves-Bassanetti1, M. G. Gastélum-Franco1, N. Herrera-Díaz1, M. Contreras2, G. V. Nevárez-Moorillón1, B. E. Rivera-Chavira1;
1Univ. Autonoma de Chihuahua, Chihuahua, MEXICO, 2Programa COESPRIS. Edo. Chihuahua, Chihuahua, MEXICO.

Brucellosis is a zoonotic disease that causes economical problems in the meat and dairy industry, because infected cattle need to be sacrificed. In humans, the infection is usually chronic, and is considered as a severe public health problem. Dairy products are often related to food outbreaks, and methods used for isolation of Brucella do not have a good recovery percentage, due to the complex matrix of foods. The state of Chihuahua is one of the main milk producers in Mexico, and a large proportion of this product is used in the elaboration of Chihuahua cheese, that is a cheddar cheese with a distinctive flavor. Many cheese factories are family business or small factories that produce Chihuahua cheese using unpasteurized milk, with a deleterious effect on the sanitary quality of the product. The aim of this work was to standardize microbiological and molecular methods for isolation and characterization of Brucella from Chihuahua cheese elaborated with unpasteurized milk, as well as to screen cheese elaborated in the central part of Chihuahua for this pathogen. Cheese samples (25g) were homogenized in a Tween 80 solution (2%) and 10 ml of the suspension were inoculated in 90 ml of enrichment culture (Brucella broth added with antibiotics) and were incubated at 37°C for 48 h. Culture was inoculated later into modified Farrell Agar and colonies were identified by morphological and biochemical tests. Strain identification was also performed by PCR with specific primers for the genus Brucella. In order to standardize the method, cheese elaborated with pasteurized milk was intentionally inoculated with Brucella melitensis, and a large number of cells were necessary to detect the pathogen (1.5X105 cfu/ml). A total of 90 cheese samples elaborated with unpasteurized milk, obtained from the central part of the state of Chihuahua were processed, and in 46 samples suspected colonies were identified. Nine strains were positive according to biochemical tests results, and six were confirmed by PCR. Presence of Brucella in Chihuahua cheese represents a public health risk, and even though the method does not have a good recovery, a small number of cells can cause the disease, and further optimization of the method is required.