Isolation of brucella spp from milk of brucellosis positive cows in São Paulo and Minas Gerais states

Abstract

Brucellosis is a chronic zoonosis that plays an important role in Public Health. Considering the lack of data in Brazil regarding its presence in raw milk and non-pasteurized dairy products, we determined the presence of brucellae in milk from brucellosis positive animals. The slide agglutination test (SAT), tube agglutination test (TAT) and TAT treated with 2-mercaptoethanol were used to identify positive animals in studied herds. For 3 days, 300 ml milk samples/cow (75 ml/teat) were collected from all productive quarters of the positive animals. These were mixed and centrifuged. Part of the pellet and of the supernatant were inoculated in Farrel and Brodie-Sinton (BS) media supplemented with antimicrobial agents. The inoculated plates and tubes were incubated at 37ºC for 7 days, with 10 per cent CO2 atmosphere. The suspected bacterial growth in BS media was immediately cultivated in agar Brucella media, under the same conditions. Colonies were submitted to identification procedures including Gram stain, CO2 requirement, H2S production, urease activity and growth in the presence of thionin and fuchsin. Of the 49 analysed samples, 15 (30.61%) contained Brucella abortus. The distribution was as follows: biotype 1 in one sample (2.04%), biotype 2 in eight (16.32%) and biotype 3 in six samples (12.25%).