Brucella spp. isolation from dogs from commercial breeding kennels in S?o Paulo state, Brazil

摘要

Dogs from 12 commercial breeding kennels were submitted to clinical investigation and laboratorial tests for diagnosis of Brucella spp. infection. The sampling was carried out between April 2000 and February 2002 and the laboratorial tests employed were agar gel immunediffusion test (AGID) and blood culture. From 171 dogs examinated, 39 (22.8%) showed at least one clinical sign compatible with brucellosis, 58 (33.91%) were AGID positive and 24 (14.03%) were positive by blood culture. Gram negative bacterial cells with a biochemical pattern compatible with that of bacteria belonging to genus Brucella were isolated from blood specimens of 24 animals. According to Kappa index and McNemar test, the association between AGID and blood culture (k=0.360 with 95% of confidence interval; X2=25.93, p=0.000), between AGID and clinical test (k=0.248 with 95% of confidence interval; X2=6.11, p=0.013), and between blood culture and clinical examination (k=0.442 with 95% of confidence interval; X2=6.76, p=0.009) were not statistically significant. Qui-Square test indicated no association of sex and the results of clinical examination (X2=1.35 and p=0.2447), AGID (X2=1.58 and p=0.2086) or bacterial isolation (X2=1.48 and p=0.2230). Within 12 kennels, seven had at least one dog positive by blood culture and nine had at least one animal positive by AGID. The association of epidemiological data with direct and indirect methods of diagnosis is necessary to perform a definitive diagnosis of Brucella infection in dogs, as positive results by AGID can be consequence of non-specific reactions and must be confirmed by blood culture. Negative results by AGID must also be confirmed using direct methods of diagnosis or repeating the serologic test after 30 days, because of the low sensitivity of this test.