ABSTRACT
ABSTRACT The modified Middlebrook 7H11 cultivation technique was comparedwith the tradicional culture techniqueby using the Stonebrink medium. The purpose of this comparison was to to evaluate the sensitivity and the time for the detection of positive cultures of mycobacteria in milk samples experimentally inoculated with Mycobacterium bovis (strain AN5), at a dilution of 10-2 , and submitted to two types of procedures: technique 1 (skin milk) and technique 2 (pellet), decontamined by modified the Petroff´s method, added with Tween 80, and compared with total milk samples submitted to tradicional Petroff method in the same media types. The results of the two tecniques were compared with each other by the non-parametric Wilcoxon test and Mann-Whitney. The results obtained from this experiment showed that: techniques 1 and 2 produced great number of colonies and higher proportion of positive culture than the tradicional one by using total milk; the time needed for the detection of mycobacteria colonies was slightly shorter by the thin layer technique than by the tradicional culture method; in order to improve the epidemiological surveillance, this technique should be used as a complementary method to the tradicional one in the diagnosis of bovine tuberculosis.
RESUMO O meio de Middlebrook 7H11 modificado foi comparado ao meio de Stonebrink, a fim de se avaliar a sensibilidade e o tempo de detecção de micobactérias em amostras de leite, experimentalmente inoculadas com Mycobacterium bovis (estirpe AN5), em uma diluição 10-2, e submetidas a duas diferentes técnicas de processamento: gordura (técnica 1) e sedimento (técnica 2), descontaminadas pelo método de Petroff modificado (adicionado de Tween 80), confrontadas com a técnica do leite total submetida ao método de Petroff tradicional. Os resultados destas técnicas (1 e 2) foram comparados entre si pelos testes não paramétricos de Wilcoxon e de MannWhitney e demonstraram que as técnicas 1 e 2 forneceram maior recuperação de micobactérias e proporção de cultivos positivos nos meios de Stonebrink e Middlebrook 7H11; o meio de Middlebrook 7H11 permitiu a visualização precoce das micobactérias, podendo ser utilizado como uma técnica de diagnóstico rápida da tuberculose bovina, em amostras de leite, para fins de vigilância epidemiológica.