RESUMO
Multilocus enzyme electrophoresis (MLEE) of 99 Brucella isolates, including the type strains from all recognized species, revealed a very limited genetic diversity and supports the proposal of a monospecific genus. In MLEE-derived dendrograms, Brucella abortus and a marine Brucella sp. grouped into a single electrophoretic type related to Brucella neotomae and Brucella ovis. Brucella suis and Brucella canis formed another cluster linked to Brucella melitensis and related to Rhizobium tropici. The Brucella strains tested that were representatives of the six electrophoretic types had the same rRNA gene restriction fragment length polymorphism patterns and identical ribotypes. All 99 isolates had similar chromosome profiles as revealed by the Eckhardt procedure.
Assuntos
Brucella/classificação , Brucelose/microbiologia , Laticínios/microbiologia , Variação Genética , Animais , Brucella/enzimologia , Brucella/genética , Brucella/isolamento & purificação , Bovinos , DNA Bacteriano/análise , DNA Bacteriano/genética , DNA Ribossômico/análise , DNA Ribossômico/genética , Cães , Eletroforese em Gel de Amido/métodos , Enzimas/análise , Humanos , Hibridização de Ácido Nucleico , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/genética , RibotipagemRESUMO
The diagnostic value of bacteriological and serological methods for the laboratory diagnosis of brucellosis was studied. In the analysis of milk and cheese specimens Brucella cultures were isolated and differentiated as B.melitensis, biovar I, and B.abortus, biovar 4. In 25.6% of cases B.melitensis culture, biovar 1, was isolated from the blood of persons suspected for brucellosis. The isolation of B.melitensis culture from milk showed that this infective agent migrated from small animals to cattle, which was indicative of a high risk of human infection in the state of Zacatecas, Mexico. The comparative evaluation of serological diagnostic methods (the agglutination test in test tubes, Huddleson's slide test, the acidic rose bengal test and the 2-mercaptoethanol test) showed high sensitivity of rapid tests (Huddleson's test and the rose bengal test in 93.7% and 87.9% of cases respectively). The 2-mercaptoethanol test which gave positive results in 63.8% of cases provided additional information characterizing the course of infections process.