Infection by Mycobacterium bovis in a dog from Brazil

Tuberculosis (TB) is a chronic disease caused by bacteria belonging to the Mycobacterium tuberculosis complex (MtbC). This disease rarely affects dogs. Canine infections are usually caused by M. tuberculosis. Mycobacterium bovis infections are rare in dogs and associated with consumption of raw milk or contaminated products. Here, we report a Boxer dog who had a M. bovis infection and was admitted to a Brazilian veterinary hospital with a presumptive diagnosis of chronic ehrlichiosis. Despite receiving treatment for chronic ehrlichiosis, it progressed to death. TB was diagnosed during post-mortem examinations using histopathological analysis. Ziehl-Neelsen staining revealed acid-fast bacilli in the kidneys, liver, mesentery, and a mass adhered to the liver. Further, PCR-restriction analysis was performed to identify mycobacteria in the samples. A restriction profile compatible with MtbC was found in the lungs. In addition, PCR-based MtbC typing deletions at different loci of chromosome 9 enabled the identification of M. bovis in the lungs. Therefore, it is very essential to perform differential diagnosis of TB in dogs with non-specific clinical signs and who do not respond to treatment, particularly those who had been in contact with TB-infected cattle or owners. Further, we highlight the use of molecular methods for the identification of bacilli, improving the diagnosis and aiding epidemiological studies.(AU)

Desenvolvimento de Reações em Cadeia pela Polimerase (PCRs) para o diagnóstico diferencial das principais espécies de Brucella / Development of Polymerase Chain Reactions (PCRs) for differential diagnosis of the main species of the genus Brucella

A brucelose é uma doença altamente contagiosa, responsável por grandes prejuízos econômicos e de saúde pública. É causada por bactérias do gênero Brucella, cujas espécies e seus biovares costumam ser caracterizados pelo isolamento e identificação de características fenotípicas da colônia. Dificuldades como, o perigo na manipulação dos microrganismos, processos laboriosos de tipificação, demora na obtenção de resultados e a instabilidade de características fenotípicas ou isolamento de linhagens atípicas dificultam a tipificação e encorajaram a busca de técnicas mais sensíveis e específicas, como a PCR, que resolveria as dificuldades e facilitaria a investigação epidemiológica dos casos humanos e animais. Diversas análises e o sequenciamento de determinados genes e do genoma completo de algumas espécies, demonstraram a existência de polimorfismos únicos no DNA das brucelas, que podem ser utilizados na sua identificação. Baseado nas dificuldades de identificação e na descoberta de polimorfismos únicos no DNA bacteriano das espécies, nosso objetivo foi desenvolver primers específicos para identificação de seis espécies do gênero B. abortus, B. melitensis, B. suis, B. canis, B. ovis e B. neotomae, e padronizar PCRs que permitissem identificá-las com maior sensibilidade e rapidez. Tentamos caracterizar marcadores moleculares para o desenho de primers espécie-específicos, através da amplificação randômica e clonagem dos fragmentos específicos, sem resultados satisfatórios. Apenas um primer para B. abortus foi conseguido quando foram analisados os polimorfismos já descritos na literatura. Assim, realizou-se o alinhamento múltiplo das sequências dos cromossomos I e II das espécies de Brucella, que permitiu a identificação de vários eventos polimórficos específicos para cada espécie, dos quais foram escolhidas regiões potenciais para o desenho de sete primers (dois para B. canis, B. melitensis e B. ovis, e outro para B. canis/B. suis) que tiveram sua especificidade analítica verificada com o programa Primer BLAST e testada nas 18 cepas de referência de Brucella, compreendendo a B. abortus, B. melitensis, B. suis e seus biovares, além da

Brucellosis is responsible for great economic losses and serious impact on public health. This infectious disease is caused by bacteria of the genus Brucella, whose species and their respective biovars are often characterized by isolation and identification of differences in phenotypic tests. The complex and laborious process of Brucella typing, comprising the danger in handling of microorganisms, delay in obtaining results and instability of phenotypic characteristics or isolation of atypical strains, stimulated the search for more sensitive and specific techniques such as PCR. This technique would facilitate the epidemiological investigation of human and animal cases. Several analyses even as sequencing of certain genes and the complete genome of some species, demonstrated the existence of polymorphisms in the DNA of Brucella, which can be used to identify them. Due to typing difficulties and discovery of single polymorphisms in DNA bacterial species, our goals were to develop specific primers for identification of six species of the genus B. abortus, B. melitensis, B. suis, B. canis, B. ovis and B. neotomae and standardize PCRs to identify them with greater sensitivity and speed. We tried to characterize species-specific molecular markers using random amplification and cloning of specific fragments to design primers, without satisfactory results. Only one primer based on polymorphisms already described in the literature was successful for B. abortus specie differentiation. Thus, we performed the multiple alignment of the complete sequences of chromosomes I and II of Brucella species. This approach allowed the identification of several specie-specific polymorphic events, from which potential regions were chosen for the design of seven primers (two for B. canis, B. melitensis and B. ovis, and one for B. canis / B. suis). The analytical specificity of all primers was verified with the Primer BLAST software. Tests with specific primers were performed on 18 reference strains of Brucella, including all the six species of the genus Brucella and 231 field strains of B. abortus, B. canis and B. suis. The PCRs showed the expected fragment amplification in almost all reference and field strains, except for the B. canis and the B. canis / B. suis primers. Ours results suggest that these PCRs are able for Brucella species differentiation

Avaliacão das técnicas de cultivo microbiológico e soroaglutinação rápida em cartão com e se 2-Mercaptoetanol da Brucelose canina

A brucelose canina causada pela Brucella canis (B. canis) é uma das principais causas infecciosas de desordens reprodutivas em cães. O presente trabalho teve como objetivo comparar as técnicas de Cultivo Microbiológico e Soroaglutinação Rápida em Cartão (SAR) com e sem o emprego de 2-Mercaptoetanol (2-ME) no diagnóstico da brucelose canina. Adicionalmente foram avaliados sangue, urina, swab vaginal, prepucial e sêmen como materiais a serem processados no diagnóstico microbiológico. Foram avaliados 236 cães quanto à infecção por B. canis, muitos com histórico de problemas reprodutivos, dos quais 24,2% resultaram positivos na SAR, 10,2% na SAR-2ME, 28% na hemocultura, 9,2% na urocultura, 2,1% na cultura de swab vaginal, 13,6% na cultura dos swabs prepuciais e 28,6% no cultivo de sêmen. Dos 71 animais positivos no cultivo microbiológico, 92,9% apresentaram-se positivos na hemocultura. Nos demais materiais foram obtidos percentuais menores. A sensibilidade relativa da SAR resultou em 66,2% e a especificidade relativa 93,9%. A SAR-2ME apresentou sensibilidade relativa de 29,5% com ligeiro aumento na especificidade relativa 98,2%. Quando associados SAR e hemocultura foram observados 97,6% e 93,9% de sensibilidade e especificidade, respectivamente. Os resultados sugerem a utilização associada da SAR à hemocultura sem realização em paralelo com 2-ME

Canine brucellosis caused by Brucella canis (B. canis) is one of the major infectious causes of reproductive disorders in dogs. The present study aimed to compare the performance of bacteriological methods and Rapid Slide Agglutination Test (RSAT) with or without 2-Mercaptoethanol (2-ME) in canine brucellosis diagnosis. Additionally, blood, urine, vaginal and prepucial swabs and semen were evaluated regarding their use in bacteriological diagnostic. Two hundred thirty six dogs, many of them showing reproductive problems, were submitted to investigation for diagnosis of B. canis infection. Among them, 24.2% were positive in RSAT, 10.2% 2ME-RSAT, 28% blood culture, 9.2% urine culture, 2.1% vaginal swab culture, 13.6% prepucial swab culture and 28.6% semen culture. Among the 71 positive dogs in bacteriological culture, 92.9% were positive in blood culture. The percentage of positivity was variable in others samples. The relative sensitivity of RSAT was 66.2% and the relative specificity was 93.9%. The 2ME-RSAT presented lower sensitivity 29.5% and greater specificity 98.2%. The use of blood culture and RSAT associated presented 97.6% e 93.9% of sensibility and specificity, respectively. These results suggest that RSAT should be used with blood cultures independently of the use of 2ME-RSAT