Risk factors for human Mycobacterium bovis infections in an urban area of Brazil

BACKGROUND The World Health Organization (WHO) has classified human zoonotic tuberculosis (TB) due to Mycobacterium bovis as a neglected issue in the developing world. In a recent cross-sectional study in Brazil, three of 189 TB patients presented with a coinfection of M. bovis and M. tuberculosis and were selected as cases for this study. OBJECTIVE The aim was to evaluate risk factors (RF) for zoonotic TB in an urban area of Brazil in order to guide preventive programmes. METHODS A matched case-control study was carried out nested within a cross-sectional study. For each of the three cases, 14 age- and sex-matched controls (TB due to M. tuberculosis) were selected. FINDINGS Zoonotic potential exposures (ZE) and extrapulmonary TB (EPTB) were independently associated with zoonotic TB in multivariate analyses. CONCLUSIONS ZE by occupation and consumption of raw milk and derivative products that place individuals in direct and indirect contact with animals and their excretions/secretions increase the risk for zoonotic TB in Brazil, especially among those with EPTB. Therefore, measures such as efficient control of bovine TB, distribution of pasteurised milk and its derivative products, and the diagnosis and monitoring of zoonotic TB in humans are essential steps, especially in developing countries where bovine TB is enzootic, and further studies are necessary.

Tuberculose: perfil epidemiológico em hospital referência no tratamento da doença / Tuberculosis: epidemiological profile in a reference hospital in the treatment of disease

OBJETIVO: Este estudo transversal objetivou determinar o perfil epidemiológico, clínico e diagnóstico de pacientes portadores de micobactérias entre março de 2008 e fevereiro de 2010. MÉTODO: A coleta de dados foi feita junto aos prontuários médicos e pacientes. RESULTADOS: De 175 casos, 170 com Mycobacterium tuberculosis, dois M. tuberculosis/complexo M. avium, dois complexo M. avium e um M. bovis/M. tuberculosis. 75,4% dos casos em pacientes do sexo masculino, com mediana etária de 40 anos, 14,3% em HIV positivos, 32% com renda familiar baixa e moradia precária. A doença pulmonar ocorreu em 94,9%. 45,1% se curaram, 24,0% abandonaram o tratamento e 9,7% vieram a óbito. A supervisão do tratamento ocorreu em 60% dos casos e em 56% com investigação para HIV. Das 9,6% amostras paucibacilares e 55,5% das extrapulmonares, o diagnóstico só foi possível pela cultura. CONCLUSÃO: Evidenciou-se predileção por indivíduos masculinos, com doença pulmonar, muitos sem positividade para HIV conhecida e com supervisão de tratamento parcial. A cultura foi uma importante ferramenta diagnóstica, complementar a baciloscopia.

This cross-sectional descriptive study aimed to determine the epidemiological, clinical and diagnosis of patients with mycobacteria between March 2008 and February 2010, in Juiz de Fora, Minas Gerais State. Methods: Data collection was performed at the medical records and patients. Results: In 175 cases, 170 with Mycobacterium tuberculosis, two M. tuberculosis/M. avium complex, two M. avium complex and oneM. bovis/M. tuberculosis. 75.4% of cases in male patients, meian age 40 years, 14.3% in HIV positive, 32% with low family income and poor housing. Pulmonary disease occurred in 94.9%. 45.1% were cured, 24.0% abandoned the treatment and 9.7% died. Supervision of treatment occurred in 60% of cases and 56% of cases was tested for HIV. 9.6% of paucibacillary specimens and 55.5% of extrapulmonary TB the diagnosis was possible only by culture. Conclusion: Was a clear predominance of the disease in male patients with pulmonary tuberculosis. The treatment was partially observed and several pacients with no known diagnosis of HIV. The use of mycobacterial culture was an important diagnostic tool, complementary to smear.

Tuberculosis patients co-infected with Mycobacterium bovis and Mycobacterium tuberculosis in an urban area of Brazil

In this cross-sectional study, mycobacteria specimens from 189 tuberculosis (TB) patients living in an urban area in Brazil were characterised from 2008-2010 using phenotypic and molecular speciation methods (pncA gene and oxyR pseudogene analysis). Of these samples, 174 isolates simultaneously grew on Löwenstein-Jensen (LJ) and Stonebrink (SB)-containing media and presented phenotypic and molecular profiles of Mycobacterium tuberculosis, whereas 12 had molecular profiles of M. tuberculosis based on the DNA analysis of formalin-fixed paraffin wax-embedded tissue samples (paraffin blocks). One patient produced two sputum isolates, the first of which simultaneously grew on LJ and SB media and presented phenotypic and molecular profiles of M. tuberculosis, and the second of which only grew on SB media and presented phenotypic profiles of Mycobacterium bovis. One patient provided a bronchial lavage isolate, which simultaneously grew on LJ and SB media and presented phenotypic and molecular profiles of M. tuberculosis, but had molecular profiles of M. bovis from paraffin block DNA analysis, and one sample had molecular profiles of M. tuberculosis and M. bovis identified from two distinct paraffin blocks. Moreover, we found a low prevalence (1.6%) of M. bovis among these isolates, which suggests that local health service procedures likely underestimate its real frequency and that it deserves more attention from public health officials.

Mycobacterium leprae in six-banded (Euphractus sexcinctus) and nine-banded armadillos (Dasypus novemcinctus) in Northeast Brazil

Human beings are the main reservoir of the causative agent of leprosy, Mycobacterium leprae. In the Americas, nine-banded armadillos (Dasypus novemcinctus) also act as a reservoir for the bacillus. In the state of Ceará (CE), which is located in Northeast Brazil and is an endemic area of leprosy, there are several species of armadillos, including D. novemcinctus and Euphractus sexcinctus (six-banded armadillo). Contact between humans and armadillos occur mainly through hunting, cleaning, preparing, cooking and eating. This study identified M. leprae DNA in the two main species of armadillos found in Northeast Brazil. A total of 29 wild armadillos (27 D. novemcinctus and 2 E. sexcinctus) were captured in different environments of CE countryside. Samples from the ear, nose, liver and spleen from each of these animals were tested by a nested M. leprae-specific repetitive element polymerase chain reaction assay. The samples that tested positive were confirmed by DNA sequencing. M. leprae was detected in 21% (6/29) of the animals, including five D. novemcinctus and one E. sexcinctus. This is the first Brazilian study to identify the presence of a biomarker of M. leprae in wild armadillos (D. novemcinctus and E. sexcinctus) in a leprosy hyperendemic area where there is continuous contact between humans and armadillos.

Identification of Mycobacterium tuberculosis complex based on amplification and sequencing of the oxyR pseudogene from stored Ziehl-Neelsen-stained sputum smears in Brazil

A cross-sectional analysis of stored Ziehl-Neelsen (ZN)-stained sputum smear slides (SSS) obtained from two public tuberculosis referral laboratories located in Juiz de Fora, Minas Gerais, was carried out to distinguish Mycobacterium bovis from other members of the Mycobacterium tuberculosis complex (MTC). A two-step approach was used to distinguish M. bovis from other members of MTC: (i) oxyR pseudogene amplification to detect MTC and, subsequently, (ii) allele-specific sequencing based on the polymorphism at position 285 of this gene. The oxyR pseudogene was successfully amplified in 100 of 177 (56.5 percent) SSS available from 99 individuals. No molecular profile of M. bovis was found. Multivariate analysis indicated that acid-fast bacilli (AFB) results and the source laboratory were associated (p < 0.05) with oxyR pseudogene amplification. SSS that were AFB++ SSS showed more oxyR pseudogene amplification than those with AFB0, possibly due to the amount of DNA. One of the two source laboratories presented a greater chance of oxyR pseudogene amplification, suggesting that differences in sputum conservation between laboratories could have influenced the preservation of DNA. This study provides evidence that stored ZN-SSS can be used for the molecular detection of MTC.