IS6110 restriction fragment length polymorphism of Mycobacterium tuberculosis isolated from patients with pulmonary tuberculosis in Campinas, Brazil: evidence of intercontinental distribution of strains

Tuberculosis (TB) is a major concern in developing countries. In Brazil, few genotyping studies have been conducted to verify the number of IS6110 copies present in local prevalent strains of Mycobacterium tuberculosis, the distribution and clustering of strains. IS6110 DNA fingerprinting was performed on a sample of M. tuberculosis isolates from patients with AFB smear-positive pulmonary TB, at a hospital in Brazil. The IS6110 profiles were analyzed and compared to a M. tuberculosis database of the Houston Tuberculosis Initiative, Houston, US. Seventy-six fingerprints were obtained from 98 patients. All M. tuberculosis strains had an IS6110 copy number between 5-21 allowing for differentiation of the isolates. Human immunodeficiency virus infection was confirmed in nearly half the patients of whom data was available. Fifty-eight strains had unique patterns, while 17 strains were grouped in 7 clusters (2 to 6 strains). When compared to the HTI database, 6 strains matched isolates from El Paso, Ciudad de Juarez, Houston, and New York. Recently acquired infections were documented in 19% of cases. The community transmission of infection is intense, since some clustered strains were recovered during the four-year study period. The intercontinental dissemination of M. tuberculosis strains is suspected by demonstration of identical fingerprints in a distant country

Susceptibility of Mycobacterium tuberculosis to first-line antimycobacterial agents in a Brazilian hospital: assessing the utility of the tetrazolium (MTT) microplate assay

We conducted a cross-sectional, hospital-based study between January 2006-March 2008 to estimate the resistance of Mycobacterium tuberculosis to first-line drugs in patients with tuberculosis at a Brazilian hospital. We evaluated the performance of the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide] (MTT) microplate assay compared with the Bactec-MGIT 960™ system for mycobacteria testing. The prevalence of resistance in M. tuberculosis was 6.7%. Multidrug-resistance [resistance to rifampicin (RMP) and isoniazid (INH)], INH-resistance and streptomycin (SM)-resistance accounted for 1%, 3.8% and 3.8% of all resistance, respectively, and all isolates were susceptible to ethambutol (EM). The resistance was primary in four cases and acquired in three cases and previous treatment was associated with resistance (p = 0.0129). Among the 119 M. tuberculosis isolates, complete concordance of the results for INH and EM was observed between the MTT microplate and Bactec-MGIT 960TM methods. The observed agreement for RMP was 99% (sensitivity: 90%) and 95.8% for SM (sensitivity 90.9%), lower than those for other drugs. The MTT colourimetric method is an accurate, simple and low-cost alternative in settings with limited resources

Análise molecular de cepas de Mycobacterium tuberculosis provenientes de um centro de saúde ambulatorial em Porto Alegre, (RS) Molecular analysis of Mycobacterium tuberculosis strains from an outpatient clinic in Porto Alegre, (RS)

INTRODUÇÃO: A tuberculose é uma doença antiga que ainda se mantém como um dos maiores males da humanidade no século XXI. Nas últimas décadas, o advento de novas tecnologias utilizando os conhecimentos de biologia molecular tem levado a um aumento na investigação da etiologia, detecção e epidemiologia da tuberculose. OBJETIVO: Avaliar o grau de similaridade entre as cepas de Mycobacterium tuberculosis provenientes do setor de tisiologia do Centro de Saúde Navegantes, de Porto Alegre (RS). MÉTODO: Foi realizado um estudo retrospectivo utilizando 55 amostras de escarro de pacientes atendidos ambulatorialmente no Centro de Saúde Navegantes para realização da técnica de RFLP. Os resultados obtidos pela genotipagem foram correlacionados com os dados gerados a partir da epidemiologia convencional. RESULTADOS: Trinta e nove isolados (70,9%) apresentaram padrão único, enquanto dezesseis isolados (29,1%) apresentaram padrões agrupáveis e formaram 8 clusters, com 2 pacientes em cada. Foi encontrada relação epidemiológica em 6 (37,5%) dos 16 pacientes em cluster. CONCLUSÃO: A associação adequada entre epidemiologia convencional e genotipagem de M. tuberculosis contribui para um melhor entendimento da dinâmica de transmissão da tuberculose mesmo quando o estudo é realizado em um único local.<br>BACKGROUND: Tuberculosis is an ancient disease, which still remains one of the major ills faced by mankind in the 21st century. In recent decades, new technologies employing the knowledge gained from molecular biology studies have allowed for more accurate detection of tuberculosis and increased investigation of the etiology and epidemiology of the disease. AIM: Evaluating the degree of similarity among strains of Mycobacterium tuberculosis provided by the Phthisiology Sector of Centro de Saúde Navegantes (Navegantes Health Clinic) in Porto Alegre, RS, Brazil. METHOD: A retrospective study was performed involving RFLP typing of 55 sputum samples from outpatients examined at the Centro de Saúde Navegantes. The results of the genotyping were correlated to the conventional epidemiology data. RESULTS: A single pattern was seen in 39 (70.9%) of the isolates, whereas 16 isolates (29.1%) showed clustering patterns and were grouped into 8 clusters of 2 patients each. An epidemiological link was found for 6 (37.5%) of the 16 patients in the clusters. CONCLUSION: The appropriate combination of conventional epidemiology and genotyping of M. tuberculosis contributes to a better understanding of the dynamics of tuberculosis transmission even when such a study is performed in a single, isolated health clinic

Resistência do Mycobacterium tuberculosis às drogas em pacientes HIV+ em cinco municípios da Baixada Santista, São Paulo, Brasil Mycobacterium tuberculosis drug resistance in HIV patients in Baixada Santista, São Paulo, Brazil

No início dos anos 90, observou-se aumento da resistência do Mycobacterium tuberculosis às drogas antituberculose, com alta prevalência entre pacientes HIV+. Neste estudo, foram avaliados a freqüência de resistência, o perfil de sensibilidade do M. tuberculosis às drogas e os fatores predisponentes à resistência entre indivíduos HIV+ nos municípios de Santos, São Vicente, Cubatão, Praia Grande e Guarujá, Estado de São Paulo, Brasil. Foram pesquisados os prontuários de 301 pacientes com resultado de cultura positivo entre 1993 e 2003. A resistência ocorreu em 57 (18,9%) pacientes com a seguinte distribuição: 32 (10,6%) apresentaram tuberculose multirresistente (resistência ao menos à Rifampicina e Isoniazida); 4 (1,3%) casos apresentaram resistência a duas ou mais drogas e 21 (7%) à monorresistência. Observou-se resistência secundária em 70,2% dos casos. Estatisticamente associadas à tuberculose resistente foram: tratamento anterior com drogas antituberculose, tempo de diagnóstico de HIV e hospitalização prévia. Em análise multivariada, apenas tratamento anterior, ajustado por faixa etária, mostrou-se associado (OR = 5,49; IC95%: 2,60-11,60). A ocorrência de resistência em 18,9% dos casos e multirresistência em aproximadamente 10% confirmam a relevância deste problema entre pacientes HIV+ na Baixada Santista.<br>Since the early 1990s, an increase in Mycobacterium tuberculosis drug resistance has been reported, with high prevalence among HIV+ patients. We evaluated the sensitivity patterns of M. tuberculosis, resistance rate, and predisposing factors among HIV+ patients in Santos, São Vicente, Cubatão, Praia Grande, and Guarujá, São Paulo State, Brazil. The medical charts of 301 patients with positive cultures for M. tuberculosis from 1993 to 2003 were reviewed. Resistance occurred in 57 patients (18.9%), as follows: 32 (10.6%) displayed multidrug-resistant tuberculosis (resistant to at least Rifampicin and Isoniazid); 4 (1.3%) were resistant to two or more drugs; and 21 (7%) were resistant to a single drug. Acquired resistance was observed in 70.1% of cases. Drug resistance was significantly associated with previous tuberculosis treatment, duration of HIV diagnosis, and previous hospitalization. In logistic regression analysis, only previous tuberculosis treatment adjusted by age remained as an independent risk factor (OR = 5.49; 95%CI: 2.60-11.60). Drug resistance to at least one drug in 18.9% and multidrug resistance in 10.6% of cases highlight the relevance of this problem in HIV patients in the Baixada Santista