Abstract INTRODUCTION: We aimed to estimate the prevalence and transmission of drug-resistant tuberculosis in a high-burden Brazilian setting under directly observed therapy short-course strategy. METHODS: Isolates of culture-confirmed pulmonary tuberculosis patients from Guarulhos, Brazil, diagnosed in October 2007-2011 were subjected to drug susceptibility and IS6110-restriction fragment length polymorphism testing. RESULTS: The overall resistance prevalence was 11.5% and the multi-drug resistance rate was 4.2%. Twenty-six (43.3%) of 60 drug-resistant isolates were clustered. Epidemiological relationships were identified in 11 (42.3%) patients; 30.8% of the cases were transmitted in households. CONCLUSIONS: Drug-resistant tuberculosis was relatively low and transmitted in households and the community.

OBJETIVO: A diferenciação rápida entre Mycobacterium tuberculosis e micobactérias não-tuberculosas é fundamental para os pacientes coinfectados com tuberculose e HIV. Para tanto, utilizamos duas metodologias em nosso laboratório: detecção do fator corda e PCR-restriction enzyme analysis (PRA). O objetivo do estudo foi avaliar a acurácia desse teste de triagem em meio sólido como um método rápido para a identificação presuntiva do complexo M. tuberculosis, considerando custos e tempo de resultado. MÉTODOS: Foram processadas 152 cepas pelo teste de triagem combinado, que consistiu da detecção do fator corda por microscopia (esfregaço corado por Ziehl-Neelsen) e avaliação do aspecto macroscópico das colônias, e PRA (padrão ouro). Os custos foram estimados através da obtenção dos preços dos insumos necessários para a realização de cada teste. RESULTADOS: A acurácia da detecção do fator corda foi de 95,4% (IC95%: 90,7-98,1%) e a do teste de triagem combinado foi de 99,3% (IC95%: 96,4-100%). O custo da detecção do fator corda foi de R$ 0,60 e do PRA de R$ 16,00. Os resultados da detecção do fator corda estão prontos em 2 dias, ao passo que os de PRA necessitam de 4 dias. CONCLUSÕES: A identificação presuntiva de M. tuberculosis usando o aspecto macroscópico das colônias em conjunto com a detecção de fator corda por microscopia é um teste simples, rápido e de baixo custo. Recomendamos o teste de triagem combinado para rapidamente identificar M. tuberculosis em sítios com poucos recursos financeiros e em laboratórios menos equipados, enquanto se aguarda a identificação definitiva por métodos moleculares ou bioquímicos.

OBJECTIVE: The rapid differentiation between Mycobacterium tuberculosis and nontuberculous mycobacteria is fundamental for patients co-infected with tuberculosis and HIV. To that end, we use two methods in our laboratory: detection of cord factor and PCR-restriction enzyme analysis (PRA). The objective of this study was to evaluate the accuracy of a screening test on solid medium as a rapid method for the presumptive identification of M. tuberculosis complex, considering costs and turnover time. METHODS: A total of 152 strains were submitted to a combined screening test, consisting of the detection of cord factor under microscopy (Ziehl-Neelsen staining) and evaluation of the macroscopic aspect of colonies, as well as to PRA, which was used as the gold standard. Costs were estimated by calculating the price of all of the materials needed for each test. RESULTS: The overall accuracy of cord factor detection alone was 95.4% (95% CI: 90.7-98.1%), and that of the combined screening test was 99.3% (95% CI: 96.4-100%). Cord factor detection costs US$ 0.25, whereas the PRA costs US$ 7.00. Results from cord factor detection are ready in 2 days, whereas PRA requires 4 days to yield results. CONCLUSIONS: The presumptive identification of M. tuberculosis using the macroscopic evaluation of colonies combined with cord factor detection under microscopy is a simple, rapid and inexpensive test. We recommend the combined screening test to rapidly identify M. tuberculosis in resource-poor settings and in less well-equipped laboratories while awaiting a definite identification by molecular or biochemical methods.