OBJETIVO: Analisar e comparar as mutações em duas regiões diferentes do gene katG, responsáveis pela resistência à isoniazida (INH). MÉTODOS: As análises foram feitas em 97 cepas de Mycobacterium tuberculosis multirresistentes isoladas de culturas de escarro provenientes do Centro de Referência Professor Hélio Fraga. Outras 6 cepas, sensíveis à INH, não apresentaram mutações e foram incluídas como controle. Duas regiões do gene katG (GenBank nº de acesso U06258) - região 1, do códon 1 até o códon 119, e região 2, do códon 267 até o códon 504 - foram amplificadas por PCR e sequenciadas para a identificação das mutações. RESULTADOS: Sete cepas eram resistentes à INH e não mostraram mutação nas duas regiões. Trinta cepas apresentaram mutações na região 1, que se caracterizou por um grande número de deleções, especialmente no códon 4 (24 cepas). A região 2 mostrou 83 mutações pontuais, principalmente no códon 315, com 73 casos de troca de serina (AGC) para treonina (ACC). A análise da região 2 permitiu o diagnóstico de resistência à INH em 81,4% das cepas. Nove cepas tiveram mutações somente na região 1, e isso permitiu o aumento de identificação de cepas resistentes à INH para 90,6%. CONCLUSÕES: O número de mutações do códon 315 foi elevado, compatível com os casos descritos no Brasil e em outros países, e a análise da região 1 aumentou a detecção de mutações em mais 9,2%.

OBJECTIVE: To analyze and compare the mutations in two different regions of the katG gene, which is responsible for isoniazid (INH) resistance. METHODS: We analyzed 97 multidrug-resistant Mycobacterium tuberculosis strains isolated in cultures of sputum samples obtained from the Professor Hélio Fraga Referral Center, in Brasília, Brazil. Another 6 INH-sensitive strains did not present mutations and were included as controls. We used PCR to amplify two regions of the katG gene (GenBank accession no. U06258)-region 1, (from codon 1 to codon 119) and region 2 (from codon 267 to codon 504)-which were then sequenced in order to identify mutations. RESULTS: Seven strains were resistant to INH and did not contain mutations in either region. Thirty strains carried mutations in region 1, which was characterized by a high number of deletions, especially at codon 4 (24 strains). Region 2 carried 83 point mutations, especially at codon 315, and there was a serine-to-threonine (AGC-to-ACC) substitution in 73 of those cases. The analysis of region 2 allowed INH resistance to be diagnosed in 81.4% of the strains. Nine strains had mutations exclusively in region 1, which allowed the proportion of INH-resistant strains identified to be increased to 90.6%. CONCLUSIONS: The number of mutations at codon 315 was high, which is consistent with cases described in Brazil and in other countries, and the analysis of region 1 resulted in a 9.2% increase in the rate at which mutations were identified.

OBJETIVO: Analisar as características clínicas e a evolução de um grupo de pacientes com culturas de escarro positivas para Mycobacterium tuberculosis multirresistente (MR) e tratados em um centro de referência no município do Rio de Janeiro. MÉTODOS: A partir dos resultados de M. tuberculosis MR em culturas de escarro, foram selecionados 50 pacientes cujos dados clínicos foram obtidos através do Banco de Dados TBMR do Ministério da Saúde. Foram considerados a frequência de abandono, as recidivas, as falências e os tratamentos prévios para TB até o diagnóstico de TBMR. O padrão radiológico foi classificado em uni- ou bilateral, e cavitário ou não. Dois anos após o término do tratamento padronizado para TBMR, o desfecho (cura, falência, abandono ou óbito) de cada paciente foi avaliado e repetido a cada dois anos. O período de seguimento foi de oito anos após o tratamento. RESULTADOS: A média do número de tratamentos prévios foi de 2,3 ± 0,9. O tempo médio entre o diagnóstico inicial e o desenvolvimento de TBMR foi de 2 ± 1,7 anos. Após dois anos do tratamento inicial para TBMR houve 2 abandonos, 8 óbitos, 18 curas e 22 falências. A análise bivariada mostrou que o comprometimento pulmonar bilateral e o padrão cavitário reduziram acentuadamente a chance de cura, com risco relativo de 1-0,6 (40%) e 1-0,7 (30%), respectivamente. Ao final do seguimento, houve 2 abandonos, 9 falências, 17 curas e 22 óbitos. CONCLUSÕES: O comprometimento pulmonar bilateral e lesões cavitárias reduziram a possibilidade de cura dos pacientes com TBMR. A maioria dos pacientes com falha de tratamento evoluiu para óbito no período de 8 anos.

OBJECTIVE: To analyze the clinical characteristics and evolution of a group of patients with positive sputum cultures for multidrug-resistant (MDR) Mycobacterium tuberculosis and treated at a referral center in the city of Rio de Janeiro, Brazil. METHODS: Based on the positive results in sputum cultures for MDR M. tuberculosis, 50 patients were selected, and their clinical data were obtained from the Brazilian Ministry of Health MDR-TB Database. The frequencies of noncompliance, relapses, failures and previous treatments for TB up to diagnosis of MDR-TB were compiled. The radiological patterns were classified as unilateral or bilateral, and with or without cavitation. Two years after the end of the standard treatment for MDR-TB, the outcome (cure, failure, noncompliance or death) for each patient was evaluated and reassessed every two years. The post-treatment follow-up period was eight years. RESULTS: The mean number of previous treatments was 2.3 ± 0.9. The mean interval between the initial diagnosis and the development of MDR-TB was 2.0 ± 1.7 years. Two years after the initial treatment for MDR-TB, 2 patients had abandoned treatment, 8 had died, 18 had been cured, and 22 had presented treatment failure. The bivariate analysis showed that bilateral pulmonary involvement and cavitary pattern markedly reduced the chances for cure, with a relative risk of 1-0.6 (40%) and 1-0.7 (30%), respectively. At the end of the follow-up period, 2 patients had abandoned treatment, 9 had presented treatment failure, 17 had been cured, and 22 had died. CONCLUSIONS: Bilateral pulmonary involvement and cavity pattern greatly reduced the chances for cure of the patients with MDR-TB. Most patients who presented treatment failure died within the 8-year follow-up period.

In order to evaluate the Organon Teknika MB/BacT system used for testing indirect susceptibility to the alternative drugs ofloxacin (OFLO), amikacin (AMI), and rifabutin (RIF), and to the usual drugs of standard treatment regimes such as rifampin (RMP), isoniazid (INH), pyrazinamide (PZA), streptomycin (SM), ethambutol (EMB), and ethionamide (ETH), cultures of clinical specimens from 117 patients with pulmonary tuberculosis under multidrug-resistant investigation, admitted sequentially for examination from 2001 to 2002, were studied. Fifty of the Mycobacterium tuberculosis cultures were inoculated into the gold-standard BACTEC 460 TB (Becton Dickinson) for studying resistance to AMI, RIF, and OFLO, and the remaining 67 were inoculated into Lowenstein Jensen (LJ) medium (the gold standard currently used in Brazil) for studying resistance to RMP, INH, PZA, SM, EMB, and ETH. We observed 100% sensitivity for AMI (80.8-100), RIF (80.8-100), and OFLO (78.1-100); and 100% specificity for AMI (85.4-100), RIF (85.4-100), and OFLO (86.7-100) compared to the BACTEC system. Comparing the results obtained in LJ we observed 100% sensitivity for RMP (80-100), followed by INH - 95% (81.8-99.1), EMB - 94.7% (71.9-99.7), and 100% specificity for all drugs tested except for PZA - 98.3 (89.5-99.9) at 95% confidence interval. The results showed a high level of accuracy and demonstrated that the fully automated, non-radiometric MB/BacT system is indicated for routine use in susceptibility testing in public health laboratories.

In order to evaluate the direct-method test of sensitivity to drugs used in the principal tuberculosis treatment regimes, in the Organon Teknika MB/BacT system, we tested 50 sputum samples positive to microscopy taken from patients with pulmonary tuberculosis and with clinical indications for an antibiogram, admitted sequentially for examination during the routine of the reference laboratory. The material was treated v/v with 23% trisodium phosphate solution, incubated for 24 h at 35°C, and neutralized v/v with 20% monosodium phosphate solution. The material was then centrifuged and the sediment inoculated into flasks containing Rifampin - 2 µg/ml, Isoniazid - 0.2 µg/ml, Pyrazinamide - 100 µg/ml, Ethambutol - 2.5 µg/ml, Ethionamide - 1.25 µg/ml, and Streptomycin - 2 µg/ml. The tests were evaluated using the indirect method in the BACTEC 460 TB (Becton Dickinson) system as the gold standard. The results showed that the Rifampin test performed best, i.e., 100% sensitivity at 95% Confidence Interval (82.2-100) and 100% specificity at 95% Confidence Interval (84.5-100), followed by Isoniazid and Pyrazinamide. In this experiment, 92% of the materials showed a final reading in 30 days; this period represents the time for primary isolation as well as the results of the sensitivity profile, and is within Centers for Disease Control and Prevention recommendations regarding time for performance of the antibiogram. The inoculated flasks showed no contamination during the experiment. The MB/BacT is shown to be a reliable, rapid, fully automated nonradiometric system for the tuberculosis antibiogram.

We used a slide culture technique to detect tubercle bacilli surviving in sputum smears (n=46) after conventional heat fixation and Ziehl-Neelsen staining. In all heat-fixed sputum smears, tubercle bacilli survived after time 0 (n=22), 24 h (n=7), 48 h (n=7), 72 h (n=4), and seven days (n=6). None of the stained sputum smears showed growth on slide cultures. Viable tubercle bacilli remaining in heat-fixed sputum smears for at least seven days may present an infection risk to laboratory staff. Thus, sputum smears should be stained immediately by the Ziehl-Neelsen method or stored in a safe container to avoid transmission of tuberculosis.