Avaliação da virulência de isolados clínicos de Mycobacterium tuberculosis

Abstract

Mycobacterium tuberculosis infects one third of the population of the world. Almost 7 to 8 million of new cases are diagnosed, and 1.7 million of deaths are reported by year. The dissemination of clinical isolates demonstrates a great dispersion of clones, and may influence the transmission and possibly, the development of distinct clinical outcomes. This study aimed to evaluate the clonal relationship among the isolates, the susceptibility to antimicrobial agents, and the resistance to sodium nitrite of M. tuberculosis clinical strains from a previous epidemiological study to evaluate the transmission within close contacts. It was found that 36.8% (n=7) were resistant to nitrogen reactive species (percentage of viability varied from 17.1 to 114%). The susceptibility to six antimicrobials demonstrated that 42.1% (n=8) of isolates were resistant to at least one of the drugs and 15.7% (n=3) presented resistance to two or more drugs, demonstrating the circulation of extensive drug resistant phenotype (XDR). Most of the clinical strains (57.9%) was sensitive to 6 tested drugs. In relation to the molecular profile evaluated by MIRU and Spoligotyping, it was observed the inexistence of clones among the isolates. Although some strains were related to families already described as circulating in our country (LAM, LAM 3, LAM 6, LAM 9, Haarlem - H, Haarlem 1 - H1, Haarlem 3 - H3), some isolates were characterized within families never previously described in Brazil or Latin America (T1 e U), showing the dispersion and the emergency of distinct clones in Rio de Janeiro.