Avaliação de diagnósticos do Mycobacterium spp. em populações diferencialmente susceptíveis

Abstract

Introduction. The diagnosis of paucibacillary forms of tuberculosis (TB), which mostly affects children, immunocompromised patients, transplanted and extra-pulmonary forms is limited by phenotypic techniques of smear and culture. Moreover, the diagnosis of mycobacteriosis, also has committed itself by the phenotypic methods. The polymerase chain reaction (PCR) and its variations, such as Nested-PCR (NPCR), has been described as promising techniques for rapid diagnosis of tuberculosis and mycobacteriosis. Objective. Evaluation of a NPCR protocol for detection of Mycobacterium tuberculosis in pulmonary and extrapulmonary anatomic sites of patients with clinical suspicion of TB. Subjects and Methods. Were included, prospectively, 24 pulmonary samples of 85 extrapulmonary, collected from 49 individuals HIV-seropositive and 28 HIV-seronegative and submitted to the gold standard method and NPCR targeting the transposon IS6110. Results. Tuberculosis was diagnosed in 11 patients (14,3%), with 54,5% of extrapulmonary forms and 45,5% pulmonary. The NPCR was positive in all, while the culture was positive in only seven of them. Smear positivity among the clinical specimens was 9,2%. The culture allowed the isolation of seven strains of M. tuberculosis and two M. avium complex (8,25%). The molecular positivity was described in 23,85% of samples. NPCR's performance against the culture, for pulmonary (n=22) and extrapulmonary samples (n = 83) was similar (100% sensitivity and specificity of approximately 83%). Positivity by NPCR was significantly greater than the isolation by culture among the extrapulmonary samples (p = 0,0042). Conclusions. The results suggest to perform further studies to corroborate the potential of NPCR-IS6110 for detection of mycobacterial genome in extrapulmonary TB, especially among immunocompromised. Furthermore, the detection of mycobacteria remains as diagnostic confirmation and the opportunity of investigation of the sensitivity profile, promoting effective treatment for any age and immune status.