Resumo

Tuberculosis (TB) and multidrug & extensively drug-resistant (DR) TB are important public health problems which are spreading worldwide. The aims of this study were to determine the sensitivity and specificity of the GenoType® MTBBDRplus assay from clinical strains and to explore its possible application in routine work. Clinical samples were previously decontaminated using NaOH-N-acetyl-L-cystein for Ziehl-Neelsen staining and cultures. The leftover sediments of smear-positive samples were stored at 30 ºC, 18 of which were selected to be included in this study according to the patients who had treatment failure or relapse in an outpatient routine setting at Brazilian Middle West Region. A comparison of the performances of GenoType® MDRTBplus and BACTEC MGIT 960 SIRE methods was made regarding drug resistance, and just one disagreement between the methods was observed. Among the 18 clinical isolates of Mycobacterium tuberculosis Complex, 2 of them showed resistance to rifampicin, 1 showed resistance to isoniazid and 2 to isoniazid and rifampin by GenoType® MDRTBplus. When using the BACTEC MGIT 960 SIRE it was detected only 1 clinical isolate with resistance to isoniazid. The genotype allowed us to assess the mutations present in the rpoB, katG and inhA genes. It was observed mutations in the rpoBD516V 5,5% (1/18), rpoBH526Y 5.5% (1/18), rpoBS531L 11.1% (2/18), katGS315T 5.5% (1/18), inhA C-15T 5.5% (1/18) and inhAA16G 11.1% (2/18). 94.4% concordance between the GenoType® assay and BACTEC MGIT was obtained. GenoType® MTBDRplus has demonstrated to be easy to implement and perform in clinical laboratories, being useful for a rapid detection of DR,M. tuberculosis clinical isolates. Therefore, this assay could be applied as a rapid tool to predict INH-R and/or RIF-R in DR risk cases.