First evaluation in Argentina of the GenoType® MTBDRplus assay for multidrug-resistant Mycobacterium tuberculosis detection from clinical isolates and specimens

IMPERIALE BELÉN; ZUMÁRRAGA MARTÍN ; WELTMAN GABRIELA; ZUDIKER ROXANA; CATALDI ANGEL; MORCILLO NORA

REVISTA ARGENTINA DE MICROBIOLOGíA

ASOCIACION ARGENTINA MICROBIOLOGIA

Lugar: Buenos Aires; Año: 2012 vol. 44 p. 283 - 289

0325-7541

Tuberculosis (TB) and multidrug and extensively drug-resistant (DR) TB, are important public health problems that are spreading worldwide. The aims of this study were to determine the sensitivity and specificity of the GenoType® MTBDRplus assay from smear-positive clinical specimens and isolates; and to explore its possible application in routine work. Clinical samples were decontaminated for Ziehl-Neelsen stains and cultures using NaOH-N-acetyl-L-Cystein or NaOH-ClNa hypertonic solution. The leftover sediments of the smear-positive samples were stored at ?20ºC, and 70 of them were selected to be included in this study according to their DR profile. Thirty DR M. tuberculosis isolates were also assessed. Sequencing was used as gold standard to detect mutations conferring isoniazid (INH) and rifampicin (RIF) resistance. Valid results were obtained in 94.0% of the samples, and 85.5% (53/62) of the INH-R samples were properly identified. Mutations in katGS315T gene and inhA C-15T gene promoter were present in 59.7% (37/62) and 25.8% (16/62) of the INH-R samples respectively. The system could also identify 97.7% (41/42) of the RIF-R samples; the mutations found were rpoBS531L (66.7%, 28/42), D516V (19.0%, 8/42), H526Y and S531P/W (4.8%, 2/42) and the S522L/Q (2.4%, 1/42). A concordance of 98.8% between GenoType and sequencing was obtained. GenoType® MTBDRplus has demonstrated to be easy to implement and to perform in clinical laboratories and useful for a rapid detection of DR M. tuberculosis from decontaminated sputa and clinical isolates. Therefore, this assay could be applied, as a rapid tool to predict INH-R and/or RIF-R in DR risk cases.