Multidrug-resistant tuberculosis: rapid molecular detection with MTBDRplus assay in clinical samples

Nowadays, the greatest concern of tuberculosis control programmes is the appearance of multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis. Rapid determination of drug resistance in clinical samples, with Mycobacterium tuberculosis complex (MTC), is the prerequisite for initiating effective chemotherapy, ensuring successful treatment of the patient and preventing further spread of drug-resistant isolates. The aim of our study was to determine the sensitivity of the new MTBDRplus assay in comparison to culture, identification and classic DST, directly from smear-positive clinical specimens. A total of 68 smear-positive sputum specimens were processed by both the classical mycobacteriological methods and the molecular assay, MTBDRplus. MTBDRplus assay allowed an accurate identification of MTC species by detection of the specific band in all samples, from which we also isolated and identified MTC strains by culture methods. In the samples from which we isolated susceptible strains (63.2%), wild type patterns were found using MTBDRplus assay. The samples from which we isolated resistant strains (36.8%) showed specific mutations associated with the correspondent resistant phenotype. Our study indicated that this assay allows rapid detection of resistance, always in agreement with classic methods.