Evaluation of the GenoType MTBDRplus and MTBDRsl for the detection of drug-resistant Mycobacterium tuberculosis on isolates from Beijing,China
The incidence of tuberculosis (TB) and especially multidrug-resistant TB (MDR) and extreme drug resistance (XDR-TB) continue to increase alarmingly worldwide and reliable and fast diagnosis of MDR-TB and XDR-TB is essential for the adequate treatment of patients. So molecular line probe assays (LPAs) for detection of MDR-TB and XDR-TB have been endorsed by the World Health Organization (WHO). We analyzed 96 isolates from Beijing comparing culture-based drug susceptibility testing (DST) to LPAs detecting rifampicin (RFP), isoniazid (INH), and levofloxacin (LFX), amikacin (AM), capreomycin (CMP), ethambutol (EMB) resistance. Compared to phenotypic DST, the GenoType MTBDRplus and MTBDRsl showed a sensitivity of 98.7% and a specificity of 88.9% for detection of RFP resistance, 82.1% and 94.4% for INH, 89.7% and 94.4% for LFX, 60.0% and 98.7% for AM/CPM, 57.5% and 98.2% for EMB, respectively. The sensitivity and specificity of LPAs for MDR-TB and XDR-TB were 80.8%, 100% and 50.0%, 97.6%. Mutations in codon S531L of the rpoB gene and S315T1 of KatG gene were dominated in MDR-TB strains. The most frequently observed mutations were in codon A90V of the gyrA gene, A1401G of the rrs gene and M306V of the embB gene, according to the MTBDRsl results. Our study showed that, in combination to phenotypic DST, application of the LPAs might be an efficient and reliable supplementary DST assay for rapid susceptibility screening of MDR-TB and XDR-TB. Using LPAs in high MDR/XDR burden countries allows for appropriate and timely treatment, which will reduce transmission rates, morbidity and improve treatment outcomes in patients.