Performance Assessment of the GenoType MTBDR sl Test and DNA Sequencing for Detection of Second-Line and Ethambutol Drug Resistance among Patients Infected with Multidrug-Resistant Mycobacterium tuberculosis

Abstract

The GenoType MTBDRsl test and DNA sequencing were used to rapidly detect second-line drug-and ethambutol (EMB)-resistant Mycobacterium tuberculosis. The ability of these two assays to detect the presence of mutations associated with resistance to fluoroquinolones (FLQ), aminoglycosides/cyclic peptide (AG/CP), and EMB in the gyrA, rrs, and embB genes (for the GenoType MTBDRsl test) and gyrA, gyrB, rrs, eis, embC, embA, embB, and embR genes (for DNA sequencing) was compared to that of conventional agar proportion drug susceptibility testing (DST). We evaluated 234 multidrug-resistant (MDR) M. tuberculosis isolates. The two molecular methods had high levels of specificity (95.8 to 100%). The sensitivities for FLQ resistance detection for both methods were 85.1%. For AG (kanamycin [KM] and amikacin [AM]) and CP (capreomycin CAP]), the sensitivities of resistance detection using the GenoType MTBDRsl test were 43.2%, 84.2%, and 71.4%, respectively, while with the inclusion of an extra gene, eis, in sequencing, the sensitivity reached 70.3% for detection of KM resistance. The sensitivities of EMB resistance detection were 56.2% and 90.7% with the GenoType MTBDRsl test and sequencing, respectively. We found that the GenoType MTBDRsl test can rapidly detect resistance to FLQ, CAP, and AM. The accuracy of the GenoType MTBDRsl test for the detection of FLQ and AM resistance was comparable to that of conventional DST; however, the test was less accurate for the detection of KM and EMB resistance and demonstrated a poor predictive value for CAP resistance. We recommend including new alleles consisting of the eis promoter and embB genes in molecular analysis. However, conventional DST is necessary to rule out false-negative results from molecular assays.

Performance Assessment of The Polymerase Chain Reaction-restriction Fragment Length Polymorphism Method for Rapid Detection of Susceptibility to Ethambutol and Molecular Prediction of XDR Tuberculosis in Clinical Isolates of Mycobacterium Tuberculosis

“…Among the 72 sensitive strains without mutations in codon 306, three isolates had a mutation in codons 297 and 328 (10). Adaptation rate between phenotypic assessment of culture and two genotypic assays for resistance to EMB was 68.4% by GenoType MTBDRs1 kit and 92.3% with sequencing.…”

Rapid Diagnosis of Mycobacterium tuberculosis Infection and Drug Susceptibility Testing

“…In the most recent evaluation of this assay it was compared against DNA sequencing and was found to accurately detect resistance to amikacin and fluoroquinolones (although only ofloxacin was tested by conventional susceptibility testing). 45 In contrast, the method was not as sensitive for detecting resistance to kanamycin or ethambutol, and had a poor predictive value for detecting resistance to capreomycin. 45 Because of the worsening global burden of MDR-TB and extensively drugresistant TB, methods that can be used to test for resistance to second-line antituberculous drugs should receive emphasis for research and development as well as for clinical trials.…”

“…[43][44][45] Evaluations of this assay have shown variable results. In the most recent evaluation of this assay it was compared against DNA sequencing and was found to accurately detect resistance to amikacin and fluoroquinolones (although only ofloxacin was tested by conventional susceptibility testing).…”

Evaluation of the BACTEC MGIT 960 SL DST Kit and the GenoType MTBDRsl Test for Detecting Extensively Drugresistant Tuberculosis Cases

“…Our sensitivity rates may rise if we use this new version. Therefore, low sensitivity for KAN may have depended on resistant TB strains containing different genetic regions [23,24].…”