Purpose: Genotypic methods have considerably improved the diagnosis of multidrug-resistant (MDR) tuberculosis. One of these tests is Anyplex II MTB/MDR/XDR (Anyplex). Our aim was to evaluate the diagnostic performance of this multiplex PCR.
Methods: We conducted our study on 47 MDR tuberculosis and 14 pan-susceptible strains. We evaluated the ability of Anyplex to detect resistance mutations in rpoB (rifampin [RIF]), katG and inhA (isoniazid [INH]), gyrA (fluoroquinolones [FLQ]), and rrs and eis (aminoglycosides [AMG]). We used the agar proportion method as gold standard. We also studied concordance with GenoType MTBDRplus (first line drugs) and MTBDRsl (second line drugs). DNA sequencing was applied to clarify discrepancies.
Results: All pan-susceptible strains were susceptible by Anyplex. Sensitivity and specificity of Anyplex for detection of resistance mutations were 97.9% and 100%, respectively, for RIF, 91.5% and 100% for INH, 80% and 100% for FLQ, and 50% and 99.7% for AMG. Concordance with GenoType was perfect for RIF, INH, and FLQ (kappa score, k=1.0) and moderate for AMG (k=0.48). Sensitivity and specificity for detection of MDR tuberculosis were 89.4% and 100%, respectively. DNA sequencing of the phenotypically resistant strains considered as susceptible by Anyplex, confirmed no mutations in the corresponding genes.
Conclusions: Anyplex is a reliable assay for the detection of MDR tuberculosis and shows excellent concordance with GenoType. Anyplex reduces the time to diagnosis of MDR tuberculosis strains, as it is recommended by current guidelines on control of tuberculosis.
Keywords: Anyplex II MTB/MDR/XDR; Molecular diagnostic methods; Multiplex PCR; Mycobacterium tuberculosis; Resistance mutations.
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