Performance of the Quantamatrix Multiplexed Assay Platform system for the differentiation and identification of Mycobacterium species.

Purpose. The purpose of this study was to evaluate the usefulness of a new diagnostic multiplexed bead-based bioassay (Quantamatrix Multiplexed Assay Platform; QMAP) system with shape-encoded silica microparticles for the rapid and accurate detection and identification of 23 mycobacterial species/groups, including Mycobacterium tuberculosis complex (MTBC). Methodology. A total of 295 mycobacterial clinical isolates cultured from respiratory specimens were used for identification of MTBC and non-tuberculous mycobacteria (NTM) using the QMAP system and the results were confirmed with PCR-restriction fragment length polymorphism (RFLP) analysis of the rpoB gene, rpoB sequence analysis and PCR-reverse blot hybridization assay (REBA). Results/Key findings. The Mycobacterium genus-specific probe of the QMAP system was positive for all 46 Mycobacterium reference strains and negative for 59 non-Mycobacterium strains. Based on 295 liquid culture-positive samples, both the culture-based conventional identification method and the QMAP system identified each 212 and 81 isolates as MTB and NTM species. The concordance rates for the identification of NTM species between the QMAP system and molecular assays were 92.8% (77/83), 97.6% (81/83) and 100% (83/83) for PCR-RFLP, the rpoB sequence analysis and PCR-REBA, respectively. Conclusion. The QMAP system yielded rapid, highly sensitive and specific results for the identification of MTBC and NTM and accurately discriminated between NTM species within 3 h.