Rapid Triage of Smear-Positive Tuberculosis Suspects with a Commercial DNA Microarray: A Real-World Experience from 1100 Sputum Specimens.

OBJECTIVE

To evaluate the real-world utility of a commercial DNA microarray assay for early triage of Mycobacterium tuberculosis complex (MTBC) in smear-positive sputum specimens.

METHODS

This retrospective single-center study analyzed 1100 smear-positive sputum specimens submitted to Guangzhou Chest Hospital between January 2019 and December 2023. All specimens were processed in parallel using MGIT960 liquid culture and DNA microarray testing. For a subset of MGIT960 culture-positive specimens, MPT64 antigen testing was performed as per routine clinical practice for species identification. The study initially described the distribution of species identification results by microarray. Subsequently, in a subset of specimens with both microarray and MPT64 results (n=68), the agreement between the two assays in MTBC identification was evaluated using MPT64 as the reference standard.

RESULTS

The DNA microarray provided species-level identification of mycobacteria in the smear-positive specimens, with MTBC detected in 41.4% (455/1100) of cases. In the comparative analysis with MPT64 results, the microarray demonstrated 100% sensitivity (95% CI: 83.2-100.0), 97.9% specificity (95% CI: 88.7-99.9), and a Cohen's kappa coefficient of 0.97 for MTBC identification.

CONCLUSION

In a real-world setting, the DNA microarray assay demonstrates high reliability for MTBC identification while simultaneously providing species-level information for non-tuberculous mycobacteria (NTM). This capability allows the microarray assay to serve as an effective triage tool for smear-positive sputum specimens, offering species-level differentiation between tuberculosis and NTM infections, with the potential to reduce reliance on additional phenotypic confirmation pending further validation.