Improved detection of isoniazid-heteroresistant Mycobacterium tuberculosis subpopulations by droplet digital PCR compared to MeltPro TB assay.

UNLABELLED: Drug resistance in Mycobacterium tuberculosis (Mtb), especially isoniazid (INH) resistance, challenges tuberculosis control. This study evaluated droplet digital PCR (ddPCR) against the traditional MeltPro TB assay. A total of 77 INH-resistant samples from Beijing Chest Hospital, China, underwent ddPCR, drug susceptibility testing, and Sanger sequencing. Of the 73 valid samples, MeltPro detected 55 INH-resistant and 18 heteroresistant samples; ddPCR found 55 high-frequency mutations, 11 of the 18 heteroresistant by MeltPro as heteroresistant, and 6 of the 7 below limit as sensitive, 1 as Nocardia. Using ddPCR as a secondary screening tool for MeltPro results can screen false positives in MeltPro, improving INH resistance detection accuracy (98.63% vs. 89.04%). DdPCR technology performs excellently in tuberculosis drug resistance detection and provides strong technical support for the accurate diagnosis and treatment of tuberculosis.

IMPORTANCE

Tuberculosis has emerged as a significant threat to global health, bringing numerous new cases and a large number of deaths annually. Isoniazid (INH), as a first-line treatment drug, plays a crucial role. However, the emergence of its drug resistance poses a tough challenge for tuberculosis control. Currently, the methods for detecting INH resistance and heteroresistance have limitations like the slow speed of traditional culture tests and the insufficient sensitivity of molecular methods. Therefore, improving the diagnostic efficacy of the detection results for INH resistance is crucial for the treatment of tuberculosis.