Droplet digital PCR (ddPCR) is a technology that has higher sensitivity over real-time PCR in the identification of trace DNA. However, the use of ddPCR for the detection of Mycobacterium tuberculosis (MtB) DNA in pathological samples has not been fully studied.
A total of 65 formalin-fixed and paraffin-embedded (FFPE) specimens were involved in this study, 20 samples with definite results of tuberculosis (TB) were used to establish the ddPCR system for TB detection; then ddPCR was conducted to detect TB DNA in the 45 patients that were “possible TB” (real-tme PCR results in “Grey area”, Ziehl-Neelsen staining (-) and HE staining (suspicious morphology of tuberculosis)). The clinical treatment and disease outcomes were followed to assess the accuracy of ddPCR in the detection of TB DNA.
Among the 45 samples that were “possible TB”, 26 samples were ddPCR-positive, 12 samples were ddPCR-negative, and 7 samples were in the gray area. ddPCR improved the positive rate of 57.8% (26/45) for the samples that were “in the gray area” of real-time PCR. Moreover, several patients received the anti-tuberculosis therapy, the effective ratio of the therapy of ddPCR-positive, ddPCR-negative, ddPCR-“gray area” was 61.9% (13/21), 50.0% (2/4) and 33.3% (1/3), respectively.
ddPCR is more sensitive for detecting mild TB via FFPE samples than real-time PCR. The ddPCR methods can add additional value to the diagnosis of TB from pathological samples.

Copyright © 2020. Published by Elsevier Ltd.