Abstract
The digital polymerase chain reaction (dPCR) method is used to quantify the absolute numbers of genes by distributing the samples to each small well and performing PCR. To date, although there are several reports showing the usefulness of amplification of genes of pathogens in the diagnosis of pulmonary tuberculosis by dPCR, there have been only a few reports of genetic diagnosis for pulmonary Mycobacterium avium complex (pMAC) disease by the dPCR method. In this study, we compare the usefulness of the dPCR method in pMAC disease diagnosis using bronchial washing samples with the gold standard culture method and the TRC method. From March 2019 to February 2021, we recruited 135 patients in this study (mean age ± SD: 69.8 ± 10.1; males, 29; females, 106). We conducted dPCR, culture, and TRC methods using their bronchial washing samples and compared the concordance rates among the three. We also investigated the correlation between the number of dPCR-positive wells and the amount of acid-fast bacilli present in the sample smear. The concordance rate between the dPCR method and the culture method was 93% (sensitivity, 100%; specificity, 87%) and that between the dPCR method and the TRC method was 96% (sensitivity, 97%; specificity, 96%). The number of dPCR-positive wells was significantly correlated with smear samples from 0 to 3 Gaffky scale groups. The dPCR method for pulmonary MAC diagnosis has high sensitivity and the same detectability as the TRC method, which makes it useful for the diagnosis of pMAC disease.
