“SMART” digital nucleic acid amplification technologies for lung cancer monitoring from early to advanced stages

Evaluation of droplet digital PCR by detecting cell-free DNA in pleural effusion for the diagnosis of tuberculous pleurisy: a multicenter cohort study

OBJECTIVES

Tuberculous pleurisy is one of the most common extra-pulmonary tuberculosis, but the sensitivity of conventional mycobacterial culture (Culture) or Xpert MTB/RIF assay (Xpert) is not satisfying. This multicenter cohort study evaluated the accuracy of a new cell-free DNA droplet digital PCR assay (cf-ddPCR) for diagnosing Tuberculous pleurisy.

METHODS

Patients with suspected tuberculosis (≥ 5 years of age) with pleural effusion were consecutively recruited from nine research sites across six provinces in China between September 2020 to May 2022. Culture, Xpert, Xpert MTB/RIF Ultra assay (Ultra), real-time PCR and cf-ddPCR were performed simultaneously for all specimens.

RESULTS

A total of 321 participants were enrolled, and data from 281 (87.5%) participants were available, including 105 definite Tuberculous pleurisy, 113 possible Tuberculous pleurisy and 63 non-Tuberculous pleurisy according to the composite reference standard. The sensitivity of cf-ddPCR was 90.5% (95/105, 95% CI = 82.8% to 95.1%) in the definite Tuberculous pleurisy group, which was significantly higher than those of Culture (57.1%, 60/105, 95% CI = 47.1% to 66.6%, P<0.001), Xpert (46.7%, 49/105, 95% CI = 37.0% to 56.6%, P<0.001), Ultra (69.5%, 73/105, 95% CI = 59.7% to 77.9%, P<0.001) and real-time PCR (75.2%, 79/105, 95% CI: 65.7% to 82.9%, P < 0.001). In possible Tuberculous pleurisy, whose results of Culture and Xpert were both negative, the sensitivity of cf-ddPCR was 61.1% (69/113, 95% CI = 51.4% to 70.0%), which was still significantly higher than that of Ultra (27.4%, 31/113, 95% CI = 19.7% to 36.8%, P<0.001) and real-time PCR (38.9%, 44/113, 95% CI: 30.0% to 48.6%, P < 0.001).

CONCLUSIONS

The performance of cf-ddPCR is superior to Culture, Xpert, Ultra and real-time PCR, indicating that improved diagnostic accuracy can be anticipated by incorporating this new assay.

Establishment of Digital PCR Method and Reference Material for Adenoviruses 40 and 41

Coinfection with human adenovirus (HAdV) and SARS-CoV-2 has been associated with acute hepatitis in children with unknown etiology. Similar cases have been reported in many countries, and HAdV 40 and HAdV 41 have been identified. The quantification method is established based on digital PCR (dPCR) for HAdV 40/41, which is more convenient for low-concentration virus detection. The limit of detections of HAdV 40/41 dPCR were 4 and 5 copies/μL. Pseudovirus reference material (RM) that contains the highly conserved HEXON gene was developed and quantified with the dPCR method. The assigned values with expanded uncertainty were (1.43 ± 0.35) × 103 copies/μL for HAdV 40 RM and (1.21 ± 0.28) × 103 copies/μL for HAdV 41 RM. The values could be reproduced on multiple platforms. The dPCR method and pseudovirus RMs contribute to the improved accuracy of HAdV 40/41 detection, which is crucial for clinical diagnosis.