Evaluation of droplet digital polymerase chain reaction by detecting cell-free deoxyribonucleic acid in pleural effusion for the diagnosis of tuberculous pleurisy: a multicentre cohort study

Clin Microbiol Infect. 2024 Sep;30(9):1164-1169. doi: 10.1016/j.cmi.2024.05.012. Epub 2024 May 27.

Abstract

Objectives: Tuberculous pleurisy is one of the most common types of extra-pulmonary tuberculosis, but the sensitivity of conventional mycobacterial culture (Culture) or Xpert MTB/RIF assay (Xpert) is not satisfying. This multicentre 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, 82.8-95.1%) in the definite tuberculous pleurisy group, which was significantly higher than those of Culture (57.1%, 60/105, 95% CI, 47.1-66.6%, p < 0.001), Xpert (46.7%, 49/105, 95% CI, 37.0-56.6%, p < 0.001), Ultra (69.5%, 73/105, 95% CI, 59.7-77.9%, p < 0.001) and real-time PCR (75.2%, 79/105, 95% CI, 65.7-82.9%, 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, 51.4-70.0%), which was still significantly higher than that of Ultra (27.4%, 31/113, 95% CI, 19.7-36.8%, p < 0.001) and real-time PCR (38.9%, 44/113, 95% CI, 30.0-48.6%, p < 0.001).

Discussion: 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.

Keywords: Cell-free DNA; Diagnosis; Droplet digital PCR; Pleural effusion; Tuberculous pleurisy.

Publication types

  • Multicenter Study
  • Evaluation Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Cell-Free Nucleic Acids*
  • China
  • Cohort Studies
  • DNA, Bacterial / genetics
  • Female
  • Humans
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis* / genetics
  • Mycobacterium tuberculosis* / isolation & purification
  • Pleural Effusion* / diagnosis
  • Pleural Effusion* / microbiology
  • Polymerase Chain Reaction / methods
  • Real-Time Polymerase Chain Reaction / methods
  • Sensitivity and Specificity*
  • Tuberculosis, Pleural* / diagnosis
  • Tuberculosis, Pleural* / microbiology
  • Young Adult

Substances

  • Cell-Free Nucleic Acids
  • DNA, Bacterial