Abstract Rationale The microbiological diagnosis of pleural infection traditionally relies on the culture of pleural fluid or pleural tissue. However, there has been no formal prospective study that systematically compares the diagnostic yield of these specimen types. Methods In this prospective paired-design study, both pleural fluid and tissue specimens were obtained via medical thoracoscopy from patients with pleural infection. Specimens were cultured using both conventional methods and blood culture bottle systems. The primary outcome was culture positivity rate. Secondary outcomes included pathogen distribution, time to culture positivity, bacterial load by quantitative PCR, and the characterization of the microbial community through 16S rRNA sequencing. Results Complete outcome data were available for 61 patients (98.4%). Pleural fluid cultures yielded significantly higher positivity rates than pleural tissue cultures (57.4% vs 32.8%; difference 24.6%, 95% CI 8.5% to 34.0%). This superiority was particularly pronounced with blood culture bottle systems, where pleural fluid yielded higher positivity than tissue (54.1% vs 27.9%; difference 26.2%, 95% CI 9.9% to 35.6%, p = 0.002). Pleural fluid demonstrated significantly higher bacterial load (median 4.94 × 109 vs 8.79 × 107 copies/μL, p 0.001), shorter time to positivity (median 10.8 vs 20.3 hours, p = 0.008), and greater relative abundance of anaerobic bacteria (45.7% vs 29.6%; log2 fold change 1.24, 95% CI 0.24 to 2.23, FDR=0.04). Conclusion In patients with pleural infection, pleural fluid yielded significantly higher culture positivity rates than pleural tissue when both specimens were obtained via medical thoracoscopy, particularly when using blood culture bottle systems. This abstract is funded by: Non-communicable Chronic Diseases-National Science and Technology Major Project
Zhou et al. (Fri,) studied this question.