The role of molecular diagnostics in pleural empyema: insights from a 4-year analysis of microbial trends and antimicrobial use

<b>Introduction.</b> Pleural empyema is common but microbiological diagnosis is challenging, often leading to prolonged empiric broad-spectrum antimicrobial use.<b>Hypothesis.</b> 16S rRNA PCR on operative pleural tissue will increase diagnostic yield and improve antibiotic stewardship in patients with surgically managed pleural empyema.<b>Aim.</b> The objective was to characterize the clinical and microbiological characteristics of surgically managed pleural empyema, assess the diagnostic yield of 16S rRNA PCR and determine its impact on antimicrobial use.<b>Methodology.</b> This retrospective study identified patients with pleural empyema at a tertiary thoracic referral unit in North London, UK, between March 2019 and March 2023. Demographic, clinical and microbiological characteristics were collected.<b>Results.</b> One hundred eighty-three patients underwent surgery for pleural empyema at University College Hospital at Westmoreland Street over a 4-year period. Most empyemas were community-acquired, and the main surgical modality was minimally invasive video-assisted thoracoscopic surgery (151/183, 82.5%). Thirty-day all-cause post-operative mortality was 0.6%. Microbial aetiology was ascertained in 47%, with <i>Streptococcus anginosus</i> group, <i>Streptococcus pneumoniae</i> and anaerobes most frequently identified. Operative pleural tissue 16S rRNA PCR had a high diagnostic yield compared to conventional culture alone (68.2% vs. 26.4%). Post-operatively, antibiotics were prescribed for a median of 14 days (interquartile range 10-18), the majority broad spectrum (169/181, 93.4%). 16S PCR impacted antimicrobial prescribing in one-tenth of cases when used (4/32, 12.5%); however, turnaround times limited its impact.<b>Conclusion.</b> Molecular diagnostics improve bacterial detection and antibiotic stewardship in pleural empyema. Streamlining molecular diagnostics pathways or developing pleural-specific multiplex PCR panels could further enhance management.