Molecular method improves bacterial identification in paediatric pleural empyema.

Introduction/Aim: Pleural empyema is a serious complication of bacterial pneumonia. Affected children often require surgical intervention to drain purulent pleural fluid (PF) and empiric IV antibiotics. Identifying the bacterial cause of empyema by culturing this PF is unreliable, especially with prior antibiotic use. In most cases, the bacterial cause remains unidentified, necessitating prolonged empiric antibiotics, increasing risk of side-effects and antimicrobial resistance. We are developing a multiplex quantitative PCR assay (m-qPCR) to improve identification of the bacterial causes of empyema, to direct rational antibiotic therapy. Method(s): We are recruiting 150 paediatric empyema patients, across two tertiary hospitals in Melbourne, and testing PF using our m-qPCR assay. The m-qPCR targets the most common causes of empyema: Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus and Haemophilus influenzae. We will compare our m-qPCR assay's performance against identification by PF culture and assess its potential clinical impact. Result(s): We have recruited and tested PF from 50 empyema patients, aged between 1.5 months and 17 years old. Using our m-qPCR, we detected a bacterial species in 45/50 (90%), compared with 9/50 (18%) by PF culture. Our assay showed 100% concordance for target species with culture results. By m-qPCR, the most common pathogen was S. pneumoniae n=36 (72%), followed by S. pyogenes in n=6 (12%), H. influenzae in n=2 (4%) and S. aureus in n=1 (2%). Conclusion(s): Preliminary results show our m-qPCR is 5-fold more sensitive than PF culture in identifying the bacterial cause of pleural empyema. We will further assess the performance of our m-qPCR, and its potential clinical impact as a rapid, reliable diagnostic, enabling efficient antibiotic stewardship and improved clinical outcomes for patients.