Presenter of 2 Presentations
O054 - A MOLECULAR ASSAY WITH INCREASED SENSITIVITY FOR IDENTIFYING COMMON BACTERIAL CAUSES OF PLEURAL EMPYEMA IN CHILDREN. (ID 504)
Abstract
Background
Pleural empyema is a serious complication of pneumonia in children. Negative bacterial cultures commonly impede optimal antibiotic stewardship. To improve bacterial identification, we developed a multiplex-qPCR for empyema and evaluated its performance compared with bacterial culture.
Methods
Our multiplex-qPCR assay targeting Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus and Haemophilus influenzae was first validated using n=267 laboratory-prepared (spiked) samples. We are recruiting 150 hospitalised children (<18yrs) with empyema for a clinical study in Melbourne, Australia. Pleural fluid specimens are examined by multiplex-qPCR and culture, and clinical sensitivity and time-to-identity compared to assess the potential ability multiplex-qPCR to reduce duration of empiric untargeted antibiotic therapy.
Results
Our multiplex-qPCR demonstrated 99.1% sensitivity and 100% specificity using spiked samples. From the first 50 clinical study participants, a bacterial pathogen was identified in 45/50 (90%) specimens by multiplex-qPCR, compared with 9/50 (18%) by culture (P<0.0001). S. pneumoniae (n=36) was the most common bacterial species identified, followed by S. pyogenes (n=6), H. influenzae (n=2) and S. aureus (n=1). Of the specimens found to contain S. pneumoniae by multiplex-qPCR, only 3/36 (8%) were also culture positive. We estimate our multiplex-qPCR would have reduced the duration of untargeted antibiotic therapy in 35/50 (70%) cases by a median 20 days (IQR 17-23).
Conclusions
Our multiplex-qPCR significantly improved detection of bacterial causes of empyema compared with culture, particularly for S. pneumoniae, and demonstrated potential to improve antibiotic stewardship. Findings suggest that multiplex-qPCR might benefit epidemiological studies of empyema and public health surveillance in addition to its utility for clinical diagnostics.
O074 - ASSESSING THE EARLY IMPACT OF PCV13 SCHEDULE CHANGE AND THE ROLE OF VIRAL COINFECTION IN PNEUMOCOCCAL EMPYEMA IN AUSTRALIAN CHILDREN (ID 779)
Abstract
Background
Streptococcus pneumoniae (pneumococcus) is the predominant cause of pleural empyema in children. Australia recently transitioned from a 3+0 to 2+1 schedule of 13-valent pneumococcal conjugate vaccine (PCV13). The impact on empyema-associated serotypes is unknown. Viral coinfection increases pneumococcal density, however the impact on frequency, pathogenesis and serotype aetiology is unclear. This study will evaluate the early impact of the PCV13 schedule change on empyema-associated pneumococcal serotypes and the role of viral co-infection.
Methods
We are recruiting 150 children and adolescents (<18yrs) with empyema, collecting pleural fluids, nasopharyngeal, and oropharyngeal swabs. Pneumococcal-positive samples will be identified using our recently developed multiplex-qPCR. Serotyping will be performed by pneumococcal TaqMan Array Cards, comparing serotypes before and after the PCV13 schedule change. Pleural fluids and swabs will be assessed by respiratory tract microbiota TaqMan Array Cards to determine frequency and aetiology of viral coinfection.
Results
Thus far, 36/50 (72%) pleural fluids were pneumococcus positive. Most (26/36, 72%) pneumococcal empyemas were caused by serotype 3. The percentage caused by serotype 3 increased from 20/29 (69%) in the 3+0 schedule era to 6/7 (86%) in the 2+1 schedule era (p = 0.1868, Fisher’s exact test). For patients with swabs available for testing, 10/22 (45%) had a viral coinfection, with Parainfluenza and Respiratory Syncytial Virus most prevalent.
Conclusions
Our project will investigate the epidemiology of empyema in a PCV13-vaccinated setting, and reveal the contribution of viruses to the pathogenesis of pneumococcal empyema. Our findings will be particularly relevant for countries considering transitioning from a 3+0 schedule to a 2+1 schedule.