Broad-range bacterial polymerase chain reaction in the microbiologic diagnosis of complicated pneumonia

BACKGROUND: A bacterial cause is not frequently identified in children with pneumonia complicated by parapneumonic effusion (ie, complicated pneumonia). OBJECTIVES: To determine the frequency of positive blood and pleural fluid cultures in children with complicated pneumonia and to determine whether broad-range 16S rRNA polymerase chain reaction (PCR) improves identification of a microbiologic cause. METHODS: This prospective cohort study included children 1-18 years of age hospitalized with complicated pneumonia. RESULTS: Pleural fluid drainage was performed in 64 (51.6%) of 124 children with complicated pneumonia. A microbiologic cause was identified in 11 of 64 patients (17.2%; 95% confidence interval [CI]: 8.9%-28.7%). Bacteria were isolated from pleural fluid culture in 6 of 64 patients (9.4 %; 95% CI: 3.5%-19.3%) undergoing pleural drainage; the causative bacteria were Staphylococcus aureus (n = 5) and Streptococcus pneumoniae (n 1). Blood culture identified a bacterial cause in 3 of 44 cases (6.8%; 95% CI: 1.4%-18.7%) undergoing pleural fluid drainage; S. pneumoniae (n = 1), Haemophilus influenzae (n 1), and S. aureus (n = 1) were isolated. Only 3 of the 19 pleural fluid samples (15.8%; 95% CI: 3.4%-39.6%) analyzed with 16S rRNA PCR were positive. S. pneumoniae was the only organism detected in all three samples; two of these three had negative pleural fluid cultures and absence of bacteria on Gram stain. S. aureus was isolated from pleural fluid culture in one patient with a negative 16S rRNA PCR test. CONCLUSIONS: Causative bacteria were infrequently identified in children with complicated pneumonia. Broad-range 16S rRNA PCR only modestly improved the microbiologic yield over conventional culture methods. Journal of Hospital Medicine 2012;7:8-13. (C) 2011 Society of Hospital Medicine