DNA bacterial load in children with bacteremic pneumococcal community-acquired pneumonia

This study was conducted to evaluate the association between pneumococcal DNA load and parapneumonic pleural effusion (PPE) in children with community-acquired pneumonia. Bacterial load was quantified and related to the presence of PPE with or without empyema in 72 otherwise healthy children aged ≤5 years who were hospitalised because of radiographically confirmed CAP and showed a real-time polymerase chain reaction that was positive for Streptococcus pneumoniae. The proportion of children with a high bacterial load (i.e. ≥265 DNA copies/mL) was larger among the subjects with PPE than those without it. Multivariate analysis showed that a high bacterial load was significantly associated with PPE (OR 8.65; 95% CI 1.10-67.8 vs a bacterial load of <125 copies/mL). Children with infection due to pneumococcal serotype 19A were at highest risk of developing PPE (OR 7.44; 95% CI 1.10-50.4 vs all other typeable serotypes). The patients with CAP due to pneumococcal serotypes that are not included in the 13-valent conjugate vaccine (PCV13) were more frequently affected by PPE than those with infections associated with serotypes included in the vaccine, except for serotype 19A. Bacterial loads of ≥265 DNA copies/mL are significantly associated with PPE, and serotype 19A is significantly associated with a high bacterial load and the development of PPE. The mean bacterial load of the patients with empyema was higher than that of patients with simple PPE. Although further studies are required, it seems that serotypes not included in PCV13 can play a major role in causing a higher bacterial load and PPE.