Pneumococcal density and respiratory co-detection in severe pediatric pneumonia in Laos

There is growing evidence on the importance of bacterial/viral interaction in the course of pneumonia. In Laos, no study has investigated respiratory pathogen co-detection. We conducted a study at Mahosot Hospital in Vientiane to determine whether bacterial/viral co-detection and pneumococcal density are associated with severe pneumonia. Between December 2013 and December 2016, 934 under 5 years old hospitalized children with ARI were enrolled. Swabs from the upper respiratory tract were collected and analyzed by real-time PCR. The most common co-detected microorganisms were Streptococcus pneumoniae/Haemophilus influenzae (24%), Respiratory Syncytial Virus (RSV)/S. pneumoniae (12%) and RSV/H. influenzae (16%). Pneumococcal density was 4.52 times higher in influenza virus positive participants. RSV/S. pneumoniae and RSV/H. influenzae co-detections were positively associated with severe pneumonia in univariate analysis (OR 1.86, 95%CI:1.22-2.81, p = 0.003 and OR 2.09, 95%CI:1.46-3.00), but not confirmed in adjusted analysis (aOR 0.72, 95%CI:0.38-1.6, p = 0.309 and aOR 1.37, 95%CI:0.73-2.58). In RSV positive patients, there was no association between pneumococcal density and severe pneumonia. Our findings confirmed an association between pneumococcal density and influenza but not RSV severe pneumonia in young children. Results highlight the complexity of the interaction of viral/bacterial pathogens, which might not have a simple synergistic action in the evolution of pneumonia.