Nasopharyngeal pneumococcal carriage during childhood community-acquired alveolar pneumonia: Relationship between specific serotypes and coinfecting viruses

Background. Respiratory viruses and Streptococcus pneumoniae are known to be copathogens in childhood pneumonia. However, it is unclear whether all pneumococcal serotypes are equally prone to such interaction. We attempted to determine association between carried pneumococcal serotypes and respiratory viruses during childhood community-acquired alveolar pneumonia (CAAP). Methods. The study was conducted during respiratory syncytial virus (RSV) seasons, before pneumococcal vaccine introduction. Children aged <5 years diagnosed with CAAP with positive pneumococcal nasopharyngeal cultures from whom viral diagnostic tests were obtained were enrolled. Viral detection was done by culture, direct immunofluorescence assay (DFA) or polymerase chain reaction. Adjusted odd ratios (ORs) for serotype-specific carriage rates by presence of specific viruses were calculated: single RSV-positive (RSV[+]); other respiratory viruses (ORspVs[+]); and no respiratory virus (RspVs[-]). We compared invasive and noninvasive pneumococcal serotypes according to previous publications. Results. Invasive serotype colonization was significantly lower in RSV(+) versus RspVs(-) CAAP (OR = 0.18; 95% confidence interval[CI] = .05-.60), whereas colonization with noninvasive serotypes tended to be higher in RSV(+) (OR = 2.39; 95% CI = .98-5.79). Conclusions. We found an inverse relationship between pneumonia-associated invasive pneumococcal serotypes and RSV detection during CAAP. This finding may lead to better understanding of the interaction between respiratory viruses and S. pneumoniae in CAAP pathogenesis.