Research Article
Chappell KJ, Brealey JC, Ma
Abstract
Background: Respiratory syncytial virus (RSV) is the leading cause of severe respiratory tract infection requiring hospitalization among infants and young children. Furthermore, RSV infection has been shown to stimulate increased bacterial load in the nasopharynx and to promote bacterial otitis media and/or pneumonia. Objective: To assess the diversity and prevalence of bacterial pathogens associated with viral infections of the respiratory tract among young children. Study design: During the 2012 seasonal RSV epidemic in South East Queensland, Australia, 201 nasopharyngeal aspirates (NPAs) collected from symptomatic children under five years of age and sent for pathology laboratory screening were examined. Samples were analysed for common viral and bacterial pathogens by quantitative PCR and culturing techniques. For a subset of 29 samples the complete microbial community was profiled using cultureindependent PCR and pyrosequencing of the 16S ribosomal RNA gene. Results: RSV infection was confirmed in 67 patients, of which 49 were positive for high bacterial load in the upper respiratory tract. Bacterial detection was significantly higher amongst RSV positive samples (73.1%) than amongst RSV negative samples (56.7%) (p=0.03) and was independent of other viral pathogens. The predominant bacterial species detected during RSV infections were Moraxella catarrhalis (22), Streptococcus pneumoniae (17), Haemophilus influenzae (5) and Staphylococcus aureus (6). Notably, microbial profiling analysis showed that during either RSV or rhinovirus infections a single bacterial species can constitute between 80 and 95% of the bacterial community present. Conclusions: In nasopharyngeal samples collected from symptomatic children, high levels of bacteria were found more commonly in the presence of RSV infections. Most significantly, RSV infection was associated with a 3-fold increase in S. pneumoniae detection.