Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2014

Respiratory syncytial virus and Streptococcus pneumoniae co-infections in severe paediatric respiratory infections (#90)

Jaelle Brealey 1 2 , Keith Chappell 1 2 , Ian Mackay 2 3 , Cheryl Bletchly 4 , Theo Sloots 3 , Peter Sly 5 , Paul Young 1 2
  1. School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD, Australia
  2. Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD, Australia
  3. Queensland Paediatric Infectious Diseases Laboratory, Sir Albert Sakzewski Virus Research Centre, University of Queensland, Brisbane, QLD, Australia
  4. Pathology Queensland Central, Royal Brisbane and Women’s Hospital, Brisbane, QLD, Australia
  5. Queensland Children’s Medical Research Institute, University of Queensland, Brisbane, QLD, Australia

Respiratory syncytial virus (RSV) is the most significant cause of severe respiratory infections in children, annually causing three million hospitalisations worldwide. RSV infections have a broad range of possible presentations, from asymptomatic to severe disease requiring hospitalisation. It is often not clear why severe disease manifests in some patients but not in others. Bacterial co-infections from opportunistic pathogens like Streptococcus pneumoniae have been associated with severe RSV infections and it has been suggested they may contribute to disease presentation. In nasopharyngeal samples from under 5 year olds with respiratory symptoms, we found high loads of bacteria in 75% of RSV infections, 25% of which were identified as S. pneumoniae. Microbial community profiling in a subset of RSV positive samples found a single bacterial species, such as S. pneumoniae, can constitute 80-95% of the nasopharyngeal community. To investigate the effect of this bacterial outgrowth on disease severity in RSV infection, we quantified the nasopharyngeal load of S. pneumoniae in under 2 year olds presenting with respiratory infection at the emergency department of the Royal Children’s Hospital, Brisbane. The severity of disease was evaluated upon enrolment to the study. S. pneumoniae has been detected in 60% of RSV infections to date, and these patients had increased disease severity compared to those with S. pneumoniae negative RSV infections. The overall load of nasopharyngeal bacteria was positively correlated with increased disease severity. Sample collection and screening is on-going, and the results to date suggest S. pneumoniae may be associated with severe paediatric RSV infection. We are now investigating the contribution of S. pneumoniae to disease severity in RSV infection in vitro, through profiling the host immune response in human bronchial epithelial cell culture. Understanding the relative roles of virus and bacteria in severe paediatric RSV infection will aid the development of improved treatment and prevention strategies.