Abstract
BackgroundRespiratory syncytial virus (RSV) is an important cause of lower respiratory tract infections in infants. A small percentage of the infected infants develops a severe infection, while most of these severely ill patients were previously healthy. It remains unclear why these children develop severe RSV infections. In this study, we investigate whether pneumococcal nasopharyngeal carriage patterns correlate with mucosal inflammation and severity of disease.MethodsIn total, 105 infants hospitalized with RSV infection were included and recovery samples were taken from 42 patients. The presence and density of Streptococcus pneumoniae was determined by RT qPCR to study its relation to viral load, inflammation (MMP-9 and IL-6) and severity of RSV disease.ResultsWe show that pneumococcal presence or absence in the nasopharynx does not correlate with viral load, inflammation or severity of disease. However, when pneumococcus is present in patients, a higher nasopharyngeal pneumococcal density was correlated with a higher RSV load, higher MMP-9 levels and a less severe course of disease.ConclusionsOur results show correlations between S. pneumoniae density and viral load, inflammation and disease severity, suggesting that pneumococcal density may be an indicator for severity in paediatric RSV disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1454-x) contains supplementary material, which is available to authorized users.
Highlights
Respiratory syncytial virus (RSV) is an important cause of lower respiratory tract infections in infants
Presence of S. pneumoniae does not correlate with viral load, inflammation or disease severity In all collected samples, 16 s rRNA could be detected by RT qPCR
There were no significant differences between the pneumococcal positive group compared to the pneumococcal negative group, regarding viral load (Fig. 1a)
Summary
Respiratory syncytial virus (RSV) is an important cause of lower respiratory tract infections in infants. A small percentage of the infected infants develops a severe infection, while most of these severely ill patients were previously healthy. It remains unclear why these children develop severe RSV infections. Respiratory syncytial virus (RSV) is a major cause of severe respiratory infections in infants below 6 months of age and the most common cause for bronchiolitis. 60 % of all infants are infected with RSV during their first winter season and at the age of 2 almost all children have encountered RSV [1]. A considerable part of the severely ill patients were previously
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