March 27, 2014

Flu boosts pneumococcal colonization

Influenza and parainfluenza infections – but not other respiratory viruses – increase the risk of acquiring pneumococcal bacteria, the most common cause of severe pneumonia.

by Trisha Pasricha


Streptococcus pneumoniae (pneumococcus) – the most common bacterial cause of severe pneumonia – frequently colonizes the nasopharynx of children. Although most colonization does not result in disease, the acquisition of a new serotype (variety) of pneumococcus is critical in disease pathogenesis. Carlos G. Grijalva, M.D., MPH, assistant professor of Health Policy, and colleagues now report that a recent influenza or parainfluenza infection facilitates pneumococcal acquisition.

The investigators conducted a case-control study nested within the RESPIRA-PERU study of respiratory disease in young Peruvian children. They monitored acute respiratory diseases through weekly household visits, and obtained nasal swabs for virus detection when children were sick and monthly nasopharyngeal samples to assess pneumococcal colonization. The risk of acquiring a new pneumococcal serotype increased following influenza and parainfluenza infections, but not after infection with RSV, metapneumovirus, rhinovirus or adenovirus.

The findings, published in Clinical Infectious Diseases, suggest a selective synergism between certain respiratory viruses and pneumococcus. Since pneumococcal acquisition increases the risk of pneumococcal diseases, these observations can inform strategies for disease prevention.

This research was supported by the Thrasher Research Fund (grant 02832-9), the Vanderbilt University CTSA from the National Institutes of Health (grant RR024975) and investigator-initiated research grants from Pfizer (IIR WS1898786(0887X1-4492), IIR WS2079099).

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