The aetiology of community-acquired pneumonia and implications for patient management.

PURPOSE: Understanding which pathogens are associated with clinical manifestation of community-acquired pneumonia (CAP) is important to optimise treatment. We performed a study on the aetiology of CAP and assessed possible implications for patient management in the Netherlands. METHODS: Patients with CAP attending the emergency department of a general hospital were invited to participate in the study. We used an extensive combination of microbiological techniques to determine recent infection with respiratory pathogens. Furthermore, we collected data on clinical parameters and potential risk factors. RESULTS: From November 2007 through January 2010, 339 patients were included. Single bacterial infection was found in 39% of these patients, single viral infection in 12%, and mixed bacterial-viral infection in 11%. Streptococcus pneumoniae was the most frequently identified pathogen (22%; n=74). Infection with atypical bacteria was detected in 69 (20%) of the patients. CONCLUSION: Initial empirical antibiotics should be effective against S. pneumoniae, the most common pathogen identified in CAP patients. The large proportion of patients with infection with atypical bacteria points to the need for improved diagnostic algorithms including atypical bacteria, especially since these atypical bacteria are not covered by the first-choice antibiotic treatment according to the recently revised Dutch guidelines on the management of CAP.

Seroprevalence of IgG antibodies against 13 vaccine Streptococcus pneumoniae serotypes in the Netherlands.

In this study the seroprevalence of IgG antibodies against 13 vaccine serotypes of the pneumococcus was assessed in the Netherlands. Sera from 7904 persons obtained in a cross-sectional population-based study were analysed. The 13 serotype specific IgG concentrations were assessed simultaneously using a fluorescent bead-based multiplex immuno assay (MIA). Overall, the geometric mean IgG concentrations (GMCs) against the 13 serotypes in unvaccinated individuals increased with age up to 5 years and remained at a plateau thereafter. The data also show that individuals develop antibodies against an increasing number of different serotypes with increasing age. The highest GMCs were found for antibodies directed against serotype 14 and 19F, whereas antibodies against serotypes 4 and 5 had the lowest GMCs. There was no uniform relationship between the occurrence of serotypes causing invasive pneumococcal disease (IPD) and the GMCs against these serotypes. Increased IPD incidence in the elderly did not seem to be the result of a decline in the concentration of IgG antibodies.