Sustained high prevalence of pneumococcal serotype 1 in paediatric parapneumonic empyema in southern Spain from 2005 to 2009

The epidemiology and microbiological characteristics of paediatric parapneumonic empyema (PPE) before the introduction of the new generation of conjugate pneumococcal vaccines (10-valent and 13-valent) are described. All patients <14 years old admitted to a tertiary paediatric hospital with a diagnosis of PPE were prospectively enrolled from January 2005 to December 2009. Pneumococcal serotyping of culture-negative pleural fluid samples was performed using a multiplex real-time PCR assay. Overall, 219 patients had PPE. Incidence rates for PPE remained stable during the study period with a not significant increase in 2009 compared with 2005 (p 0.13), and were temporally associated with higher circulation of pandemic influenza A H1N1 during the last quarter in our population (p 0.001). Pneumococci were detected in 72% of culture-positive and 79% of culture-negative samples. Serotypes were determined in 104 PPE cases. Serotype 1 was the most prevalent serotype identified (42%) followed by serotypes 7F (20%), 3 (16%), 19A (8%) and 5 (7%). Serotype distribution remained similar during all time periods. Pneumococcal serotype 1 remained the most common cause of PPE during the 5-year study. The new generation of pneumococcal conjugate vaccines offers potential serotype coverage of 73% (10-valent) and 99% (13-valent) in the population studied suffering from PPE. Continuous epidemiological and molecular studies are paramount to monitor the impact of pneumococcal vaccines on the epidemiology of PPE.