Laboratory-based, 2-year surveillance of pediatric parapneumonic pneumococcal empyema following heptavalent pneumococcal conjugate vaccine universal vaccination in Madrid.

Background: In October 2006, the heptavalent pneumococcal conjugate vaccine was included in the Madrid vaccination calendar, warranting serotype (St) surveillances in pneumococcal pediatric parapneumonic empyema (PPE). Methods: A prospective 2-year (May 2007-April 2009) laboratory-confirmed PPE surveillance was performed in 22 hospitals. All isolates (for serotyping) and culture-negative pleural fluids were sent to the reference laboratory for polymerase chain reaction (PCR) analysis. Results: We identified 138 PPEs. Pneumococcal etiology was confirmed in 100 cases: 38 by culture, 62 by PCR. Mean age was 44.64 ± 26.64 months; 51.0% were male. Similar pneumococcal PPE distribution was found by age: 21% to 28% in 36 months, with similar rates to St 19A in <24 months (≈30%). In ≥24 -≤36 months, St 3 (21.7%), St 1 and St 5 (17.4% each) were the most frequent. No differences in demographic data, vaccination status, length of hospitalization, and outcome were found between culture-negative (PCR positive) and culture-positive PPE patients, with significantly higher percentages of St 1 and St 5 in culture-positive PPEs. Total rates of St 1 (38%), St 5 (15%), and St 7F (9%) would have been over-represented considering only positive-culture PPEs (n = 38), by increasing to 52.6% (St 1), 23.7% (St 5), and 10.5% (St 7F). The 13-valent pneumococcal conjugate vaccine would cover 84.0% of Sts causing PPEs. Conclusions: PCR is essential for determining the specific etiology of PPE.