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

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). 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. 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 <24, ≥24-<36, ≥36-<60, and ≥60 months. PPE-associated Sts were St 1 (38%), St 5 (15%), St 19A (11%), St 7F (9%), St 3 (8%), and others (19%). St 1 was the most common 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. PCR is essential for determining the specific etiology of PPE.