Abstract
Etiology and serotyping of parapneumonic effusion (PPE) and the impact of vaccination was evaluated over a 12-year period, before and after the PCV13 introduction (2011) for Italian children From 0 to 16 years of age.Five hundred and two children were evaluated; 226 blood and 356 pleural fluid samples were obtained and tested using Realtime-PCR and culture. In the pre-PCV13 era S. pneumoniae was the most frequent pathogen identified (64/90; 71.1%) with a large predominance of serotypes 1 (42.4%), 3 (23.7%), 7F (5.1%) and 19A (11.9%).The impact of vaccination, calculated on children 0–8 years of age, demonstrated a significant reduction of PPE: with an incidence rate of 2.82 (95%CL 2.32–3.41) in the pre-PCV13 era and an age-standardized rate (ASR) of 0.66 (95% CL 0.37–1.99) in the post-PCV13 era, p < 0.0001. No increase in non-PCV13 serotypes was recorded. S. pneumoniae remained the most frequent pathogen identified in the post-PCV13 era in unvaccinated children with an unchanged serotype distribution: respectively 26/66 (39.4%), 25/66 (37.9%), 5/66 (7.6%), and 4/66 (6.1%) for 1, 3, 7F and 19A. On the other hand 7F and 19A disappeared in vaccinated children and serotype 1 and 3 decreased by 91.8% and 31.5%, respectively. Realtime PCR was significantly more sensitive than culture both in pleural fluid (79.7% vs 12.5%) and in blood (17.8% vs 7.4%).In conclusion, our findings indicate that routine immunization with PCV13 has significantly reduced the burden of childhood PPE in vaccinated children, without increasing PPE due to other bacteria and without serotype shift. Moreover, the impact of PCV13 may be underestimated due to the increase in pneumococcal surveillance in Italy. Data has also shown that Real-time PCR is an essential tool to better define the etiology of PPE and to monitor vaccination plans. Longer studies will be necessary to evaluate the role of herd protection in PPE prevention.
Highlights
The aims of our study were to describe the etiology of parapneumonic effusion (PPE) and pleural empyema (PE) in Italian children over a period of ten-years, to evaluate the impact of pneumococcal conjugate vaccination using a population-based molecular surveillance, and to determine the sensitivity of realtime polymerase chain reaction (RT-PCR) compared to the culture method in the diagnosis of PPE
As in the USA and Australia [3,4], S. pneumoniae is the most frequent pathogen involved in PPE (73%)
After S. pneumoniae, S. pyogenes was the most common pathogen and that is consistent with the results of a recent study in Canadian children [20]
Summary
Parapneumonic effusion (PPE) and pleural empyema (PE) are severe complications of community-acquired pneumonia (CAP) [1]. Over the last twenty years, a marked increase in the worldwide incidence of complicated pneumonia both in children and adults has been described [2,3]. The introduction of 7-valent pneumococcal conjugate vaccine (PCV7) into pediatric immunization programs has led to a dramatic reduction in overall and PCV7-type incidence of pneumonia and invasive pneumococcal disease (IPD). This benefit has been observed among unvaccinated age groups in countries where PCV-7 is routinely used, which suggests that PCV-7 provides herd protection [5,6]
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