Assessment of the Nasopharyngeal Carriage of Streptococcus Pneumoniae (Sp) and Other Common Pathogens in Infants (6-30 Months of Age) With Acute Otitis Media and in Healthy Infants (6-30 Months of Age) Attending Day-care Centers

Rationale

In Belgium, a unique situation exists for two reasons: on the one hand, the pneumococcal conjugate vaccine (PCV) program, which started in 2007, has quickly reached high coverage in infants: 3-dose coverage rose from 89 % in 2008 to 96.5 % in 2012 in Flanders and from 80.7 % in 2009 to 89.2 % in 2012 in Wallonia; and on the other hand, serotype coverage has moved from PCV7 (since 2007) to PCV13 (since 2011) and very recently to PCV10 (since July 2015 in Flanders and expected in May 2016 in the French Community). Invasive pneumococcal disease (IPD) surveillance has demonstrated a major impact on PCV13 serotypes in infants < 2 years of age. The impact of the current change in PCV-program is hard to predict, but could eventually result in a re-emergence of serotypes not covered by PCV10 (i.e. 3, 6A and 19A).

With this unique situation the foundation was laid for a carriage study during which the nasopharyngeal carriage of Streptococcus pneumonia (Sp) and other common colonizers of the nasopharynx will be studied in infants with acute otitis media (AOM) and in healthy infants attending day-care centers (DCC), two populations with high reported pneumococcal carriage. Young children are an important reservoir and major source of transmission of bacteria to the whole community and thus the preferred population to study nasopharyngeal (NP) carriage.

Aim of the study

The main aim of this study is to evaluate if changes in the conjugate anti-pneumococcal vaccination program in Belgium have an impact on the nasopharyngeal carriage of Pneumococcus in infants aged 6-30 months suffering from AOM or attending day-care, in order to guide future pneumococcal vaccine program decisions and vaccine development, and to feed AOM treatment guidelines in a PCV-program environment. The study will monitor overall pneumococcal carriage, the serotypes involved and the sensitivity of the isolated strains to antibiotics. In addition, the rhinopharyngeal carriage of other common nasopharyngeal colonizers associated with disease, in particular Haemophilus influenzae, will be studied in order to evaluate if changes in pneumococcal carriage impact on the carriage of those pathogens. In infants with AOM, the study will also monitor the clinical course of the AOM and a second nasopharyngeal sample will be taken in case of antibiotic treatment failure or AOM recurrence to identify any association with the carried pathogen.