In-depth analysis of pneumococcal serotypes in Belgian children (2015–2018): Diversity, invasive disease potential, and antimicrobial susceptibility in carriage and disease

Changes in serotype distribution have been described after the switch from 13-valent pneumococcal conjugate vaccine (PCV13) to 10-valent (PCV10) Belgium. To describe serotype’s invasive disease potential and detailed evolution of antimicrobial susceptibility isolates (carriage IPD) children up 30 months age over a period during (2015–2018). S. pneumoniae strains isolated nasopharynx healthy attending day-care centres (DCCs) normally sterile sites with IPD were serotyped (Quellung-reaction) testing was performed. Invasive defined as serotype-specific odds ratio (OR). The highly (OR > 1) serotypes 12F, 1, 3, 24A/B/F, 33F, 19A, 9N not frequently carried (<7.5% carriage strains). Different dominated (23B, 23A, 11A, 15B) versus (12F, 10A, 33F). PCV13 increased (5.4% (25/463) 1 vs 10.3% (69/668) 3) (7.3% (8/110 23.9% (34/142) due an increase (p < 0.01) 19A. penicillin non-susceptibility 19A lower = 0.02) (6.8%) than (23.5%). Erythromycin tetracycline more frequent (26.0%; 23.0%) compared (18.2%; 14.5%) three year study (carriage: 13.4%, 19.8%, 18.5%, p 0.05; IPD: 11.8%, 15.0%, 20.4%, 0.02). Only some high (serotype 19A) Belgium are included PCV10 and/or PCV13. This reinforces need for continuous monitoring, both IPD, better understand dynamics disease, optimise composition implementation PCVs.