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

Abstract

Background: Changes in serotype distribution have been described after the switch from the 13-valent pneumococcal conjugate vaccine (PCV13) to the 10-valent pneumococcal conjugate vaccine (PCV10) in Belgium. Aim: To describe serotype's invasive disease potential and the detailed evolution of serotype distribution and antimicrobial susceptibility of pneumococcal isolates (carriage and IPD) in children up to 30 months of age over a period during and after the vaccine switch (2015)(2016)(2017)(2018). Methods: S. pneumoniae strains isolated from the nasopharynx of healthy children attending day-care centres (DCCs) and strains from normally sterile sites of children with IPD were serotyped (Quellungreaction) and antimicrobial susceptibility testing was performed. Invasive disease potential was defined as the serotype-specific odds ratio (OR). Results: The highly invasive (OR > 1) serotypes 12F, 1, 3, 24A/B/F, 33F, 19A, and 9N were not frequently carried (<7.5% of carriage strains). Different serotypes dominated in carriage (23B, 23A, 11A, 15B) versus IPD (12F, 19A, 10A, 33F). PCV13 vaccine serotypes increased in carriage (5.4% (25/463) in period 1 vs 10.3% (69/668) in period 3) and in IPD (7.3% (8/110 in period 1 vs 23.9% (34/142) in period 3) due to an increase (p < 0.01) in serotype 19A. The penicillin non-susceptibility of 19A was lower (p = 0.02) in carriage (6.8%) than in IPD (23.5%). Erythromycin and tetracycline non-susceptibility were more frequent (p < 0.01) in IPD (26.0%; 23.0%) compared to carriage strains (18.2%; 14.5%) and penicillin nonsusceptibility increased over the three year study period (carriage: 13.4%, 19.8%, 18.5%, p = 0.05; IPD: 11.8%, 15.0%, 20.4%, p = 0.02). Conclusion:Only some of the serotypes with high invasive disease potential (serotype 1, 3, 19A) in Belgium are included in PCV10 and/or PCV13. This reinforces the need for continuous monitoring, both in healthy children as in children with IPD, to better understand the dynamics of pneumococcal disease, to optimise the composition and implementation of PCVs.

Streptococcus pneumoniae Serotypes Carried by Young Children and Their Association With Acute Otitis Media During the Period 2016–2019

“…After the PCV13-to-PCV10 switch, the carriage proportion of PCV13-non-PCV10 vaccine serotype 19A showed an increasing trend in healthy children attending day care centers (DCC) (2). This increasing trend of serotype 19A was also observed in Belgian children with invasive pneumococcal disease (59). Consequently, PCV13 has been implemented again in 2019.…”

Nasopharyngeal Carriage in Children After the Introduction of Generalized Infant Pneumococcal Conjugate Vaccine Immunization in Germany

“…Similar trends were observed in Cyprus and France, where serotype 19A remained the most prominent VT serotype, and frequent NVTs were 6C, 11A, 15A, 15B/C, 23A, and 35B ( 13 , 26 ). In Belgium, direct effects on carriage of serotypes included or not included in different PCVs were immediately noticed after switching from one PCV formulation to the other ( 27 , 28 ). We observed a consistent decline of PCV13 serotypes until visit 4, suggesting that a PCV13 boosting after primary PCV7 or PCV10 series is able to reduce PCV13 serotype colonization.…”

Serotypes in Adult Pneumococcal Pneumonia in Spain in the Era of Conjugate Vaccines

“…For instance, serotype 11A is a frequent serotype causing acute exacerbations and pneumonia in patients with chronic obstructive pulmonary disease (COPD) [34,35]. In fact, serotype 11A is also frequent in carriage suggesting a low invasive disease potential [36,37]. An increase in serotype 11A isolates has been reported in Europe after the introduction of PCVs [33] due to the emergence of a new lineage related to the Spain 9V -156 clone (PMEN3).…”