biostudies-literatureDierckx LUniversiteit Antwerpen (UAntwerp)Universiteit Antwerpene0169624https://www.ebi.ac.uk/biostudies/studies/S-EPMC11980397biostudies-literatureUnknown63(4)<i>Streptococcus pneumoniae</i> serotype 23B, a non-vaccine serotype, has shown an increasing prevalence and penicillin non-susceptibility among carriage and invasive pneumococcal disease (IPD) isolates. Recently, a novel penicillin non-susceptible genotype has emerged, named 23B1. In the framework of the Belgian pneumococcal carriage study, we studied the prevalence of 23B₀/23B1 among 586 23B strains (2016-2022) in 172 day care centers from 6- to 30-month-old children and among 130 pediatric 23B IPD isolates (2007-2021). Pneumococci were whole genome sequenced to determine the capsular polysaccharide genotype and sequence type (ST). Antimicrobial susceptibility testing determined penicillin and amoxicillin MICs, as well as resistance to co-trimoxazole and levofloxacin. 23B carrJournal of clinical microbiologyPneumococcal genotype 23B1 as a driver of increased 23B serotype carriage, penicillin non-susceptibility, and invasive disease in Belgium: a retrospective analysis.PMC11980397VAX-Idea Methusalem fundsCuypers LBeutels PEkinci EMaertens KDierckx LWillen LRodriguez-Ruiz JPMalhotra-Kumar Svan Heirstraeten LTheeten HDesmet SfalsePneumococcal genotype 23B1 as a driver of increased 23B serotype carriage, penicillin non-susceptibility, and invasive disease in Belgium: a retrospective analysis.<i>Streptococcus pneumoniae</i> serotype 23B, a non-vaccine serotype, has shown an increasing prevalence and penicillin non-susceptibility among carriage and invasive pneumococcal disease (IPD) isolates. Recently, a novel penicillin non-susceptible genotype has emerged, named 23B1. In the framework of the Belgian pneumococcal carriage study, we studied the prevalence of 23B₀/23B1 among 586 23B strains (2016-2022) in 172 day care centers from 6- to 30-month-old children and among 130 pediatric 23B IPD isolates (2007-2021). Pneumococci were whole genome sequenced to determine the capsular polysaccharide genotype and sequence type (ST). Antimicrobial susceptibility testing determined penicillin and amoxicillin MICs, as well as resistance to co-trimoxazole and levofloxacin. 23B carr2025-01-01T00:00:00Z2025 Apr2025-07-05T03:04:30.402Z2025-07-05T03:04:30.402ZS-EPMC119803974007195410.1128/jcm.01696-24