Group B streptococcal disease in infants 0-3 months in The Netherlands, 1987-2023: a nationwide genomic and epidemiological surveillance study.

BACKGROUND

Group B Streptococcus (GBS) is the leading cause of sepsis and meningitis in infants. The molecular epidemiology and potential vaccine coverage of GBS disease in infants was assessed in the Netherlands over a 37-year period.

METHODS

This nationwide observational study identified infants aged 0-89 days with GBS culture-positive sepsis or meningitis between July 1987 and June 2024, through Dutch surveillance. Serotype was determined by latex agglutination. Whole-genome sequencing determined the clonal complex (CC) using multi-locus sequence typing (MLST) and identified virulence factors associated with meningitis. Strain coverage by the maternal vaccines GBS6 and GBS-AlpN were analysed.

FINDINGS: 2212 episodes were identified; 1307 (59%) early onset disease (0-6 days) and 905 (41%) late onset disease (7-89 days). Mean annual incidence was 0·33 per 1000 live births and significantly increased from 0·19 in 1987 to 0·57 in 2023 due to an increase in sepsis cases (p < 0·0001). Serotype data was available for 2163 (98%) of 2212 isolates, of which serotype III was most common (1316/2163; 61%), followed by Ia (383/2163; 18%) and II (123/2163; 6%). MLST data was available for 1723 (78%) isolates; CC17 was most common (705/1723; 41%). CC17 increased from 29% (90/308) in 1987-1996 to 49% (262/538) in 2014-2023 (p < 0·0001). 97% (2095/2163) of cases would be covered by the GBS6 vaccine, and 99% (1709/1723) by GBS-AlpN.

INTERPRETATION: GBS disease is still increasing in the Netherlands. The GBS6 and GBS-AlpN vaccines would potentially prevent >96% of cases.

FUNDING: Netherlands Organisation for Health Research and Development (ZonMW) and ItsME foundation.