Escherichia coli ST131 isolates are rare in human meningitis but belong to a distinct O25b-fimH22 clade B lineage shared with avian pathogenic Escherichia coli

Abstract

Escherichia coli ST131 is a globally disseminated extraintestinal lineage best known for its resistance-driven expansion, yet it is rarely reported as a cause of neonatal meningitis. Whether specific ST131 sublineages retain neuroinvasive potential remains poorly understood. We analysed a 25-year nationwide French collection of 355 neonatal meningitis E. coli isolates recovered between 2000 and 2024. ST131 isolates were characterized by whole-genome sequencing, and ST131-O25b- fim H22 genomes were contextualized in a phylogeny including human-associated genomes and selected animal- and food-associated references. An extended dataset of 623 animal- and food-associated ST131-O25b- fim H22 genomes was analysed separately to assess the distribution of virulence-associated lineages across non-human reservoirs. Nine neonatal meningitis isolates belonged to ST131. Six were O25b:H4- fim H22 clade B isolates carrying K1, invasion of brain endothelium A ( ibe A) and pS88-like markers; non- fim H22 isolates had heterogeneous virulence/resistance profiles, including two with sen B -cjr ABC-positive pRS218-like signatures. Phylogenomic analysis placed French ST131-O25b- fim H22 meningitis isolates within a conserved 85-genome lineage spanning 1995–2024 and comprising meningitis, bloodstream, urinary and avian-source isolates. This lineage was enriched in K1, ibe A, pS88-like signatures and virotype D/D4, with most isolates sharing HC100 assignment (≤100 core-genome allelic differences). The extended animal- and food-associated dataset identified a large poultry-associated HC100 population with the same K1/ ibe A/pS88-like profile, whereas pRS218-like signatures were uncommon and mainly canine or feline. Although ST131 rarely causes neonatal meningitis, the isolates identified belong to a conserved ancestral ST131-O25b- fim H22 clade B lineage combining the major determinants of neonatal meningitis E. coli pathogenicity and are closely related to poultry-associated populations. Together with previous observations in ST95, these findings support a shared avian reservoir for highly pathogenic extraintestinal pathogenic E. coli lineages, distinct from the resistance-driven expansion of ST131-H30 and highlight the importance of One Health genomic surveillance.