Maximum likelihood phylogram displaying the relationship of the NMEC isolates with their associated serotype and virulence factor profile. Non-NMEC isolates used in the analysis for referencing are italicized. The phylogram was built and recombination regions removed employing Parsnp, using 185,911 core single nucleotide polymorphisms (SNPs) and NMEC strain IHE3034 as the reference. The scale bar indicates branch lengths in numbers of SNPs. NMEC isolates with available complete genomes are bold-italicized, while NMEC isolates that were completely sequenced in this study are indicated in bold and marked with an asterisk. The NMEC isolates that caused recrudescent invasive infection in this study are indicated in red. Branches are colored according to phylogroups: orange, phylogroup F; red, phylogroup C; green, phylogroup A; violet, phylogroup D and blue, phylogroup B2. The presence of specific virulence factors is indicated in dark blue. The phylogeny can be viewed interactively at http://microreact.org/project/oNfA4v16h3tQbqREoYtCXj-high-risk-escherichia-coli-clones-that-cause-neonatal-meningitis-and-association-with-recrudescent-infection.

Infection and treatment profile of patients suffering NM and recrudescent invasive infection. Indicated is the hospital admission history of patients, together with the timeline of sample collection, identified E. coli isolates and their infection source, and isolate identification based on whole genome sequencing, metagenomic sequencing (MetaWGS) or fimH amplicon sequencing. Genomic relatedness is indicated based on the number of single nucleotide polymorphisms (SNPs). The time of admission for the initial episode is indicated as Day 0, with subsequent timepoints indicated as days post initial admission. Admission and discharge days are indicated in red and green, respectively.

Relative abundance of bacterial genera (≥0.01%) in the gut microbiome of patient 2 at 8- and 12-week follow-up post relapsed infection (days 149 and 174 after initial admission) (A) and patient 3 during treatment and at discharge after the third episode (days 126 and 147 after initial admission) (B).

Summary of key NMEC virulence genes based on genome profiling performed in this study. Shown are shared virulence genes common to most NMEC, as well as ST95- and ST1193-specific NMEC virulence genes. Figure created with BioRender.com.

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Number of human-derived E. coli strains from ST95, ST1193, ST38, ST131, ST73, ST10 and ST69 available in the Enterobase database. Strains were stratified based on their year of isolation, spanning the periods before 2000, 2001-2005, 2006-2010, 2011-2015 and 2016-2022.

Antibiotic resistance gene profile of NMEC strains in the collection. The presence of each resistance gene is denoted by black shading.

ST95 NMEC strains contain more virulence factors than ST1193 NMEC strains. (A) The number of virulence genes (grouped as in Fig.1) for each strain within each ST. (B) The number of virulence genes grouped by their functions in ST95 versus ST1193 strains. P-value were calculated using Mann-Whitney two-tailed unpaired test.

K1 capsule production in NMEC. K1 capsule production was detected by ELISA using a monoclonal antibody specific for polysialic acid. Strains with an OD420 > 0.133 (mean + 3 standard deviations of a negative control kpsD mutant; dashed line) were considered positive for K1 capsule production. Data points represent independent biological replicates with horizontal lines as the mean.