Abstract
BackgroundTo describe the temporal dynamics, molecular characterization, clinical and ex vivo virulence of emerging O1:K1 neonatal meningitis Escherichia coli (NMEC) strains of Sequence Type complex (STc) 95 in France.The national reference center collected NMEC strains and performed whole genome sequencing (WGS) of O1:K1 STc95 NMEC strains for phylogenetic and virulence genes content analysis. Data on the clinical and biological features of patients were also collected. Ex vivo virulence was assessed using the Dictyostelium discoideum amoeba model.ResultsAmong 250 NMEC strains collected between 1998 and 2015, 38 belonged to O1:K1 STc95. This clonal complex was the most frequently collected after 2004, representing up to 25% of NMEC strains in France. Phylogenetic analysis demonstrated that most (74%) belonged to a cluster designated D-1, characterized by the adhesin FimH30. There is no clinical data to suggest that this cluster is more pathogenic than its counterparts, although it is highly predominant and harbors a large repertoire of extraintestinal virulence factors, including a pS88-like plasmid. Ex vivo virulence model showed that this cluster was generally less virulent than STc95 reference strains of O45S88:H7 and O18:H7 serotypes. However, the model showed differences between several subclones, although they harbor the same known virulence determinants.ConclusionsThe emerging clonal group O1:K1 STc95 of NMEC strains is mainly composed of a cluster with many virulence factors but of only moderate virulence. Whether its emergence is due to its ability to colonize the gut thanks to FimH30 or pS88-like plasmid remains to be determined.
Highlights
To describe the temporal dynamics, molecular characterization, clinical and ex vivo virulence of emerging O1:K1 neonatal meningitis Escherichia coli (NMEC) strains of Sequence Type complex (STc) 95 in France
Epidemiology We characterized the temporal dynamics of the three major Sequence Type complex 95 (STc95)-serogroups that cause neonatal meningitis, O1, O18, and O45S88, by determining their respective rates between 1998 and 2015 (Fig. 1)
These three serogroups represented 30 to 50% of the E. coli meningitis strains among the 250 NMEC collected by the national reference center (NRC) during the study period
Summary
To describe the temporal dynamics, molecular characterization, clinical and ex vivo virulence of emerging O1:K1 neonatal meningitis Escherichia coli (NMEC) strains of Sequence Type complex (STc) 95 in France. Escherichia coli is a commensal of the gastrointestinal tract of vertebrates, including humans [1]. It is involved in intestinal and extraintestinal infections [2]. E. coli is the most frequent bacteria involved in preterm meningitis and the second most frequent in Sequence types (ST) are grouped into clonal complexes by their similarity to a central allelic profile (genotype). Plasmids similar to pS88 (pS88-like plasmid) have been detected in other clonal groups responsible for meningitis, such as O18:K1, O1:K1 and O83:K1 [8]
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