Severe Escherichia coli infections in critical adult patients: two case reports and genomic analysis

Pathogenic Escherichia coli strains can infect a variety of body sites due to the expression of virulence factors necessary to overcome the host defenses. Here, we present two cases of E. coli infection in adults and discuss the associated genomic features. Whole-genome sequencing was performed using both Illumina iSeq 100 and Oxford Nanopore MinION systems. Assembly was carried out with Unicycler using a hybrid approach. The genomes were annotated with RASTtk and scanned for genes involved in antimicrobial resistance, virulence and stress response with AMRFinderPlus. Sequence analysis was conducted using tools from the Center for Genomic Epidemiology (CGE) website. The two strains, named SO80 and SO81, carried a genome of 5,229,956 and 5,437,935 base pairs, respectively. SO80 belonged to ST70 and carried 13 virulence factors, 6 of which were located on a 170 Kb plasmid, while SO81 belonged to ST69 and carried 29 virulence factors, 5 of which were located on a 113 Kb plasmid. Our work highlights key factors which may have contributed to the complicated clinical status of these patients, and provides new in-depth data on E. coli infections with few precedents in the literature.