Virulence Factor Genes in Invasive Escherichia coli Are Associated with Clinical Outcomes and Disease Severity in Patients with Sepsis: A Prospective Observational Cohort Study

BACKGROUND: Escherichia coli harbours virulence factors that facilitate the development of bloodstream infections. Studies determining virulence factors in clinical isolates often have limited access to clinical data and lack associations with patient outcome. The goal of this study was to correlate sepsis outcome and virulence factors of clinical E. coli isolates in a large cohort.

METHODS: Patients presenting at the emergency department whose blood cultures were positive for E. coli were prospectively included. Clinical and laboratory parameters were collected at admission. SOFA-score was calculated to determine disease severity. Patient outcomes were in-hospital mortality and ICU admission. Whole genome sequencing was performed for E. coli isolates and virulence genes were detected using the VirulenceFinder database.

RESULTS: In total, 103 E. coli blood isolates were sequenced. Isolates had six to 41 virulence genes present. One virulence gene, kpsMII_K23, a K1 capsule group 2 of E. coli type K23, was significantly more present in isolates of patients who died. kpsMII_K23 and cvaC (Microcin C) were significantly more frequent in isolates of patients who were admitted to the ICU. Fourteen virulence genes (mchB, mchC, papA_fsiA_F16, sat, senB, iucC, iutA, iha, sfaD, cnf1, focG, vat, cldB, and mcmA) significantly differed between patients with and without sepsis.

CONCLUSIONS: Microcins, toxins, and fimbriae were associated with disease severity. Adhesins and iron uptake proteins seemed to be protective. Two genes were associated with worse clinical outcome. These findings contribute to a better understanding of host-pathogen interactions and could help identifying patients most at risk for a worse outcome.