<i>Escherichia coli</i>Harboring Shiga Toxin 2 Gene Variants: Frequency and Association with Clinical Symptoms

TLDR

The study genotyped Shiga toxin–producing Escherichia coli from patients with hemolytic‑uremic syndrome, diarrhea, or asymptomatic infection to assess associations between stx2 variants and clinical manifestations. The genotyping involved analyzing stx2 variants in 626 STEC isolates from these patient groups. Among 626 STEC isolates, stx2d and stx2e were absent in HUS cases but present in 15.6 % and 4.6 % of diarrhea isolates, respectively; stx2c frequency was similar across groups, none carried stx2f, and stx2d/e‑positive strains were eae‑negative, derived from older patients, and associated with milder disease and low HUS risk, whereas stx2c‑positive strains can cause HUS.

Abstract

Shiga toxin (Stx)–producing Escherichia coli (STEC) from patients with hemolytic-uremic syndrome (HUS), patients with diarrhea without HUS, or asymptomatic subjects were genotyped to assess associations between stx2 variants and clinical manifestations of infection. Neither stx2d nor stx2e was found in 268 STEC isolates from patients with HUS. Of 262 STEC isolates from patients with diarrhea, stx2d was found in 41 (15.6%; P<\,.000001), and stx2e was found in 12 (4.6%; P= .0004). The stx2c genotype frequency was similar among isolates from patients with HUS (3.7%) and diarrhea (5.0%). The frequencies of stx2c, stx2d and stx2e among 96 STEC isolates from asymptomatic subjects were comparable to those among isolates from patients with diarrhea. None of the 626 STEC isolates contained stx2f. All stx2d-positive or stx2e-positive STEC isolates were eae negative and originated from subjects older than those with STEC isolates with stx2c. stx2c-positive STEC isolates can cause HUS, but the presence of stx2d or stx2e may predict a milder disease with a minimal risk of HUS