Non‐O157 Shiga Toxin–Producing<i>Escherichia coli</i>Infections in the United States, 1983–2002

TLDR

Shiga toxin–producing Escherichia coli O157:H7 is a well‑known cause of bloody diarrhea and hemolytic‑uremic syndrome, while non‑O157 STEC, which were underrecognized due to diagnostic limitations, accounted for 940 isolates from 1983‑2002 with common serogroups O26, O111, O103, O121, O45, and O145. The study aims to improve surveillance to better define the incidence and pathological spectrum of emerging non‑O157 STEC agents. This requires heightened clinical suspicion, enhanced laboratory isolation, and ongoing serotyping of isolates in public health laboratories. Non‑O157 STEC infections peak in summer, mainly affect children (median age 12), and are linked to virulence genes stx2 and eae—stx2 strongly associated with HUS and eae with bloody diarrhea; serogroup O111 accounts for most HUS cases and several outbreaks, and overall non‑O157 STEC can cause severe illness comparable to O157, with stx2‑producing strains more likely to cause HUS than stx1‑producing strains.

Abstract

Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a well-recognized cause of bloody diarrhea and hemolytic-uremic syndrome (HUS). Non-O157 STEC contribute to this burden of illness but have been underrecognized as a result of diagnostic limitations and inadequate surveillance.Between 1983 and 2002, 43 state public health laboratories submitted 940 human non-O157 STEC isolates from persons with sporadic illnesses to the Centers for Diseases Control and Prevention reference laboratory for confirmation and serotyping.The most common serogroups were O26 (22%), O111 (16%), O103 (12%), O121 (8%), O45 (7%), and O145 (5%). Non-O157 STEC infections were most frequent during the summer and among young persons (median age, 12 years; interquartile range, 3-37 years). Virulence gene profiles were as follows: 61% stx(1) but not stx(2); 22% stx(2) but not stx(1); 17% both stx(1) and stx(2); 84% intimin (eae); and 86% enterohemolysin (E-hly). stx(2) was strongly associated with an increased risk of HUS, and eae was strongly associated with an increased risk of bloody diarrhea. STEC O111 accounted for most cases of HUS and was also the cause of 3 of 7 non-O157 STEC outbreaks reported in the United States.Non-O157 STEC can cause severe illness that is comparable to the illness caused by STEC O157. Strains that produce Shiga toxin 2 are much more likely to cause HUS than are those that produce Shiga toxin 1 alone. Improving surveillance will more fully elucidate the incidence and pathological spectrum of these emerging agents. These efforts require increased clinical suspicion, improved clinical laboratory isolation, and continued serotyping of isolates in public health laboratories.