Virulence Profiling and Quantification of Verocytotoxin-ProducingEscherichia coliO145:H28 and O26:H11 Isolated During an Ice Cream–Related Hemolytic Uremic Syndrome Outbreak

Abstract

In September-October 2007, a mixed-serotype outbreak of verocytotoxin-producing Escherichia coli (VTEC) O145:H28 and O26:H11 occurred in the province of Antwerp, Belgium. Five girls aged between 2 and 11 years developed hemolytic uremic syndrome, and seven other coexposed persons with bloody diarrhea were identified. Laboratory confirmation of O145:H28 infection was obtained for three hemolytic uremic syndrome patients, one of whom was coinfected with O26:H11. The epidemiological and laboratory investigations revealed ice cream as the most likely source of the outbreak. The ice cream was produced at a local dairy farm using pasteurized milk. VTEC of both serotypes with indistinguishable pulsed-field gel electrophoresis patterns were isolated from patients, ice cream, and environmental samples. Quantitative analysis of the ice cream indicated concentrations of 2.4 and 0.03 CFU=g for VTEC O145 and O26, respectively. Virulence typing revealed that the repertoire of virulence genes carried by the O145:H28 outbreak strain was comparable to that of O157 VTEC and more exhaustive as compared to the O26:H11 outbreak strain and nonrelated clinical strains belonging to these serotypes. Taken together, these data suggest that O145:H28 played the most important role in this outbreak.

Incidence and Virulence Determinants of Verocytotoxin-Producing Escherichia coli Infections in the Brussels-Capital Region, Belgium, in 2008–2010

“…Although O26 strains have been associated with HUS in Belgium previously (10), none were associated with HUS in this study. Most were associated with nonbloody diarrhea and abdominal pain, but two patients with O26 infection presented macroscopic blood in their stools.…”

Simultaneous Presence of Insertion Sequence Excision Enhancer and Insertion Sequence IS 629 Correlates with Increased Diversity and Virulence in Shiga Toxin-Producing Escherichia coli

“…1) even when all four O145:H28 strains are closely related; however, these strains differed by food matrix: RM13516 was isolated in Belgium in 2007 from an icecream outbreak (39,40), whereby RM12581 was a lettuce-associated outbreak strain identified in the United States in 2010 (41). Little is known about serotype O145:H28 genetic diversity, but this finding suggests that it might have two different lineages that acquired IEE separately.…”

“…Further activation of transposition/excision mechanisms produced a perfect excision of the IS629, resulting in a strain with a functional stx 2 gene (45). Many other non-O157 serotypes appear to be emerging to highly pathogenic serotypes and are being isolated from unusual sources (39)(40)(41). Genomic plasticity allows rapid adaptation to changing environments, which provides an evolutionary advantage to virulent E. coli serotypes.…”

Complete Genome Sequences of Two Escherichia coli O145:H28 Outbreak Strains of Food Origin

“…E. coli O145:H28 strain RM12581 was isolated from bagged romaine lettuce during a multistate outbreak of O145 infections associated with romaine lettuce consumption in April and May 2010 in the United States (9). Strain RM12761 was isolated from ice cream during an outbreak of O145 and O26 infections among ice cream consumers in Belgium in 2007 (7, 10). We reported previously the complete genome sequence of a clinical isolate linked to each of the two outbreaks (11).…”