Genetic Characterization of Intimin Gene ( eae ) in Clinical Shiga Toxin-Producing Escherichia coli Strains from Pediatric Patients in Finland

Shiga toxin (Stx)-producing (STEC) infections cause outbreaks of severe disease in children ranging from bloody diarrhea to hemolytic uremic syndrome (HUS). The adherent factor intimin, encoded by , can facilitate the colonization process of strains and is frequently associated with severe disease. The purpose of this study was to examine and analyze the prevalence and polymorphisms of in clinical STEC strains from pediatric patients under 17 years old with and without HUS, and to assess the pathogenic risk of different subtypes. We studied 240 STEC strains isolated from pediatric patients in Finland with whole genome sequencing. The gene was present in 209 (87.1%) strains, among which 49 (23.4%) were from patients with HUS, and 160 (76.6%) were from patients without HUS. O157:H7 (126, 60.3%) was the most predominant serotype among -positive STEC strains. Twenty-three different genotypes were identified, which were categorized into five subtypes, i.e., γ1, β3, ε1, θ and ζ3. The subtype -γ1 was significantly overrepresented in strains from patients aged 5-17 years, while β3 and ε1 were more commonly found in strains from patients under 5 years. All O157:H7 strains carried -γ1; among non-O157 strains, strains of each serotype harbored one subtype. No association was observed between the presence of /its subtypes and HUS. However, the combination of -γ1+ was significantly associated with HUS. In conclusion, this study demonstrated a high occurrence and genetic variety of in clinical STEC from pediatric patients under 17 years old in Finland, and that is not essential for STEC-associated HUS. However, the combination of certain subtypes with subtypes, i.e., -γ1+ , may be used as risk predictors for the development of severe disease in children.