Heterogeneity of phenotypic and genotypic traits including organic-acid resistance in Escherichia coli O157 isolates

We undertook an epidemiologic study for the sensitivity of both Shiga-like toxin (Slt)-producing Escherichia coli (STEC) O157 and non-STEC O157 strain s isolated from different patients with diarrhea to hydrochloric acid (HCl) and organic acids such as acetate, propionate, butyrate and lactate, and o ther pathogenic factors. The E. coli O157 isolates examined showed a wide v ariety of organic-acid susceptibility patterns. E. coli O157 isolates resis tant to HCl or acetate were found more frequently than those resistant to o ther organic acids. These isolates also showed diverse pathogenicity patter ns for the presence of the virulence genes, antibiotic susceptibility and p lasmid profile.