Shiga-Toxin-Producing Strains of Escherichia coli O104:H4 and a Strain of O157:H7, Which Can Cause Human Hemolytic Uremic Syndrome, Differ in Biofilm Formation in the Presence of CO2 and in Their Ability to Grow in a Novel Cell Culture Medium.

ABSTRACT

One pathogen that commonly causes gastrointestinal illnesses from the consumption of contaminated food is Escherichia coli O157H7. In 2011 in Germany, however, there was a prominent outbreak of bloody diarrhea with a high incidence of hemolytic uremic syndrome (HUS) caused by an atypical, more virulent E. coli O104H4 strain. To facilitate the identification of this lesser-known, atypical E. coli O104H4 strain, we wanted to identify phenotypic differences between it and a strain of O157H7 in different media and culture conditions. We found that E. coli O104H4 strains produced considerably more biofilm than the strain of O157H7 at 37 °C (p = 0.0470-0.0182) Biofilm production was significantly enhanced by the presence of 5% CO2 (p = 0.0348-0.0320). In our study on the innate immune response to the E. coli strains, we used HEK293 cells that express Toll-like receptors (TLRs) 2 or 4. We found that E. coli O104H4 strains had the ability to grow in a novel HEK293 cell culture medium, while the E. coli O157H7 strain could not. Thus, we uncovered previously unknown phenotypic properties of E. coli O104H4 to further differentiate this pathogen from E. coli O157H7.