For a study, it was determined that Enteroaggregative E. coli (EAEC) was linked to food-borne diarrhea outbreaks and stunted growth in children in underdeveloped nations. In 2011, a Shiga toxin-producing EAEC strain of serotype O104:H4 triggered one of Europe’s greatest food-borne illness outbreaks. Although the outbreak was linked to infected fenugreek sprouts, the causes for such prolonged contamination of sprouts were unknown. The researchers discovered that pathogenic Shiga toxin-producing EAEC O104:H4 227-11 and non-Shiga toxin-producing 042 strains both created high levels of exopolysaccharide structures (EPS) that were discharged to the external milieu under ambient temperature and in the minimum medium. Colanic acid (CA) was found as the exopolysaccharide. Surprisingly, the Shiga-toxin-producing EAEC strain 227-11 produced 3-6 times more CA than the 042 strain, implying that the CA was regulated differently in the two strains. The creation of extensive biofilm structures on the surface of sprouts was associated with the presence of CA. In EAEC 042, the wcaF-wza chromosomal region was necessary for CA synthesis. When the glycosyltransferase wcaE gene was deleted, the formation of CA in 042 was stopped, and the adhesion to sprouts was reduced when co-cultured at room temperature. Finally, the research implied that abundant CA production contributed to EAEC persistence in the environment, as well as a possible explanation for the 2011 Shiga toxin-producing EAEC outbreak.
Link:www.tandfonline.com/doi/full/10.1080/19490976.2018.1429877
