Background: In the last decade, the importance of hetero-pathogenic enteroaggregative Shiga-toxin-producing E. coli for public health has increased. Recently, we described the genetic background of the EAHEC O181:H4 strain of ST678 carrying the stx2 gene in prophage and five plasmids, including the plasmid-carrying aggR and aaiC genes. Here, we present the morphological and enzymatic characteristics of this strain, as well as susceptibility to antimicrobials, biofilm formation, etc. Methods: Bacterial morphology was studied using an electron microscope. Susceptibility to antimicrobials was determined using the microdilution method. Cytotoxicity was estimated in Vero cells. Virulence was studied on mice.
Results: The morphological and enzymatic properties of the hetero-pathogenic EAHEC strain were typical for E. coli; electron microscopy revealed the specific flagella. The strain was susceptible to most antibiotics and disinfectants but resistant to ampicillin and ciprofloxacin and showed a high degree of biofilm formation. Cytotoxicity towards Vero cells was estimated as 80%.
Conclusions: The emergence of a new O181:H4 EAHEC strain poses a potential threat to humans because of the virulence potential that must be taken into account in the epidemiological analysis of outbreaks and sporadic cases of foodborne infections associated with hemolytic-uremic syndrome.
Keywords: EAHEC; antimicrobials; biofilm; disinfectants; hemolytic–uremic syndrome.