A Review on Virulence Factors of Escherichia Coli

Most Escherichia coli (E. coli strains are normal commensals found in the intestinal tract of both humans and animals, while others are pathogenic to animals and humans. Pathogenic E. coli distinguished from normal flora by their possession of virulence factors. Hence, the main objective of this review is to appraise different virulence factors associated with occurrence of pathogenic E. coli infections. Some pathogenic strains cause diarrhoeal disease and are categorized into specific groups based on virulence properties, mechanisms of pathogenicity, clinical syndromes and distinct O: H serogroups. In this review, the most important virulence factors of E. coli including acid resistance, different adhesion proteins like fimbriae, fibrillae, curli and outer membrane protein A, the use of type III secretion systems by the bacteria to subvert eukaryotic signaling pathways by injecting virulence proteins into the host cell cytoplasm, the alkaline phosphatase encoded by PhoA gene in E. coli, the repeatsin toxin pore-forming toxins, oligopeptide toxin of E. coli, heat-labile enterotoxins, Vero/Shiga toxins and different pathogenicity islands which encode a variety of different virulence factors like adhesins, toxins, invasins, protein secretion systems, iron uptake systems and others were critically conferred. Thus, this review paper call for pioneering research on different virulence factors of E. coli in order to apply a well-coordinated control interventions.