Virulence Factors of E. Coli, Associated With Urinary Tract Infections

Urinary tract infections (UTIs) are the most common type of infections second only to respiratory tract infections. Millions of UTI cases are reported each year, affecting in- and outpatients. The most frequent causative agents of UTIs are the enteric Gram-negative bacteria, among which Escherichia coli (E. coli) dominates. While most strains of E. coli are harmless and indeed play a beneficial role in gut health, some strains (uropathogenic Escherichia coli, UPEC) can cause infections when they are translocated to generally sterile body areas, such as the urinary tract. This review presents the wide range of virulence factors of UPEC, involved in the urinary tract colonization, infection development and host tissue invasion. Cell-associated and extracellular key virulence factors such as adhesins, invasins, iron acquisition factors, factors mediating serum resistance, toxins and structural components are discussed in detail. Also, the review focuses on the process of biofilm formation, another crucial virulence factor in UPEC, responsible for UTI persistence, reoccurrence and antimicrobial therapy failure. The regulatory mechanisms involved in biofilm production are also discussed.