Uropathogenic Escherichia coli in urinary tract infections

The human urinary tract is one of the most common sites of bacterial infection. Uncomplicated urinary tract infections (UTIs) account for >10 million medical visits annually and almost US$4 billion in medical expenditures each year in the United States. In addition to structural and urodynamic abnormalities (either anatomical- or healthcare-associated), pregnancy, diabetes, bladder catheterization, prostate enlargement, HIV infection, and sexual activity have been described as predisposing factors for the development of UTIs. However, most outpatients with UTI are otherwise healthy women with no identifiable risk factors. By the fourth decade of life, half of all women report having had at least one UTI. Of those, 25% will experience a second UTI, and 3% will experience a third recurrence within 6 months after treatment of the initial infection. Molecular typing studies suggest that up to two-thirds of recurrent infections arise from the same bacterial strain as that causing the initial infection. Same-strain recurrent infections have been observed up to 3 years after an initial UTI. As these chronic and recurrent UTIs cause a substantial deterioration in patients’ quality of life, a more thorough understanding of the processes underlying the initiation and recurrence of these infections is needed.