Escherichia coli strains causing urinary tract infection in uncircumcised infants resemble urosepsis-like adult strains

Purpose: Urinary tract infection (UTI) is the most frequent bacterial infection in infants younger than 90 days, and mainly affects uncircumcised males. In an attempt to unravel further the pathophysiology of UTI in this age group we used molecular methods to characterize Escherichia coli strains responsible for community acquired UTI in male and female infants and in adults. Materials and Methods: A total of 79 E. coli isolates from uncircumcised male and female infants with UTI and no urinary tract abnormalities and 41 E. coli pyelonephritis isolates from nonhost compromised adults with bacteremia were characterized in terms of phylogenic relatedness and virulence factors. Results: Males were infected by strains with a genetic background and virulence factors different from those affecting females but similar to those of adult pyelonephritis strains. Conclusions: Our molecular approach indicates that uncircumcised male infants are at higher risk for infection with highly virulent uropathogenic E. coli strains than are females. Preputial colonization may have a key role in the selection of such strains.