Incidence of aerobactin-positive Escherichia coli strains in patients with symptomatic urinary tract infection.

A total of 323 Escherichia coli strains from children with primary acute non-obstructive pyelonephritis (n = 144) or cystitis (n = 56) and from adults with acute non-obstructive pyelonephritis (n = 66) or cystitis (n = 57) were examined for presence of the aerobactin-mediated iron uptake system and expression of P-fimbriae. Overall, pyelonephritogenic Escherichia coli strains were significantly more often aerobactin-positive (72%) than cystitis strains (42%) (p less than 0.001). Seventy-three percent of the isolates from children with acute pyelonephritis were aerobactin-positive compared to 54% of the cystitis strains (p less than 0.05). Pyelonephritogenic Escherichia coli strains from adults were also significantly more often aerobactin-positive (70%) than cystitis strains (30%) (p less than 0.001). The cystitis strains from children were more often aerobactin-positive than cystitis strains from adult patients (p less than 0.05). There was a significant correlation between presence of the aerobactin-mediated iron uptake system and expression of P-fimbriae in all strains (p less than 0.001).