Host-parasite relationships in acute pyelonephritis.

During a 1-year prospective study, a total of 15 patients (seven children and eight adults) were observed with acute nonobstructive pyelonephritis. P-fimbriated Escherichia coli was the causative pathogen in all 15 patients. The same serotype of E coli that was P-fimbriated was isolated from the vaginal introitus of 60% and from the fecal flora of 86% of these patients. The only host abnormality was moderate vesicoureteral reflux in 20% of the patients. Uroepithelial cells were isolated from the first morning-voided urine from patients, who had recovered from pyelonephritis, and from age-matched controls. Using fluorescein-labelled type 1 and P-fimbriated reference strains of E coli and fluorescence-activated cell sorting (FACS) analysis, we evaluated their ability to adhere to these uroepithelial cells. P-fimbriated E coli was more adherent than type 1 fimbriated E coli, and more P-fimbriated E coli adhered to the patients' cells. Our data show that both colonization with P-fimbriated strains of E coli and receptor availability are important in the pathogenesis of pyelonephritis.