Comparison of the antibacterial effect of uroepithelial cells from healthy donors and children with asymptomatic bacteriuria.

Bacterial attachment to uroepithelial cells (UEC) and the effect of UEC on bacterial growth was investigated in 15 healthy persons and 12 patients suffering from asymptomatic bacteriuria (ABU) with recurrent urinary tract infections (UTI). Desquamated UEC and mannose-resistant Escherichia coli were co-cultivated for up to 90 min. While no difference in bacterial adherence was observed between healthy controls and patients, 33.4% of the bacteria attached to normal UEC were found to be dead under microscopic evaluation (acridine orange staining), whereas no killing effect could be observed in patients' UEC 5 min after the onset of incubation. This phenomenon was confirmed by investigating the E. coli growth rate in the presence of UEC, measured by counting bacterial colony forming units (CFU) on agar plates. While E. coli showed exponential growth in RPMI medium, the addition of normal UEC suppressed bacterial growth (P less than 0.01). UEC from patients with ABU, however, did not show this effect. It has been concluded that bacterial adhesion may initiate an epithelial defence function, present in healthy controls and lacking in ABU patients.