Ecological behaviors of uropathogenic bacteria in the infected urine were characterized, and they were compared to those in vitro cultivation. The organisms directly collected from the infected urine revealed no piliation, but when they were isolated and cultured in heart infusion broth (HIB), the pili appeared. The pili were identified as Type I pili as examined by immunogold electron microscopy. Although the organisms directly collected from the infected urine did not have pili and did not agglutinate against anti-Type I pili anti-serum, the whole cell lysate analysis by western blotting revealed that the organisms express Type I pili antigen intracellularly. The organisms in some cases revealed a capsule formation in the urine, but it disappeared when cultured in vitro. Hemolytic Escherichia coli were isolated from 9 cases out of 20 with acute cystitis, however, hemolysin was not detected from the infected urine and the organisms. When they were cultured in HIB, all strains produced the hemolysin. The composition of outer membrane proteins (OMPs) of the organisms in the infected urine was clearly different from those in vitro cultivation. As the most prominent finding, a 70 kDa OMP of the organisms in the infected urine disappeared in vitro. Antibacterial activities of several drugs examined in healthy human urine and in HIB were variable from drug to drug. The mean value of minimum inhibitory concentration (MIC) of ofloxasin was 25 times higher in the urine than in HIB, whereas the MIC of erythromycin was almost equal in both conditions.
