Adherence of Gram-Negative Uropathogens to Human Uroepithelial Cells

Abstract

The adherence of several gram-negative uropathogens to human uroepithelial cells was examined with scanning and transmission electron microscopy, and in vitro adhesion assays. The bacteria studied demonstrated different extracellular structures: fimbria and glycocalyx. Human uroepithelial cells were obtained from a bladder tumor cell line (T-24) and from different groups of patients, including those with no history of urinary tract infection (controls), recurrent urinary tract infection, acute cystitis and bladder tumors before and after bacillus Calmette-Guerin therapy. Results from these comparative studies showed that bacteria with extracellular structures adhered better than those bacteria without extracellular structures. It also was shown that uroepithelial cells obtained from patients with recurrent urinary tract infection and with acute cystitis were more susceptible to bacterial adherence than the uroepithelial cells of the controls (there were significant increases of 2 to 5-fold in mean adherence in the former 2 groups, p equals 0.015 and 0.002). There was no significant difference in bacterial adherence between the T-24 cells and the bladder tumor cells before bacillus Calmette-Guerin treatment. However, in both groups after treatment with bacillus Calmette-Guerin the mean adherence increased 2 to 4-fold (p equals 3 times 10−5). A survey of 29 bladder tumor patients also showed a 5-fold increase in the incidence of acquired urinary tract infection after bacillus Calmette-Guerin therapy. These results reveal a correlation between bacterial adherence and urinary tract infection, and suggest that bacterial adherence to uroepithelial cells depends upon the bacterial extracellular structures and the source of the uroepithelial cells.