Bacteriology and ultrastructure of the bladder in patients with urinary tract infections

Tissue obtained by biopsy of the bladder from 33 patients with various urinary tract symptoms was studied by conventional bacteriological techniques and by scanning electron microscopy (SEM). All the patients had recurrent urinary tract symptoms which had not completely responded to antibiotic therapy. Eleven of the patients had greater than or equal to 10(8) colony-forming units (CFU) of bacteria/1 urine; six had between 10(6) and 10(7) CFU/1, and 16 were abacteruric. Bacteria were isolated, however, from the tissue obtained by biopsy from eight of the 16 patients with sterile urine and bacteria were seen on the uro-epithelium in 14 of these patients. By comparison, in all samples of tissue obtained from the 11 patients with greater than or equal to 10(8) CFU/1 of urine bacteria were seen on the uro-epithelium and from nine of these, bacteria were subsequently grown. Fastidious organisms were not isolated from any of the patients. The uro-epithelium of all those studied was also shown to be grossly disrupted with increased disturbance and loss of the epithelial cells when compared with tissue obtained from uninfected patients. The degree of uro-epithelial disturbance was greatest in patients with histories of urinary tract infections lasting more than 4 months. The findings suggest that bacteriological examination of the urine does not always reflect bacterial infection on the bladder surface nor disruption of the uro-epithelium. The changes on the bladder surface may explain the patients' symptoms. In view of the results, a scheme is proposed that explains the development of symptoms in patients with urinary tract and bladder infections.