Anti-Bacterial Defense Mechanism of the Urinary Bladder

Abstract

Bacterial adherence to mucosa is thought to be an initial and important stage to cause urinary tract infection. Among some mechanisms of bacterial adherence, the role of fimbriae and its receptor is worthy of notice. In particular, type 1 fimbriae, for which mannose is assumed as a receptor, is reported as the most common type and called “common fimbriae”. Therefore if a certain amount of mannose is present in urine, it will cover the fimbriae of bacteria and competitively block the bacterial adherence to bladder mucosa. As the first step, we tried to detect mannose in urine by high performance liquid chromatography (HPLC). Sugar can be measured by detecting the fluorescence which is produced by a sugar separated by ion exchange, reacting with arginine at high temperature. The results using standard sugar samples should have highly stable retention time and concentration curve with the minimum detectable mannose concentration of 0.02 μg. We investigated mannose in urine from 186 cases. Since the mannose peak was often masked by near unidentified peaks, the peak of mannose could be detected only in 80 cases and its concentration could be measured only in 24 cases. Mannose concentration in the urine of the 24 cases was between 2.6 and 108.7 μg/ml and in most of cases it was lower than 20 μg/ml. Secondaly, we examined the possibility of a mannose in urine to prevent bacterial adherence to mucosa by the hemagglutination test using guinea pig erythrocytes and type 1 fimbriated E. coli. The minimum bacterial concentration to agglutinate 2% guinea pig erythrocytes was studied on 11 strains retaining type 1 fimbriae derived from 26 strains caused acute cystitis. Using the minimum bacterial concentration of 11 strains agglutinating 2% guinea pig erythrocytes, the minimum mannose concentratioin to inhibit agglutination was between 0.6 and 156 μg/ml and, in 7 of 11 strains, it was lower than 20μg/ml. These results indicate that free mannose in urine can prevent the type 1 fimbriae mediating bacterial adherence to mucosa, and a small amount of mannose is considered as one of the antibacterial factors existing in urine. © 1989, THE JAPANESE UROLOGICAL ASSOCIATION. All rights reserved.