Lack of adherence to epithelial cells by freshly isolated urinary pathogens

Urinary pathogens isolated from twenty patients who had urinary tract infections (UTI) with or without symptoms were tested for adhesion to normal buccal and uroepithelial cells, and for their ability to agglutinate guinea pig and human erythrocytes. The tests were done on initial isolation and after repeated subculture in urine and nutrient broth. Of the fresh isolates all but one were non-fimbriate and all but one were non-adherent in each test system, but after subculture in broth fourteen of the twenty strains developed fimbriae and seventeen became adherent to buccal cells. Five strains remained non-adherent to uroepithelial cells despite repeated subculture, and there was no correlation between adhesion of the subcultured organisms and clinical severity of UTI. These observations suggest that adherence is not a virulence factor for bacteria once they have entered the urinary tract, and that previous claims for the existence of a correlation between the adherence properties of uropathogens and clinical severity of UTI are unfounded.