Modified method for studying bacterial adhesion to isolated uroepithelial cells and uromucoid

Several problems have been encountered with the application of published methods for the study of bacterial adherence to isolated uroepithelial cells. Of particular importance is the observation that urinary mucus traps some organisms but not others. Established techniques have been modified to overcome these difficulties and so allow a distinction to be made between adherence of bacteria to uromucoid and adherence to uroepithelial cells per se. The modified method was used to assess the ability of 34 urinary isolates of Escherichia coli to adhere to uroepithelial cells, uromucoid, or both after serial subculture in nutrient broth. The ability of the organisms to produce mannose-sensitive (MS) agglutination of guinea pig erythrocytes and mannose-resistant (MR) agglutination of human erythrocytes was tested simultaneously and taken to indicate possession of MS type 1 fimbriae andated MR fimbriae, respectively. Results revealed that only MS-positive organisms adhered to uromucoid (P less than 0.001), whereas MR-positive strains showed significantly greater attachment to uroepithelial cells than did MR-negative strains (P less than 0.05). These observations demand that published data derived from the use of a methodology in which no differentiation can be made between adherence to uromucoid and adherence to cells should be interpreted with caution.