Low virulence of Escherichia coli strains causing urinary tract infection in renal disease patients

The distribution of urinary bacterial species was determined and the virule nce factors of Escherichia coli urinary strains analysed by molecular and p henotyping methods in episodes of urinary tract infection in renal disease patients (n = 68) in comparison with other immunocompromised patients (n = 59) and nonimmunocompromised patients (n = 21). Escherichia coli was isolat ed in 116 (78%) of the 148 patients, being the species most frequently isol ated in all groups (75% of renal disease patients, 76% of other immunocompr omised patients, 95% of nonimmunocompromised patients). All other pathogens showed a similar distribution in the renal disease and other immunocomprom ised patient groups. All virulence factors of Escherichia coli tested for ( genes for G adhesins, expression of MR adhesins, production of haemolysin, presence of certain O and K antigens) were found more often in non-immunoco mpromised than in immunocompromised patients. The factors allowing the high est degree of discrimination between immunocompromised and non-immunocompro mised patients were the prevalence of genes for G adhesins (35% vs. 65%) an d expression of MR adhesins (32% vs. 55%). it is concluded that there is a lower prevalence of G adhesins and MR adhesins in Escherichia coli strains from immunocompromised patients than non-immunocompromised patients, sugges ting that less virulent Escherichia coli strains may cause urinary tract in fections more frequently in renal disease patients and other immunocompromi sed patients. Moreover, the spectrum of urinary pathogens other than Escher ichia coli is similar in both immunocompromised patient groups investigated .