The virulence factors and antibiotic sensitivities of Escherichia coli isolated from recurrent urinary tract infections

OBJECTIVE: We determined the antibiotic sensitivities of uropathogenic Escherichia coli (UPEC) strains isolated from the urine of patients who have recurrent urinary tract infections (UTIs).

METHODS: Our study was carried out between November 2000 and January 2002 at the Infectious Diseases Clinic, Istanbul Haydarpasa Numune Hospital, Istanbul, Turkey. We compared the virulence factors (fimbrial adhesion, hemolysin production, motility property) of 50 strains of Escherichia coli (E. coli) isolated from urine with the same properties of 25 strains of E. coli isolated from stool specimens of healthy individuals. In addition, we detected the virulence factors of UPEC strains using a microbiological and biochemical methods and by using disk diffusion method, we were able to investigate the sensitivity of the strains to the antimicrobials.

RESULTS: We found the level of mannose-resistant (MR) fimbriae bearing in the UPEC strains to be significantly higher than that in the controls (odds ratio=10.27, p<0.001). The difference in mannose-resistant hemoagglutination (MRHA) and mannose sensitive hemoagglutination (MSHA) bearing levels in UPEC strains were rather high. This difference was regarded as significant in terms of showing the virulence of fimbriae bearing strains (odds ratio=29.03, p<0.001).

CONCLUSION: Our study demonstrates that strains with MR fimbriae have a rather high virulence (p<0.001), and that a combination of MR+MS fimbriae increased that virulence (p<0.001). As MR strains have a greater adhesive property, the determination of MR fimbriae bearing as high shows that fimbriae bearing plays an important role in widespread and resistant strains, especially in recurrent UTIs such as in our study. In addition, hemolysin capability was also a virulence factor in recurrent UTIs (p<0.01). In addition, the sensitivity of the strains to the antimicrobials appeared in the following order; imipenem 93%, norfloxacin 89%, ciprofloxacin 85%, netilmicin 80%, amikacin 78%, ceftriaxone 74%, gentamicin 72%, nitrofurantoin 71%, ampicillin-sulbactam 60%, amoxicillin-clavulanate 58%, Trimethoprim/sulfamethoxazole 45%, ampicillin 35%.