Recurrent urinary tract infections caused by Escherichia coli

Abstract number: o394

Gualandris  S., Endimiani  A., Brigante  G., Luzzaro  F., Toniolo  A.


Escherichia coli is the most common pathogen isolated from urinary tract infections (UTI). These infections occur frequently in healthy women. Of them, 25% are reinfected within six months after the first UTI episode. Fluoroquinolones (FQ) and trimethoprim-sulfamethoxazole (SXT) are the most frequent empirical treatments used for UTI. Notably, underestimate UTI can progress to serious illnesses, as bloodstream infections (BSI).


All urinary samples collected during 2004 at our institution were studied retrospectively. Identification and antimicrobial susceptibility tests (AST) were achieved using the Phoenix system (Becton Dickinson, Diagnostic Systems, Sparks, MD). The Epicenter (Becton Dickinson) and the Powerlab (Unitech, Milano) systems were used to obtain clinical and microbiological data. "Reinfection" was defined as a new UTI occurring at least two weeks after the first infectious episode.


During the study period, 3706 patients diagnosed with UTI due to E. coli were observed. Reinfections were found in 495 (13.4%) patients. The majority of them were women (85.0%) and with community-acquired UTI (91.5%). On the average, 2.5 UTI/year for patient were detected. The majority of patients had 2 or 3 episodes/year (71.5% and 16.5%, respectively). The most prevalent age groups were 60–70 years, and 70–80 years (19.1% and 23%, respectively). With regard to the first isolates that were responsible of recurrent UTI, AST results showed the following resistance incidences: FQ (23.4%), SXT (31.3%), ampicillin (50.1%), amoxicillin/clavulanate (15.9%), and ceftriaxone (1.6%). Isolates causing subsequent infections were characterized by increased resistance: FQ (29.4%), SXT (36.5%), ampicillin (55.9%), amoxicillin/clavulanate (21.8%), and ceftriaxone (5.8%). Patients with recurrent UTI were more liable to develop BSI than patients having only one infectious episode (2.0% and 0.6%, respectively).


E. coli recurrent UTI episodes occur commonly in aged woman with community-acquired infections. Recurrent infections may evolve to BSI more frequently than patients showing single UTI episodes. The high incidence of isolates resistant to antimicrobials (e.g., FQ and SXT) underlines the ineffectiveness to plan an adequate empirical therapy. Therefore, for recurrent UTI is opportune to use the more suitable therapy based on etiological and AST results.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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