Catheter-associated urinary tract infections: distribution of uropathogens and patterns of antimicrobial resistance in an Italian hospital (2000–2006)

Abstract number: 1733_1435

Bonadio M., Tartaglia T., Fondelli S., Andreotti G.

Objectives: To evaluate some risk factors which could affect the isolation rates of various uropathogens and their in vitro antibiotic resistance in patients with catheter-associated urinary tract infection (CAUTI) at an Italian teaching hospital.

Methods: A prospective study was conducted in an Urinary Tract Infections Clinic at Pisa General Hospital. Two hundred twenty-nine patients (72 males and 157 females) with documented CAUTI (≥10⁴ CFU in a catheter sample of urine) were enrolled from January 2000 to October 2006. One hundred eighty-four (81.3%) of all patients were over the age of 70. The distribution of uropathogens and their in vitro susceptibility to antimicrobials were evaluated.

Results: The causative microorganism of CAUTIs were the following: Escherichia coli (28.4%), Enterococcus spp. (18.3%), Pseudomonas spp. (12.6%), KES group spp. (10.0%), fungi (10.0%). E. coli was more frequently isolated in women than in men (31.8% vs 20.8% respectively; p = 0.1). An increased trend of fungi (mostly Candida spp.) isolation rate throughout the whole study period was observed. E. coli patterns of antibiotic resistance were the following ones: cotrimoxazole (35.0%), ampicillin (51.6%), ciprofloxacin (18.6%), nitrofurantoin (12.7%). Enterococci were all susceptible to vancomycin and teicoplanin. Pseudomonas spp. were frequently resistant to ciprofloxacin (40.7%); the most active antibiotics against Pseudomonas were imipenem, amikacin, piperacillin-tazobactam and aztreonam. E. coli showed a significant increase of resistance (p = 0.03) to ciprofloxacin during the study period. E. coli and Enterococcus spp. isolated in patients who received antimicrobials within the 2 months prior to their enrollment were often in vitro resistant to ciprofloxacin and gentamycin. Nitrofurantoin remained the most active drug against E. coli and Enterococcus in both groups of patients whether or not they received antimicrobial drugs.

Conclusions: The type of uropathogens associated with CAUTI have changed over the last 7 yrs at our hospital. The gender of patients seems to influence the isolation rate of E. coli. An increased trend of isolation rate of fungi has been observed during the study period. A previous antimicrobial treatment in patients with CAUTI increases the risk of isolation of uropathogens resistant to the antimicrobials.