Objetives:

In a population-based study we assessed the antibiotic resistance of E. coli from community-acquired ITU considering demographic and clinical data.

Methods:

This prospective study considered 164 isolates of E. coli (one per patient) from urine samples of patients with community-acquired UTI diagnosed in the Emergency Service of our hospital. The antibiotic susceptibility was determined for ampicillin, gentamicin, fosfomycin, nitrofurantoin, cefazolin, nalidixic acid, norfloxacin, ciprofloxacin and cotrimoxazole. The clinical records of the 164 patients were reviewed and a protocol was filled out for each one.

Results:

The 164 E. coli isolated from urine proceeded from 112 women and 52 males with a mean age of 54.12 years (SD = 21.15 years). After analysing the clinical records it was noted that 82 (50%) proceeded from uncomplicated UTI and 82 (50%) from complicated UTI (52 males and 34 females).

Globally, 57.3% of the strains were resistant to ampicillin, 25.0% to cotrimoxazole, 20.1% to nalidixic acid, 14% to norfloxacin and ciprofloxacin, and 0% to fosfomycin and nitrofurantoin. Of the 82 strains proceeding from complicated UTI, 16 (19.5%) were resistant to norfloxacin and ciprofloxacin whereas only seven (8.5%) from uncomplicated UTI were resistant (P = 0.043).

Significant differences for the quinolones were found when the resistance of isolates from patients >=50 years were compared with those from patients <50 years: 28% (25/90) vs. 11% (8/74) (P = 0.007) for nalidixic acid, and 20% (18/90) vs. 6.7% (5/74) (P = 0.015) for the fluoroquinolones tested.

Comparison of the resistance by sex showed statistically significant differences in cefazolin, 11.5% (6/52) in males compared with 1.7% (2/112) in women (P = 0.013); and in fluoroquinolones where the resistance was 25% (13/52) in males and 9% (10/112) in females (P = 0.006).

Conclusions:

In acute uncomplicated UTI fosfomycin, nitrofurantoin, and the fluoroquinolones show adequate rates of susceptibility for empirical use in our area. For optimal interpretation of susceptibility in cumulative data from the Primary Health setting it is necessary to take into account the type of UTI (uncomplicated vs. complicated), the sex and age of each patient.