Antibiotic resistance of Escherichia coli from community-acquired urinary tract infections in relation to demographic and clinical data

This prospective study determined the antibiotic susceptibility of 164 isolates of Escherichia coli from the urine of 164 patients (112 female, 52 male; mean age of 54.12 years) with community-acquired urinary tract infection (UTI). Half of the isolates were from uncomplicated UTI and half from complicated UTI (52 males and 34 females). Overall, 57.3% of isolates were resistant to ampicillin, 25% to co-trimoxazole, 20.1% to nalidixic acid, 14% to norfloxacin and ciprofloxacin, and 0% to fosfomycin and nitrofurantoin. Of the 82 isolates from complicated UTI, 16 (19.5%) were resistant to norfloxacin and ciprofloxacin, compared with seven (8.5%) from uncomplicated UTI (p 0.043). Isolates from patients aged >50 years were significantly more resistant than those from patients aged <50 years for nalidixic acid (p 0.007) and the fluoroquinolones tested (p 0.015). Resistance to fluoroquinolones was 25% (13/52) in males and 9% (10/112) in females (p 0.006). For patients with and without previous antimicrobial therapy, there was a significant difference only for resistance to nalidixic acid (p < 0.001) and the fluoroquinolones (p 0.011). There were adequate susceptibility rates to fosfomycin, nitrofurantoin and the fluoroquinolones for empirical use in the treatment of acute uncomplicated UTI. In order to interpret cumulative susceptibility data from the primary healthcare setting, it is necessary to take into account the type of UTI (uncomplicated vs. complicated), previous antimicrobial therapy, and the sex and age of each patient.