Quinolone resistance in female outpatient urinary tract isolates of Escherichia coli: age-related differences

Se recogieron a lo largo de un año (noviembre de 2003 a octubre de 2004) 2230 aislamientos de Escherichia coli de pacientes con infección urinaria adquirida en la comunidad procedentes de 20 laboratorios microbiológicos de toda España, que fueron enviados a un laboratorio central de referencia para realizar la confirmación del patógeno y las pruebas de sensibilidad antibacteriana, mediante el método de dilución en agar. El principal objetivo fue evaluar la resistencia a los antimicrobianos más prescritos en las cistitis agudas, en relación con la edad. Se utilizó el test de χ2 bilateral para valorar las diferencias de la resistencia entre los dos grupos de edad (≤65 años y ≥65 años). E. coli mostró una elevada resistencia a la ampicilina (52,1%), el cotrimoxazol (26%) y las quinolonas (18%), mientras que a amoxicilina-ácido clavulánico, cefuroxima-axetilo y fosfomicina fue inferior al 3%. En las mujeres mayores de 65 años, la resistencia al ciprofloxacino alcanzó el 29%, frente al 13% en las mujeres por debajo de esa edad (p 65 años se asoció con mayores tasas de resistencia al ciprofloxacino (29%). Estos resultados deberían tenerse en cuenta cuando se recomienda un tratamiento antimicrobiano empírico en mujeres con cistitis aguda comunitaria

During a 1-year period, from November 2003 to October 2004, urinary Escherichia coli isolates were collected from 20 clinical microbiology laboratories across Spain. The main objective was to assess the resistance of E. coli to the antimicrobials most commonly prescribed for community- acquired urinary tract infections depending on the patient’s age. A total of 2,230 valid E. coli strains from female outpatients were isolated and sent to a single central reference laboratory for confirmation and susceptibility testing using an agar dilution method. A two-sided chi-squared test was used to assess the differences in resistance between age groups (≤65 and >65 years). E. coli resistance was found to be more common to ampicillin (52.1%), cotrimoxazole (26%) and quinolones (18%), whereas resistance to amoxicillin-clavulanic acid, cefuroxime axetil and fosfomycin were below 3%. In women older than 65 years, resistance to ciprofloxacin reached up to 29% compared with 13% of those in the under 65 age group (p <0.001). For cotrimozaxole, rates were 32% vs. 23% (p <0.001) and for ampicillin 56% vs. 50% (p=0.02), respectively. It was concluded that fosfomycin, amoxicillin-clavulanic acid and cefuroxime axetil are the most suitable antimicrobials for empirical treatment in Spain given the high 18% and 26% resistance rates to quinolones and cotrimoxazole, respectively. Being older than 65 years of age was associated with higher resistance rates to ciprofloxacin (29%). These results should be considered when recommending empirical therapy for acute cystitis in women

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.