Risk factors for antibiotic-resistant Escherichia coli isolated from hospitalized patients with urinary tract infections: A prospective study

From November 1998 to February 1999 we prospectively evaluated the prevalen ce of resistance to penicillins, cephalosporins, carbapenem, quinolones, am inoglycosides, and trimethoprim-sulfamethoxazole (SXT) in 320 Escherichia c oli isolates isolated from hospitalized patients with acute urinary tract i nfections (UTIs). We also studied for these strains risk factors for resist ance to amoxicillin-clavulanic acid (AMC), fluoroquinolones (FQs), and SXT. Resistance rates were consistent with those from major recent studies repo rted in the literature. Multivariate analyses selected the following factor s as being significantly associated with E. coli resistance: (i) for resist ance to AMC, prior (1 year) UTI (odds ratio [OR] = 2.71, P = 0.006), prior (1 year) urinary catheter (OR = 2.98, P = 0.0025), and prior (6 months) ant ibiotic exposure (OR = 2.68, P = 0.005); (ii) for resistance to FQs male se x (OR = 3.87, P = 0.03), with a trend toward significance for age >65 years (OR = 7.67, P = 0.06) and prior (1 year) UTI (OR = 2.98, P = 0.07); and (i ii) for resistance to SXT, male sex (OR = 1.91, P = 0.046), hospitalization in an intermediate-term care unit (OR = 2.18, P = 0.008), and prior (1 yea r) UTI (OR = 2.03, P = 0.03). Ours results suggest that prior UTI is a comm on risk factor for resistance to the different antibiotics tested. Although few studies on risk factors for E. coli resistance to antibiotics have bee n published, careful interpretation of their findings, taking into consider ation the population, infection site, and period studied, should contribute to the formulation of a better strategy that can be used to overcome antib iotic resistance.