Epidemiology, risk factors and comorbidity for urinary tract infections caused by extended-spectrum beta-lactamase (ESBL)-producing enterobacteria.

AIM: Urinary tract infection (UTI) caused by resistant bacteria is becoming more prevalent. We investigate characteristics and associated risk factors for UTIs resulting from extended-spectrum beta-lactamase (ESBL)-producing enterobacteria.

METHODS: Retrospective study of urinary tract isolates of ESBL-producing enterobacteria in adults (2009 and 2010). We included 400 patients and 103 controls (UTI caused by non-ESBL Escherichia coli). Clinical and demographic information was obtained from medical records. Comorbidity was evaluated using Charlson Index (CI). Strains were identified using VITEK 2 system.

RESULTS: A total of 400 isolates were obtained (93%E. coli and 7%Klebsiella spp). In 2009, 6% of cultures were ESBL-producing E. coli and 7% in 2010. 37% of patients were men and 81% were aged ≥60years. CI was 2.3±1.8 (high comorbidity: 42.8%). 41.5% of strains were susceptible to amoxicillin-clavulanate, 85.8% to fosfomycin and 15.5% to ciprofloxacin. The total number of ESBL E. coli positive urine cultures during hospital admission was 97 and, compared with 103 controls, risk factors for UTI caused by ESBL- E. coli strains in hospitalised patients were nursing home residence (p<0.001), diabetes (p=0.032), recurrent UTI (p=0.032) and high comorbidity (p=0.002). In addition, these infections were associated with more symptoms (p<0.001) and longer admission (p=0.004).

CONCLUSIONS: Urinary tract infection caused by ESBL are a serious problem and identifying risk factors facilitates early detection and improved prognosis. Male sex, hospitalisation, institutionalisation, diabetes, recurrent UTI and comorbidity were risk factors and were associated with more symptoms and longer hospital stay.