The outcome of patients with urinary tract infections caused by extended spectrum β-lactamases (ESBL)-producing bacteria (cases) was compared with that of matched controls with urinary tract infections caused by non-extended spectrum β-lactamases-producing isolates. Significantly, more case patients received inappropriate empiric therapy than controls. Nevertheless, clinical and microbiologic outcomes as well as formation of renal scars did not differ between the 2 groups.

dUrinary tract infections (UTIs) due to extended-spectrum-␤-lactamase (ESBL)-producing Enterobacteriaceae in children are becoming more frequent, and they are commonly treated initially with a second-or third-generation cephalosporin. We developed a murine model of ascending UTI caused by ESBL-producing Escherichia coli. Using this model, we investigated the renal bacterial burden, interleukin-6 (IL-6) expression, and histopathological alterations caused by ESBL-and non-ESBL-producing bacteria after 1, 2, or 6 days with or without ceftriaxone therapy. The renal bacterial burden, IL-6 concentration, and histological inflammatory lesions were not significantly different between mice infected with ESBL-and non-ESBL-producing bacteria without treatment at any of the time points examined. Following ceftriaxone administration, the bacterial burden was eliminated in the kidneys of mice infected with ESBL-and non-ESBL-producing bacteria on the 6th postinfection day. The histological analysis demonstrated that among mice treated with ceftriaxone, those infected with ESBL-producing bacteria had more profound renal alterations than those infected with non-ESBL-producing bacteria on the 6th day (P < 0.001). In comparison, microbiological outcomes did not differ significantly between mice infected with ESBL-and non-ESBL-producing bacteria at any of the time points examined. The effectiveness of ceftriaxone in mice with UTIs due to ESBL-producing E. coli may have therapeutic implications; it is, however, hampered by limited activity on the histopathological lesions, a finding that needs further investigation. E xtended-spectrum ␤-lactamases (ESBL) are enzymes that hydrolyze penicillins, cephalosporins of the first, second, and third generations, and aztreonam and are mostly produced by Enterobacteriaceae (1, 2). Since their discovery, ESBL enzymes have spread in many microorganisms and have caused a wide variety of infections in all age groups worldwide (3, 4). Infections caused by ESBL-producing bacteria are difficult to treat, as these bacteria are generally resistant to the empirical therapy commonly used (5-13). Infections caused by such bacteria are believed to have worse outcomes than infections caused by non-ESBL-producing bacteria (5, 6, 9). It is not clear whether the worse outcomes of infections caused by ESBL-producing bacteria are attributable to the greater pathogenicity of the invading bacteria, to inappropriate initial therapy, or to both.Urinary tract infections (UTIs) are common causes of morbidity in children and adults (14-16). UTIs caused by ESBL-producing bacteria have been spreading in both nosocomial settings and in the community (17-19). It is unclear whether UTIs caused by ESBL-producing bacteria share the unfavorable outcomes of other ESBL infections, such as sepsis or pneumonia. We developed an ascending UTI model in BALB/c mice in order to study the microbiological, inflammatory, and immunological aspects of UTIs caused by ESBL-producing bacteria and the effect of ceftriaxone, a third-generation ce...

While SXT and 2GC appear to be equally efficacious as UTI prophylaxis in children, the latter exert a broader effect on patients' flora and development of bacterial resistance, suggesting that SXT may be more appropriate for UTI prophylaxis than 2GC.