Epidemiological investigation of fluoroquinolone resistance in infections due to extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae

The incidence of infections due to extended-spectrum beta -lactamase (ESBL) -producing Escherichia coli and Klebsiella pneumoniae (ESBL-EK) has increas ed markedly in recent years. Treatment is difficult because of frequent mul tidrug resistance. Although fluoroquinolones offer effective therapy for ES BL-EK infections, their usefulness is threatened by increasing fluoroquinol one resistance. To identify risk factors for fluoroquinolone resistance in ESBL-EK infections, a case-control study of all patients with ESBL-EK infec tions from 1 June 1997 through 30 September 1998 was conducted. Of 77 ESBL- EK infections, 43 (55.8%) were resistant to fluoroquinolones. Independent r isk factors for fluoroquinolone resistance were fluoroquinolone use (odds r atio [OR], 11.20; 95% confidence interval [CI], 1.99-63.19), aminoglycoside use (OR, 5.83; 95% CI, 1.12-30.43), and long-term care facility residence (OR, 3.39; 95% CI, 1.06-10.83). The genotypes of fluoroquinolone-resistant ESBL-EK isolates were closely related. Efforts should be directed at modifi cation of these risk factors to preserve the utility of fluoroquinolones in the treatment of ESBL-EK infections.