EMERGENCE OF QUINOLONE-RESISTANT ESCHERICHIA-COLI BACTEREMIA IN NEUTROPENIC PATIENTS WITH CANCER WHO HAVE RECEIVED PROPHYLACTIC NORFLOXACIN

Between January 1988 and December 1992, 35 episodes of Escherichia col i bacteremia were identified in a series of 230 cases of bacteremia in neutropenic patients with cancer. Thirteen episodes (37%) were due to quinolone-resistant strains. Minimal inhibitory concentrations of nor floxacin ranged from 16 mu g/mL to 128 mu g/mL, and those of ciproflox acin from 8 mu g/mL to 64 mu g/mL. The incidence of bacteremia due to quinolone-resistant E. coli increased from zero episodes per 1,000 hos pital admissions in 1988 to four episodes per 1,000 admissions in 1992 (P = .018). To identify risk factors for quinolone-resistant E. coli bacteremia, we compared episodes of quinolone-resistant and quinolone- susceptible E. coli bacteremia. Among the variables analyzed, prophyla xis with norfloxacin was the only factor significantly associated with the development of quinolone-resistant E. coli bacteremia; 13 of 13 p atients with bacteremia due to resistant strains received norfloxacin, whereas only one (5%) of 22 patients with bacteremia due to susceptib le strains did (P < .001). According to our data, neutropenic patients with cancer who receive fluoroquinolone prophylaxis may be at risk of developing E. coli bacteremia due to quinolone-resistant strains.