Reduced requirement for antibiotic therapy targeting gram-negative organisms in febrile, neutropenic patients with cancer who are receiving antibacterial chemoprophylaxis with oral quinolones.

An open, nonrandomized, phase 2 study of 53 adult patients who had 60 neutropenic episodes was conducted to determine if quinolone antibacterial prophylaxis could reduce the need during febrile episodes for parenteral therapy directed at gram-negative organisms. Suspected infections among recipients of quinolones were treated empirically with vancomycin and ceftazidime; therapy with the latter was discontinued after 24-48 hours in the absence of infection due to gram-negative organisms. In five neutropenic episodes, patients had no fever or infection. An aerobic gram-negative bacillus was isolated during only 1 (1.8%) of 55 febrile episodes. Febrile episodes occurred at a median of day 15 of cytotoxic therapy. Vancomycin monotherapy was successful in 22 (50%) of 44 evaluable cases. Modification of the vancomycin regimen by the addition of metronidazole or rifampin increased the response rate to 40 (91%) of 44. Response occurred after a median of 4.5 days. Parenteral empirical therapy with amphotericin B was required in only 3 (7%) of 44 cases. The study strategy safely permitted a reduction in the amount and duration of antibiotic therapy directed against gram-negative organisms in febrile neutropenic patients.