Antimicrobial activity of gatifloxacin compared to seven other compounds tested against gram-positive organisms isolated at 10 cancer-treatment centers.

Gram-positive bacterial pathogens are important causes of disease in cancer patients and are becoming increasingly resistant to available antimicrobial agents. We examined the in vitro activity of gatifloxacin, a new fluoroquinolone, compared with other quinolones, ceftazidime, and traditional Gram-positive-active agents tested against pathogens isolated from patients at 10 cancer treatment hospitals in the United States. A total of 1,128 Gram-positive isolates were tested by the E-test method (AB BIODISK, Solna, Sweden) with results validated by concurrent quality control strain analysis. Gatifloxacin was more potent than either ciprofloxacin or levofloxacin against all Gram-positive species. Vancomycin was the most active agent tested against all species except Bacillus spp., which were more susceptible to the fluoroquinolones. When tested against these Gram-positive pathogens from patients with cancer, the spectrum of gatifloxacin was also greater than that of levofloxacin and ciprofloxacin. Gatifloxacin may have a role as part of prophylactic or therapeutic antimicrobial regimens for selected cancer patients with Gram-positive infections.