Nonfermentative gram-negative bacilli in cancer patients: increasing frequency of infection and antimicrobial susceptibility of clinical isolates to fluoroquinolones.

Despite a decline in the frequency of gram-negative infections in cancer patients, there has been an increase in the proportion of such infections caused by nonfermentative gram-negative bacilli (NFGNB). We tested the in vitro activity of several quinolones against NFGNB isolated from cancer patients between February 2000 and February 2003, using a broth microdilution method. Ciprofloxacin was the most potent agent tested against Pseudomonas aeruginosa, although only 80% of isolates were susceptible to it. The newer quinolones (gatifloxacin, moxifloxacin, and garenoxacin) had better activity than ofloxacin, levofloxacin, and ciprofloxacin, against many other nonfermenters (Stenotrophomonas maltophilia, P. fluorescens, and P. putida).