Antimicrobial activity of cefepime tested against Bush group I beta-lactamase-producing strains resistant to ceftazidime. A multilaboratory national and international clinical isolate study.

The potency of cefepime, a parenteral aminothiazolyl methoxyimino cephalosporin, was assessed against 256 ceftazidime-resistant Gram-negative bacilli from five medical centers in the United States. In addition, cefepime activity was compared with that of ciprofloxacin and imipenem against 506 ceftazidime-resistant Gram-negative bacilli collected during an 11-medical-center international study. All US clinical isolates were susceptible (< or = 8 micrograms/ml) to cefepime except Enterobacter cloacae (94% susceptible) and Pseudomonas aeruginosa (19% susceptible). Enterobacteriaceae isolates from the 11-nation sample were > 80% cefepime susceptible with the exception of those from Brazil (48% susceptible) and Italy (55% susceptible). These international, enteric isolates were also very susceptible to ciprofloxacin (55%-100% susceptible) and imipenem (84%-100% susceptible). Nonenteric organisms (Pseudomonas, Xanthomonas, and Acinetobacter) from the same international locations had overall rates of susceptibility of 47% for ciprofloxacin, 28% for imipenem, and only 5% for cefepime. Cross-resistance between the broad-spectrum cephalosporins (cefepime or ceftazidime) with either imipenem or ciprofloxacin was incomplete. Cefepime appears to have a spectrum of use against a significant number of contemporary, ceftazidime-resistant Gram-negative bacillus isolates worldwide.