In vitro activity of cefdinir (FK 482, PD 134393, CI-983): a new orally active cephalosporin.

Cefdinir is a new orally active cephalosporin which is undergoing in vitro and in vivo evaluations. Using the standard agar dilution method we compared the in vitro activity of this drug with other beta-lactam antibiotics against clinical isolates or Enterobacteriaceae (625 strains), Pseudomonas aeruginosa (68 strains), Xanthomonas maltophilia (36 strains), Acinetobacter (52 strains), Aeromonas hydrophilia (47 strains), staphylococci (364 strains) and enterococci (50 strains). Against most members of Enterobacteriaceae, Acinetobacter and A. hydrophilia, cefdinir showed excellent activity, inhibiting 94% of these isolates at < or = 32 micrograms/ml. Like other oral drugs of its class, it had little activity against P. aeruginosa and X. maltophilia. All the 120 isolates of methicillin-susceptible Staphylococcus aureus were inhibited by < 1.0 microgram/ml of cefdinir whereas 80% of methicillin-resistant S. aureus had a minimum inhibitory concentration of > 32 micrograms/ml. Of the 50 isolates of enterococci tested, 94% were inhibited by < or = 16.0 micrograms/ml of cefdinir. Against Enterobacteriaceae, its activity was superior to any oral drug tested. With the exception of vancomycin, the in vitro activity of cefdinir was superior or comparable to other antibiotics tested against methicillin-susceptible S. aureus, coagulase-negative staphylococci and enterococci.