In Vitro Antibacterial Activity of Oral Cephalosporins

Summary

The in vitro activity of orally active first generation (cefalexin), second generation (cefaclor and cefuroxime) and third generation (cefdinir, cefixime, ceftibuten, cefpodoxime, cefprozil, and cefetamet) cephalosporins was reviewed. All of these cephalosporins inhibit community-acquired respiratory pathogens (i.e. Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and S. pyogenes) and Neisseriaceae, but have little or no clinically relevant activity against oxacillin-/methicillin-resistant staphylococci, enterococci, Gramnegative rods (i.e. Pseudomonas aeruginosa and Xanthomonas maltophilia), or anaerobic rods (i.e. Bacteroides fragilis and Clostridium species). Cefalexin, cefaclor and cefuroxime are less potent inhibitors and have a narrower spectrum of activity than the third generation cephalosporins reviewed. Among the third generation cephalosporins, cefixime inhibits the broadest spectrum of Enterobacteriaceae, but cefixime, ceftibuten, and cefetamet lack any clinically meaningful antistaphylococcal activity, and cefpodoxime and cefprozil are several dilution-folds less active against staphylococci than cefdinir. Cefdinir matches the potent inhibitory activity of cefixime against the most common community-acquired respiratory tract pathogens and the most common community-acquired Enterobacteriaceae (i.e. Escherichia coli, Proteus mirabilis and Klebsiella pneumoniae). In addition, of the third generation cephalosporins reviewed, cefdinir is the most potent inhibitor of the common community-acquired staphylococcal pathogens, Staphylococcus aureus, coagulase-negative staphylococci and S. saprophyticus. Thus, the spectrum of activity of cefdinir encompasses most clinically significant community-acquired pathogens.