Antimicrobial activity and beta-lactamase stability of BMY-28232, parent compound of an oral cephalosporin

Cefixime. A review of its therapeutic efficacy in lower respiratory tract infections

Cefixime is an orally active third generation cephalosporin with in vitro antibacterial activity against most important lower respiratory pathogens. The drug is active against Haemophilus influenzae, Moraxella catarrhalis and penicillin-susceptible Streptococcus pneumoniae but not Staphylococcus aureus. Cefixime has a long elimination half-life (3 hours compared with 0.5 hours for cefaclor and 1.5 hours for cefalexin), which allows once daily administration. Several trials have established the clinical efficacy of the drug in patients with lower respiratory tract infection (LRTI). In comparative studies cefixime had similar efficacy to amoxicillin +/- clavulanic acid, cefaclor, cefalexin, cefuroxime axetil and clarithromycin. Trials evaluating the efficacy of cefixime as the oral component of intravenous to oral switch therapy have produced promising preliminary results although further carefully designed trials are needed in this area. As with certain other drugs of its class, gastrointestinal disturbances are the most frequently reported adverse events in patients taking cefixime and cases of pseudomembranous colitis have been reported. Thus, cefixime is an effective treatment for mild to moderate LRTI and may have a role as the oral component of intravenous to oral switch therapy although further well designed studies are needed to confirm initial favourable results in this important emerging area of antibacterial therapy.

Current status of bacterial resistance to third-generation cephalosporins

A review of the evolution of bacterial resistance to third-generation cephalosporins is presented, focusing mainly on the prototypical member of this group-cefotaxime. Third-generation cephalosporins generally remain highly active against most Enterobacteriaceae, staphylococci, streptococci, Haemophilus, and Neisseriaceae. Only enterobacteria with a high frequency of mutant derepressed strains that hyperproduce chromosomally mediated beta-lactamase, Pseudomonas spp., and some glucose nonfermenter Gram-negative bacilli have demonstrated increased levels of resistance. The significance of derepressed strains and of the recently described extended-spectrum, plasmid-mediated beta-lactamases to the usefulness of the third-generation cephalosporins is discussed.