In VitroEvaluation of Faropenem Activity Against Anaerobic Bacteria

Antimicrobial resistance and the management of anaerobic infections

Management of anaerobic infections encompasses surgical procedures, antibacterial therapy and adjuncts. At present, metronidazole, penems, beta-lactam/beta-lactamase inhibitor combinations and chloramphenicol have the highest activity against obligate anaerobes. Tigecycline is a promising new agent. Other antibacterials (e.g., nitazoxanide, moxifloxacin, garenoxacin and ramoplanin) and nonantibiotic agents show potential but need further investigation. The patient's characteristics, mixed anaerobic/aerobic infections, infection sites, bacterial resistance patterns, bactericidal activity of agents and their pharmacokinetics, toxicity and influence on the normal flora should be considered. Susceptibility patterns of anaerobes have become less predictable owing to increasing antibacterial resistance. Emergence of highly virulent or multidrug-resistant strains is challenging the current therapy. To counteract these trends, regular resistance surveillance in anaerobes, rational antibiotic use and evaluation of new treatment alternatives are important.

Faropenem: review of a new oral penem

Faropenem medoxomil is a new orally administered penem antibiotic. Its chiral tetrahydrofuran substituent at position C2 is responsible for its improved chemical stability and reduced CNS effects, compared with imipenem. Faropenem demonstrates broad-spectrum in vitro antimicrobial activity against many Gram-positive and -negative aerobes and anaerobes, and is resistant to hydrolysis by nearly all beta-lactamases, including extended-spectrum beta-lactamases and AmpC beta-lactamases. However, faropenem is not active against methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium, Pseudomonas aeruginosa or Stenotrophomonas maltophilia. Prospective, multicenter, randomized, double-blind, comparative (not vs placebo) clinical trials of acute bacterial sinusitis (ABS), acute exacerbations of chronic bronchitis (AECB), community-acquired pneumonia (CAP) and uncomplicated skin and skin structure infections (uSSSIs) have demonstrated that faropenem medoxomil has equivalent efficacy and safety compared with cefuroxime, clarithromycin, azithromycin, amoxicillin, cefpodoxime and amoxicillin-clavulanate. The evidence supports faropenem medoxomil as a promising new oral beta-lactam with proven efficacy and safety for the treatment of a variety of community-acquired infections. However, the US FDA recently rejected faropenem for all four indications stating that the clinical trials in ABS and AECB should have been performed versus a placebo. In the CAP studies, the FDA stated that they could not be certain of the validity of the study population actually having the disease and for uSSSI, the FDA stated that only a single trial was not adequate evidence of efficacy for this indication.