Cefditoren in vitro activity and spectrum: a review of international studies using reference methods

Cefditoren, a broad-spectrum orally administered cephalosporin ester, has documented in vitro efficacy against many Gram-positive and -negative pathogens and stability against clinically important beta-lactamases. We have reviewed the microbiology and the pharmacokinetic/pharmacodynamic literature regarding the spectrum and potency of this newer agent against the major etiologic agents of community-acquired respiratory infection, (Streptococcus pneumoniae, Hemophilus influenzae and Moraxella catarrhalis), as well as the Enterobacteriaceae and non-enteric Gram-negative bacilli, staphylococci, and other aerobic and anaerobic Gram-positive cocci. The level of cefditoren activity against S. pneumoniae (MIC(90,) 0.5 microg/mL) was superior to all marketed oral cephalosporins and at least equal to amoxicillin +/- clavulanate. H. influenzae (MIC(90,) 0.016-0.03 microg/mL) and M. catarrhalis (MIC(90,) 0.06-0.5 microg/mL) were also very susceptible to cefditoren. In contrast to cefixime and ceftibuten, cefditoren was active against oxacillin-susceptible staphylococci (MIC(90,) < or = 1 microg/mL) at a level comparable to cefuroxime axetil, cefaclor or cefprozil. Enterococci, Pseudomonas aeruginosa and most anaerobes (Gram-negative) were not cefditoren-susceptible, but most Enterobacteriaceae, beta-haemolytic and viridans group streptococci were highly susceptible. Furthermore, an overview of key in vitro susceptibility testing methods and issues including disk diffusion testing and Etest (AB BIODISK, Solna, Sweden) method accuracy, interpretive criteria, and pharmacodynamic considerations for the selection of a breakpoint concentration are provided. The rapid bactericidal nature of the antibacterial activity of cefditoren, its post antibiotic effect, penicillin binding protein targets, and extent of beta-lactamase stability are all favorable qualities. In conclusion, this orally administered (BID) beta-lactam possesses promise for use against commonly isolated problematic respiratory tract pathogens such as penicillin-non-susceptible pneumococci and beta-lactamase-positive M. catarrhalis or H. influenzae. Success in the clinical trials will further define the role of cefditoren in this era of emerging resistant bacterial pathogens.