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 β-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 anerobic and anaerobic Gram-positive cocci. The level of cefditoren activity against S. pneumoniae (MIC 90, 0.5 μg/mL) was superior to all marketed oral cephalosporins and at least equal to amoxicillin ± clavulanate. H. influenzae (MIC 90, 0.016–0.03 μg/mL) and M. catarrhalis (MIC 90, 0.06–0.5 μg/mL) were also very susceptible to cefditoren. In contrast to cefixime and ceftibuten, cefditoren was active against oxacillin-susceptible staphylococci (MIC 90, ≤ 1 μg/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, β-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 β-lactamase stability are all favorable qualities. In conclusion, this orally administered (BID) β-lactam possesses promise for use against commonly isolated problematic respiratory tract pathogens such as penicillin-non-susceptible pneumococci and β-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.