Cefetamet pivoxil: comparable evaluation with other orally available antibiotics against selected species of respiratory pathogens.

Cefetamet pivoxil, the prodrug ester of cefetamet, is a new third-generation cephalosporin with a broad spectrum of activity. The in vitro activity of cefetamet was superior to that of cefaclor, ceftibuten, amoxicillin plus clavulanic acid, and amoxicillin alone when tested against 403 strains of freshly isolated upper and lower respiratory tract pathogens. Cefetamet killed 100% Haemophilus influenzae and H. parainfluenzae, including beta-lactamase-producing strains, at < or = 0.25 mg/l, Streptococcus pyogenes and S. pneumoniae at < or = 0.5 mg/l, S. agalactiae at < or = 0.1 mg/l, and streptococci at < or = 2.0 mg/l. Moreover, at < or = 4 mg/l (breaking point), cefetamet was also highly effective against Escherichia coli (94%), Klebsiella pneumoniae (92%), K. oxytoca (91%) and, at 1 mg/l, against Moraxella catarrhalis (90%), including beta-lactamase-producing strains. Furthermore, time-killing analyses at 4 x MIC demonstrated that cefetamet was bactericidal against beta-lactamase-producing H. influenzae, M. catarrhalis, and K. pneumoniae within 6 h and S. pneumoniae within 4 h. Hydrolysis studies confirmed cefetamet's stability to TEM1 and SHV1, the most common enterobacterial beta-lactamases.