Cefprozil is an orally bioavailable, second generation, broad-spectrum cephalosporin antibiotic that inhibits the growth of both Gram-positive and Gram-negative bacteria. It inhibits the growth of E. coli, E. faecalis, E. faecium, N. gonorrhoeae, N. meningitidis, P. mirabilis, S. aureus, S. pyogenes, and S. pneumoniae strains (MICs = 0.013-25 μg/ml) and clinical isolates of penicillin-susceptible, -intermediate, and -resistant S. pneumoniae and methicillin-sensitive S. aureus (MICs = 0.12-16 μg/ml). In vivo, cefprozil protects mice challenged with E. coli, S. aureus, S. pyogenes, and P. mirabilis strains with protective doses (PDs) ranging from 0.07 to 1.3 mg/kg. Cefprozil binds to penicillin-binding proteins (PBPs), which disrupts their ability to cross-link peptidoglycan and leads to weakened bacterial cell walls. Formulations containing cefprozil have been used in the treatment of respiratory tract, skin, and other bacterial infections.