Cephalexin is a prescription antibiotic that kills bacteria by inhibiting bacterial cell wall synthesis. This active ingredient has been proven effective against Staphylococcus aureus, including penicillinase-producing strains resistant to Penicillin or Amoxicillin, as well as certain strains of Escherichia coli, Proteus mirabilis, Shigella, Klebsiella spp., and others.