| Natural penicillin | Penicillin V | Streptococcus species and oral cavity anaerobes |
| Penicillinase-resistant penicillin | Cloxacillin (Tegopen) | Methicillin-sensitive Staphylococcus aureus and Streptococcus species |
| Dicloxacillin (Dynapen) |
| Nafcillin (Unipen)* |
| Oxacillin (Prostaphlin)* |
| Aminopenicillin | Amoxicillin | Same coverage as penicillin V, plus Listeria monocytogenes, Enterococcus species, Proteus mirabilis and some strains of Escherichia coli |
| Ampicillin |
| Bacampicillin (Spectrobid) |
| Beta-lactam–beta-lactamase inhibitor combination | Amoxicillin-clavulanate (Augmentin) | Same coverage as aminopenicillins, plus betalactamase–producing strains of methicillin-sensitive S. aureus, Haemophilus influenzae and Moraxella (formerly Branhamella) catarrhalis |
| Antipseudomonal penicillin | Carbenicillin (Geocillin) | Limited activity against Pseudomonas and Klebsiella species |
| First-generation cephalosporin | Cefadroxil (Duricef) | Improved coverage of methicillin-sensitive S. aureus, E. coli, P. mirabilis and Klebsiella species |
| Cephalexin (Keflex) |
| Cephradine (Velosef) |
| Second-generation cephalosporin | Cefaclor (Ceclor, Ceclor CD) | Compared with first-generation agents, better coverage of beta-lactamase–producing organisms |
| Cefprozil (Cefzil) | such as methicillin-sensitive S. aureus, H. influenzae, |
| Cefuroxime axetil (Ceftin) | M. catarrhalis, E. coli, P. mirabilis and Klebsiella species |
| Carbacephem | Loracarbef (Lorabid) | Same coverage as second-generation cephalosporins |
| Third-generation cephalosporin | Cefdinir (Omnicef) | Variable loss of Staphylococcus and Pneumococcus coverage; compared with second-generation cephalosporins, somewhat expanded coverage of gram-negative organisms; enhanced coverage of Proteus vulgaris and Providencia species |
| Cefixime (Suprax) |
| Cefpodoxime (Vantin) |
| Ceftibuten (Cedax) |