Examples of Beta-Lactam Antibiotics
Beta-lactam antibiotics comprise five major structural classes: penicillins, cephalosporins, carbapenems, monobactams, and penems 1, 2.
Major Classes and Specific Examples
Penicillins
- Natural penicillins: Penicillin G
- Aminopenicillins: Amoxicillin, Ampicillin
- Penicillinase-resistant penicillins: Cloxacillin, Flucloxacillin
- Extended-spectrum penicillins: Piperacillin (often combined with tazobactam)
- Penicillin/beta-lactamase inhibitor combinations: Ampicillin/sulbactam, Amoxicillin/clavulanate, Piperacillin/tazobactam 1, 3, 2
Cephalosporins
Organized by generation:
- First generation: Cefazolin
- Second generation: Cefoxitin, Cefotetan
- Third generation: Cefotaxime, Ceftriaxone, Ceftazidime
- Fourth generation: Cefepime
- Fifth generation: Ceftolozane (combined with tazobactam), Cefditoren 4, 3, 2
Carbapenems
Monobactams
Novel Beta-Lactam Combinations
Recent additions include:
- Ceftazidime-avibactam
- Meropenem-vaborbactam
- Cefiderocol 5
Key Structural Characteristic
All beta-lactam antibiotics share a common four-membered beta-lactam ring structure, which is essential for their mechanism of action—inhibiting bacterial cell wall synthesis by binding to penicillin-binding proteins 1, 6. The different classes vary in their side chains and additional ring structures attached to this core beta-lactam ring, which determines their spectrum of activity, stability to beta-lactamases, and pharmacokinetic properties 1.
Clinical Context
The choice among these agents depends on the suspected or confirmed pathogen, local resistance patterns, site of infection, and patient-specific factors 4. For example, carbapenems like meropenem and imipenem have the broadest spectrum and are typically reserved for serious infections or resistant organisms, while specific cephalosporins or penicillins may be appropriate for community-acquired infections 3.