Examples of Beta-Lactam Antibiotics
Beta-lactam antibiotics include penicillins, cephalosporins, carbapenems, and monobactams—all sharing a common beta-lactam ring structure that inhibits bacterial cell wall synthesis.
Major Classes and Specific Examples
Penicillins
- Amoxicillin - commonly used for community-acquired infections 1
- Ampicillin - broad-spectrum penicillin 1
- Piperacillin (often combined with tazobactam) - extended-spectrum with antipseudomonal activity 1, 2
- Cloxacillin - penicillinase-resistant penicillin for staphylococcal infections 1
Cephalosporins
Organized by generation:
Second-generation:
Third-generation:
- Ceftazidime - strong antipseudomonal activity 1
- Ceftriaxone - long half-life, once-daily dosing 1
- Cefotaxime - broad gram-negative coverage 1
Fourth-generation:
- Cefepime - enhanced gram-negative and antipseudomonal coverage, though notably has higher neurotoxicity risk 1
Carbapenems
- Imipenem (with cilastatin) - very broad spectrum including anaerobes 1, 2
- Meropenem - similar to imipenem with lower seizure risk 1
- Ertapenem - once-daily carbapenem, lacks antipseudomonal activity 1, 3
Monobactams
- Aztreonam - unique in covering only gram-negative aerobes, safe in penicillin allergy 1
Novel Beta-Lactam Combinations
Recent additions include beta-lactam/beta-lactamase inhibitor combinations for multidrug-resistant organisms 4:
- Ceftolozane-tazobactam
- Ceftazidime-avibactam
- Meropenem-vaborbactam
- Imipenem-cilastatin-relebactam
- Cefiderocol (siderophore cephalosporin)
Important Clinical Distinctions
The guideline evidence 1 provides specific therapeutic drug monitoring targets for each beta-lactam, reflecting their different protein binding and pharmacokinetic properties. For example, ceftriaxone has only 10% free fraction while meropenem is nearly 100% free in plasma, significantly affecting dosing strategies.
Critical caveat: Cefazolin and cefepime have the highest pro-convulsive activity (294 and 160 times that of penicillin G, respectively), while cefoxitin has the lowest (1.8 times) 1. This becomes particularly important in patients with renal impairment or when high doses are used.