Cephalosporin Antibiotics: Complete Classification
Cephalosporins are a large class of beta-lactam antibiotics organized into generations (first through fourth), with each generation having distinct antimicrobial coverage patterns. 1
First-Generation Cephalosporins
- Cefazolin (IV/IM)
- Cefalexin/Cephalexin (oral)
- Cefadroxil (oral)
- Cephalothin (IV/IM)
- Cephaloridine (oral)
These agents maintain excellent activity against streptococci and staphylococci but have limited gram-negative coverage 1, 2, 3.
Second-Generation Cephalosporins
- Cefuroxime (IV/IM and oral)
- Cefoxitin (IV/IM)
- Cefaclor (oral)
- Cefprozil (oral)
Second-generation agents have a wider spectrum of efficiency compared to first-generation drugs 1, 4.
Third-Generation Cephalosporins
- Ceftriaxone (IV/IM)
- Cefotaxime (IV/IM)
- Ceftazidime (IV/IM) - provides antipseudomonal coverage
- Cefoperazone (IV/IM) - provides antipseudomonal coverage
- Ceftizoxime (IV/IM)
- Cefepime (IV/IM) - sometimes classified as fourth-generation
- Cefixime (oral)
- Cefpodoxime proxetil (oral)
- Ceftibuten (oral)
Third-generation cephalosporins have expanded gram-negative coverage, with ceftazidime and cefoperazone being the only third-generation drugs providing antipseudomonal activity 1, 2, 5. Cefotaxime and ceftizoxime maintain the best gram-positive coverage among third-generation agents 5. Most third-generation cephalosporins (except cefoperazone) penetrate cerebrospinal fluid and are indicated for bacterial meningitis 5.
Fourth-Generation Cephalosporins
- Cefepime (IV/IM)
- Cefpirome (IV/IM)
Cefepime provides excellent activity against both gram-positive and gram-negative pathogens, including antibiotic-resistant Enterobacteriaceae 6, 2.
Newer Beta-Lactam/Beta-Lactamase Inhibitor Combinations
While not pure cephalosporins, these combinations include cephalosporin components:
Key Clinical Distinctions
Important caveat: No cephalosporin is active against enterococci, and none should be used as monotherapy for suspected enterococcal infections 3. Additionally, loracarbef, while often grouped with cephalosporins, is technically a carbacephem with a similar structure 7.
The selection of a specific cephalosporin depends on the infection site, suspected pathogens, local resistance patterns, and whether gram-positive, gram-negative, or antipseudomonal coverage is required 1, 2.