Cefriaxone group
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ceftriaxone drug class third-generation cephalosporin FDA label
Ceftriaxone group: a third-generation cephalosporin antibiotic.
It is a beta-lactam drug that inhibits bacterial cell-wall synthesis by binding penicillin-binding proteins.
Key point: it is usually given IV or IM and has broad activity against many Gram-negative organisms, though it does not reliably cover Pseudomonas aeruginosa.
Create a quick reference table for cephalosporin generations
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cephalosporin generations examples spectrum antimicrobial stewardship official guidance
| Generation | Common examples | Typical spectrum / key point | Common clinical uses |
|---|---|---|---|
| 1st | Cefazolin, cephalexin, cefadroxil | Stronger Gram-positive coverage, including MSSA and streptococci. Limited Gram-negative activity: PEcK (Proteus mirabilis, E. coli, Klebsiella pneumoniae). | Surgical prophylaxis (cefazolin), uncomplicated skin and soft-tissue infection, selected UTIs |
| 2nd | Cefuroxime, cefaclor, cefprozil | More Gram-negative activity than 1st generation; retains moderate Gram-positive coverage. | Respiratory infections, otitis/sinusitis, some UTIs |
| 2nd, cephamycins | Cefoxitin, cefotetan | Useful anaerobic activity, including Bacteroides fragilis. | Intra-abdominal or pelvic infection; colorectal surgical prophylaxis |
| 3rd | Ceftriaxone, cefotaxime, cefixime, cefpodoxime, ceftazidime | Broad Gram-negative coverage and good streptococcal activity. Ceftriaxone/cefotaxime penetrate CSF. Ceftazidime covers Pseudomonas. | Meningitis, gonorrhea, community-acquired pneumonia, severe infections; ceftazidime for susceptible Pseudomonas |
| 4th | Cefepime | Broad Gram-positive and Gram-negative coverage; stable against many beta-lactamases. Covers Pseudomonas. | Serious hospital-acquired infections, febrile neutropenia, suspected Pseudomonas infection |
| 5th | Ceftaroline | Adds activity against MRSA via binding altered PBP2a. Does not cover Pseudomonas. | MRSA skin/soft-tissue infection and community-acquired pneumonia |
High-yield reminders
- All cephalosporins are beta-lactam, bactericidal antibiotics that inhibit bacterial cell-wall synthesis.
- They do not reliably cover Enterococcus, Listeria, or atypical organisms.
- MRSA: generally resistant, except ceftaroline.
- Pseudomonas: remember ceftazidime and cefepime.
- Increasing generation usually means more Gram-negative activity, but this is a useful rule rather than an absolute rule. The textbook describes first-generation agents as more Gram-positive active, with third/fourth generations having broader Gram-negative activity. Dermatology 2-Volume Set 5e, mechanism of action section; NCBI cephalosporin overview.
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