Aztreonam
Azactam
Monobactam β-lactam (gram-negative only)
Monobactam that inhibits gram-negative PBP3. No gram-positive or anaerobic activity.
Indications
- •Gram-negative infections in patients with SEVERE penicillin/cephalosporin allergy (safe alternative)
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Typical | 1–2 g IV q8h | — |
Pharmacokinetics
Half-life ~1.7 h. Renally cleared.
Side effects
- !Generally well tolerated
- !C. difficile
Contraindications
- ×Ceftazidime allergy (SHARED side-chain — the one cross-reactivity)
Clinical pearls
- ★Safe in penicillin/cephalosporin anaphylaxis — the go-to β-lactam for gram-negatives in β-lactam-allergic patients.
- ★EXCEPTION: shares a side-chain with ceftazidime → avoid if ceftazidime allergy.
Other drugs in Antibiotics
- Cefazolin
β-lactam — inhibits bacterial cell wall PBPs.
- Vancomycin
Inhibits cell wall synthesis (binds D-Ala-D-Ala). Active against MRSA + gram-positives.
- Clindamycin
Binds 50S ribosomal subunit, blocks peptide-bond formation. Bacteriostatic against most organisms; bactericidal against susceptible streptococci. Excellent activity against anaerobes and gram-positive cocci including community-acquired MRSA.
- Gentamicin
Binds 30S ribosomal subunit, causes misreading of mRNA → defective bacterial protein synthesis. Bactericidal, concentration-dependent killing. Synergy with cell-wall agents (β-lactams, vancomycin) for gram-positive endocarditis.
- Cefuroxime
β-lactam — inhibits cell-wall synthesis (PBP binding). 2nd-gen: gram-positive + expanded gram-negative.
- Cefepime
β-lactam cell-wall inhibitor. Broad gram-negative (incl. Pseudomonas) + gram-positive coverage.
- Cefotetan
β-lactam; adds anaerobic (B. fragilis) coverage → colorectal/gynecologic prophylaxis.
- Cefotaxime
β-lactam cell-wall inhibitor. Broad gram-negative + CNS penetration.
Browse all classes: /reference/drugs
Suggested reading
- •Miller's Anesthesia, 9e
- •FDA package insert
