aztreonam
Brand: Azactam
Prototype Drug
Drug Class: monobactam antibiotic
Drug Family: antibiotic
Subclass: gram-negative specific monobactam
Organ Systems: infectious-disease
Mechanism of Action
Selectively binds PBP3 of aerobic gram-negative bacteria, disrupting cell wall synthesis; the only commercially available monobactam with gram-negative-only spectrum. Does not bind gram-positive PBPs and has no anaerobic activity.
penicillin-binding protein 3 (PBP3) of gram-negative bacteria
Indications
- urinary tract infections (gram-negative)
- lower respiratory tract infections (gram-negative)
- septicemia
- skin/soft tissue infections (gram-negative)
- intra-abdominal infections (with anaerobic coverage)
- gynecological infections
- penicillin-allergic patients needing gram-negative coverage
Contraindications
- aztreonam hypersensitivity
Adverse Effects
Common
- injection site reactions
- elevated LFTs
- diarrhea
Serious
- C. difficile colitis
- anaphylaxis (rare — minimal cross-reactivity with other beta-lactams)
- hepatotoxicity
Pharmacokinetics (ADME)
| Absorption | IV or IM; IM absorption nearly complete (>90%) |
| Distribution | widely distributed; good penetration into peritoneal fluid, bile, bronchial secretions; CSF penetration poor unless meninges inflamed |
| Metabolism | minimal |
| Excretion | renal (60–70% unchanged) |
| Half-life | 1.7 hours |
| Onset | immediate (IV) |
| Peak | 1 hour (IM) |
| Duration | 8 hours |
| Protein Binding | 56% |
| Vd | moderate |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| aminoglycosides | synergistic gram-negative bactericidal activity; additive nephrotoxicity possible | moderate |
| ceftazidime-avibactam | combination used against metallo-beta-lactamase producers; aztreonam hydrolysis resisted by avibactam-protected ceftazidime | minor |
Nursing Considerations
- Aztreonam has minimal cross-reactivity with penicillins and cephalosporins, making it the preferred beta-lactam for documented IgE-mediated penicillin allergy requiring gram-negative coverage.
- Always combine with an anaerobic agent (metronidazole or clindamycin) when treating intra-abdominal or pelvic infections due to no anaerobic activity.
- Monitor renal function; dose reduction required when CrCl is <30 mL/min.
- Administer IV over 20–60 minutes or by slow IV push over 3–5 minutes.
Clinical Pearls
- Aztreonam shares a similar side chain with ceftazidime; patients with known IgE-mediated ceftazidime allergy may have cross-reactivity with aztreonam — ceftazidime allergy is one of the few situations where aztreonam should be used cautiously in 'penicillin-allergic' patients.
- Aztreonam-avibactam is an investigational combination for metallo-beta-lactamase producing pathogens (NDM) where ceftazidime-avibactam fails.
Safety Profile
Pregnancy generally-safe
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.
Gynecological Infections Intra-abdominal Infections (with Anaerobic Coverage) Lower Respiratory Tract Infections (gram-negative) Monobactam Antibiotic Penicillin-allergic Patients Needing Gram-negative Coverage Septicemia Skin/soft Tissue Infections (gram-negative) Urinary Tract Infections (gram-negative)