Aztreonam is a synthetic, bactericidal monobactam antibiotic with a narrow spectrum of activity primarily against aerobic Gram-negative bacilli. It is resistant to hydrolysis by most beta-lactamases, including extended-spectrum beta-lactamases (ESBLs), but is inactive against Gram-positive bacteria and anaerobes. It is a critical agent in the Indian context for treating serious Gram-negative infections, especially in hospital settings where resistance to other beta-lactams is prevalent.
Adult: Moderate to severe infections: 1 gm IV or IM every 8 to 12 hours. Severe or life-threatening infections (especially Pseudomonas): 2 gm IV every 6 to 8 hours. Maximum daily dose: 8 gm.
Note: IV: Reconstitute 1 gm vial with at least 3 mL of Sterile Water for Injection. Further dilute in 50-100 mL of compatible IV fluid (0.9% NaCl, D5W, LR). Infuse over 20-60 minutes. IM: Reconstitute 1 gm vial with at least 3 mL of Sterile Water for Injection or 0.9% NaCl. Inject deep into a large muscle mass (gluteus maximus, lateral thigh).
Aztreonam binds with high affinity to Penicillin-Binding Protein 3 (PBP-3) of susceptible Gram-negative aerobic bacteria. This binding inhibits the final transpeptidation step of peptidoglycan synthesis in the bacterial cell wall, leading to the formation of filamentous, non-viable cells and subsequent cell lysis and death.
Pregnancy: Pregnancy Category B. Animal studies have shown no risk, but no adequate and well-controlled studies in pregnant women. Use only if clearly needed.
Driving: Dizziness has been reported rarely. Patients should be cautioned about operating machinery or driving if they experience such effects.
| Probenecid | Competitively inhibits renal tubular secretion of aztreonam, increasing and prolonging serum levels. | Moderate |
| Furosemide and other Loop Diuretics | May increase the risk of nephrotoxicity and ototoxicity when combined with other aminoglycosides; relevance to aztreonam is less clear but caution advised. | Moderate |
| Cefoxitin, Imipenem | In vitro antagonism has been observed against some Gram-negative organisms; clinical significance is uncertain. | Low |
| Warfarin | Potential for increased anticoagulant effect; monitor INR closely. | Moderate |
| Alcohol (disulfiram-like reaction) | No disulfiram-like reaction reported with aztreonam. | None |