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Monobactam antibiotic

Aztreonam

Brand names: Azactam, Cayston

Aztreonam is a monobactam antibiotic active against aerobic Gram-negative bacteria, including Pseudomonas aeruginosa, and is also available in an inhaled form for cystic fibrosis.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It binds penicillin-binding protein 3 in Gram-negative bacteria, inhibiting cell wall synthesis and causing bacterial death.

Prescribing in practice

  • It has a low rate of cross-reactivity with other beta-lactams, making it a useful option in many penicillin-allergic patients, though caution is advised with ceftazidime allergy due to a shared side chain.
  • It has no useful activity against Gram-positive bacteria or anaerobes, so additional cover is needed for mixed infections.
  • The inhaled formulation is used to manage chronic Pseudomonas infection in cystic fibrosis.

Monitoring

Monitor clinical response and, with prolonged therapy, renal and hepatic function and full blood count.

Counselling the patient

  • Report any rash, swelling or breathing difficulty.
  • With the inhaled form, use a bronchodilator beforehand if advised and follow the prescribed inhalation technique.
  • Complete the full course as directed.

Evidence & guidelines

Aztreonam is an established option for Gram-negative infections, and inhaled aztreonam is supported for chronic Pseudomonas infection in cystic fibrosis.

Reference: BSAC; CF Trust; UKHSA AMR; SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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