Aztreonam

Aztreonam (trade name Azactam) is a synthetic monocyclic beta-lactam antibiotic (a monobactam) originally isolated from Chromobacterium violaceum. It was approved by the FDA in 1986. It is resistant to some beta-lactamases, but is inactivated by extended-spectrum beta-lactamases.

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Mechanism of action

Aztreonam is similar in action to penicillin. It inhibits mucopeptide synthesis in the bacterial cell wall. It has a very high affinity for penicillin-binding protein 3 (PBP-3) and mild affinity for PBP-1a. Aztreonam binds the penicillin-binding proteins of gram-positive and anaerobic bacteria very poorly and is largely ineffective against them.^[1] Aztreonam is bactericidal but less so than some of the cephalosporins.

Indications

Aztreonam has strong activity against susceptible gram-negative bacteria, including Pseudomonas aeruginosa. It has no useful activity against gram-positive bacteria or anaerobes. It is known to be effective against a wide range of bacteria including Citrobacter, Enterobacter, E coli, Haemophilus, Klebsiella, Proteus, and Serratia species.^[2]

Administration

Aztreonam must be administered intravenously, as the compound is poorly absorbed when given via the oral route. Phase III trials are currently in progress to measure its delivery in inhaled form, using an ultrasonic nebulizer.

Common adverse effects

Reported side-effects include injection site reactions, rash, and rarely toxic epidermal necrolysis. Gastrointestinal side effects generally include diarrhea and nausea and vomiting. There may be drug-induced eosinophilia. There is limited cross-reactivity between aztreonam and other beta-lactam antibiotics, and it is generally considered safe to admininister aztreonam to patients with hypersensitivity (allergies) to penicillins.^[1]

Aztreonam is considered Pregnancy category B.

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