Master Aztreonam with Picmonic for Medicine

Monobactams differ from the other beta-lactam antibiotics by having a standalone beta-lactam ring with a special affinity for penicillin-binding protein 3 (PBP3).

As a monobactam antibiotic, aztreonam is resistant to beta-lactamases but may still be susceptible to extended-spectrum beta-lactamases.

Aztreonam has a special affinity for penicillin-binding protein 3. Gram-positive bacteria and anaerobes have different penicillin-binding proteins that aztreonam does not bind well.

By binding tightly to PBP3, aztreonam disrupts cell wall synthesis, which leads to cell lysis and death. Its affinity for PBP3 is key to its bactericidal effect in gram-negative bacteria.

Aztreonam is a bactericidal antibiotic. It inhibits cell wall synthesis by binding specifically to penicillin-binding protein 3 (PBP-3) in Gram-negative bacteria, weakening the bacterial cell wall. The disruption of the cell wall's integrity causes bacterial cell lysis and death.

In clinical use, aztreonam is limited to Gram-negative bacteria because it has no useful activity against Gram-positives. It also has no activity against anaerobes and can only be used for aerobic organisms.

Aztreonam has strong activity against susceptible Gram-negative bacteria, especially Gram-negative bacilli, including Pseudomonas, Enterobacter, E. coli, Haemophilus, Klebsiella, and Proteus.

Aztreonam is commonly used to treat cystic fibrosis exacerbations, as Pseudomonas aeruginosa is one of the most common pathogens involved. It is typically administered IV or IM, but a nebulized form is available for respiratory infections.

Aztreonam is structurally different enough from penicillin that there is no cross-reactivity to individuals with penicillin allergies. Therefore, this antibiotic is often used in patients who have penicillin allergies.

Many studies demonstrate synergism between aztreonam and aminoglycoside antibiotics like gentamicin and tobramycin. The combination is particularly effective against Pseudomonas aeruginosa. Aztreonam disrupts cell wall synthesis, making it easier for aminoglycosides to enter bacterial cells and inhibit protein synthesis.

Aztreonam causes mild to moderate digestive disturbances. Symptoms can include nausea, vomiting, diarrhea, and abdominal pain. These symptoms are generally self-limiting and not severe, though they can impact patient comfort and adherence to the medication.

Patients may experience pain at the injection site. Thrombophlebitis, an inflammation of the vein due to a blood clot (thrombus), may also occur. This side effect can cause pain, swelling, warmth, and redness around the affected vein.