Antimicrobial
Monobactams (aztreonam)
Monocyclic beta-lactam, Gram-negative only
MON-oh-bak-tams
High-yield clue
Aztreonam binds PBP3 of aerobic Gram-negative rods only and is the beta-lactam considered safe in most penicillin allergy vocabulary.
Overview
A monocyclic beta-lactam class represented by aztreonam, studied as the beta-lactam with activity limited to aerobic Gram-negative rods and with minimal cross-reactivity in penicillin allergy.
Classification
- Beta-lactam (monocyclic)
- Bactericidal
- Binds penicillin-binding protein 3 (PBP3)
- Aerobic Gram-negative spectrum
Lab & identification clues
- No meaningful Gram-positive or anaerobe activity concept
- Low immunologic cross-reactivity with penicillins
- Susceptible to some ESBLs / carbapenemase-producing organisms
Associations
- Aerobic Gram-negative rod coverage vocabulary
- Penicillin-allergy alternative concept
- Synthetic monobactam origin (Chromobacterium-derived scaffold)
Commonly confused with
- Carbapenems
- Cephalosporins
Your notes
Original mechanism summary for microbiology study. Sources checked: CDC antimicrobial-resistance guidance, NCBI Bookshelf Medical Microbiology, and standard coursework frameworks; reviewed 2026-06. Covers class, mechanism, and resistance vocabulary only; no prescribing, dosing, or patient-specific treatment guidance.