Monobactams are β-lactam compounds that contain an isolated β-lactam ring not fused to another ring, making them effective only against aerobic Gram-negative bacteria like Neisseria and Pseudomonas. Examples include aztreonam, tigemonam, nocardicin A, and tabtoxin. Potential adverse effects are skin rash, abnormal liver functions, and risk of seizures in susceptible individuals.

1. Monobactam
• Monobactams are β-lactam
compounds wherein the β-lactam
ring is alone and not fused to
another ring, in contrast to most
other β-lactams.
• They are effective only against
aerobic Gram-negative bacteria.
• (e.g., Neisseria, Pseudomonas).

2. Other examples of monobactams are
•aztreonam.
•tigemonam,
•nocardicin A,
•and tabtoxin.

3. Aztreonam. (The four-membered ring at the bottom
is the β-lactam. There is a second thiazole ring, but it
is not fused to the β-lactam ring.)

4. Tigemonam

5. Adverse effects to monobactams
can include
• skin rash
• and occasional abnormal liver
functions.
• They have no cross-hypersensitivity
reactions with penicillin but like
penicillins can trigger seizures in
patients with history of seizures.