Monobactams

Monobactams are beta-lactam antibiotics with a distinct monocyclic beta-lactam ring that provides effectiveness against beta-lactam producing bacteria.  Monobactams have the same mechanism as other beta-lactams.  Monobactams are cell wall inhibitors and work primarily by inhibition of transpeptidation of the cell wall, which decreases the cell wall strength and integrity.  Monobactams also work on penicillin binding proteins to weaken the wall structure and also by promotion of autolysins.  Monobactams are not effective against extended spectrum beta-lactamases (ESBL).  

Class Drugs

• Aztreonam

Class Mechanism of Action

Three mechanisms of action:

• Cell wall inhibitor

Inhibits transpeptidation, which decreases cell wall strength/integrity

• Only effective against rapidly growing bacteria

• Inactivation of penicillin binding proteins (PBPs)

Bacteria have proteins on the surface that bind to cephalosporin, resulting in morphologic changes to the bacteria and weakening the structure of the cell wall

• Certain bacteria can develop resistance to cephalosporins by altering their surface proteins to decrease interaction of drug with bacteria

• Autolysins

Many bacteria naturally produce autolysins that usually assist in performing "maintenance" function for the bacteria by degrading the cell wall.  If new cell wall is not being produced in the presence of a carbapenem, the autolysins aid in destruction of the cell wall.

Class Applications

Treatment of gram negative infections

Class Adverse Effects

Resistance

• Beta-lactamase

Not effective against ESBL (extended spectrum beta-lactamase)

• Resistant to most beta-lactamases

Hypersensitivity - less likely than other beta-lactams

Diarrhea

• Alteration of normal gut flora causes diarrhea

• Clostridium difficile can also cause a severe form of diarrhea with use of antibiotics

Drug Table

Drug Name	Application	Comments	Image
Aztreonam			"Aztec" "Tree" "'Nam"