Ketolides

What are Ketolides?

Ketolides are a new generation of macrolide antibiotics designed to overcome issues with bacterial resistance to macrolides. They are semi-synthetic antibiotics derived from erythromycin (macrolide antibiotic) and the changes give ketolides a broader spectrum of activity.

Ketolides bind to the bacterial 50S ribosomal subunit and inhibit RNA-dependent protein synthesis. They are bacteriostatic at low concentrations and bactericidal at high concentration, so basically exhibit concentration dependent killing.

Ketolides have good antibacterial activity against Gram-positive bacteria such as those that cause respiratory tract infections.

The feature that distinguishes the ketolides from the macrolides is the presence of a 3-keto function in place of the L-cladinose moiety. This sugar residue had previously been thought to be essential for the antimicrobial activity of erythromycin.

Ketolides have a mechanism of action very similar to erythromycin A from which they have been derived. They potently inhibit protein synthesis by interacting close to the peptidyl transferase site of the bacterial 50S ribosomal subunit. Ketolides bind to ribosomes with higher affinity than macrolides.

Ketolides

Drug	Drug Description
Solithromycin	Investigated for the treatment of community-acquired pneumonia (CAP).
Telithromycin	An ketolide used to treat community acquired pneumonia of mild to moderate severity.

Ketolides bind to the bacterial 50S ribosomal subunit and inhibit RNA-dependent protein synthesis. They are bacteriostatic at low concentrations and bactericidal at high concentration, so basically exhibit concentration dependent killing.

Sulphonamides are an important class of antibiotic drugs with a wide range of activity, being very effective against gram-positive and certain gram-negative bacteria (White and Cooper 2003).