New research in macrolides and ketolides since 1997.

Macrolide and ketolide antibacterials remain a very dynamically active group. To overcome erythromycin A resistance within Gram-positive cocci and bacteria, novel compounds have been semi-synthesised, such as ketolides and C-4'' carbamate erythromycylamine derivatives. The continual efforts of those studying macrolides have led to molecular level investigations into the mechanism of action of these antibacterials. Among all novel derivatives, only telithromycin and AB-773 are currently under development. No real novel developments have been seen with the 15- and 16-membered ring macrolides, however, research is also continuing in this area. This review is an update of our knowledge in the field of macrolides.