Macrolides antibacterial activity against resistant

Compounds shown in Scheme 5 demonstrate antibacterial activity against many resistant organisms. Much of the benefit of this new class of macrolides... 

Allen reported in 1977 that naturally occurring 3-oxo (or 3-keto) macrolides such as pikromycin (81a) and narbomycin (81b) (Fig. 19) do not induce mac-rolide resistance in S. aureus, and they retained sufficient antibacterial activity [108]. On the other hand, derivatives of 3-decladinosyl-3-oxo-6-0-methyl EM (82) (Fig. 20) have been recently synthesized and designated as ketolides [109]. They generally exhibit significant activity against EM-resistant Gram-positive pathogens, and the features of their activity are fairly different from those of EM derivatives that bear cladinose at the C-3 position. 

ANTIBACTERIAL ACTIVITY CUndamycin resembles erythromycin in its in vitro activity against susceptible strains of pneumococci, S. pyogenes, and viridans streptococci. Ninety percent or more of strains of streptococci, including some that are macrolide-resistant, remain susceptible to... 

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