4"-Epi erythromycin A and derivatives thereof as useful antibacterial agents

A compound selected from the group consisting of a macrolide antibiotic of the formula:

• ##STR4## and the pharmaceutically acceptable acid addition salts thereof, wherein R is selected from the group consisting of hydrogen, alkanoyl having from two to three carbon atoms and ethyl succinyl;
• R.sub.1 and R.sub.2 when considered separately are, respectively, hydroxy and hydrogen;
• R.sub.1 and R.sub.2 when considered together are an oxo group;
• R.sub.3 and R.sub.4 when considered separately are each hydrogen;
• and R.sub.3 and R.sub.4 when considered together are >C.dbd.O.