| abstract |
A rifamycin derivative having the formula (I): ##STR1## wherein R 1 is hydrogen atom, methyl group or ethyl group, R 2 is an alkyl group having 1 to 4 carbon atoms, and A is a group having the formula: ##STR2## in which n is an integer of 3 to 5, or group having the formula: ##STR3## in which R 3 is a alkyl group having 1 to 5 carbon atoms; or a salt thereof. The rifamycin derivative (I) exhibits a strong antibacterial activity against Gram-positive bacteria and acid-fast bacteria, and also exhibits a strong antibacterial activity against tubercle bacilli. |