This invention relates to compounds having the formula: ##STR1## in which: R represents a C.sub.1-6 alkyl radical or a C.sub.1-6 alkenyl radical; A represents an indazol-2,3- or 4,5- or 6,7-diyl radical, which indazoldiyl radical may be substituted on the nitrogen atoms at 1- or 2-position with C.sub.1-6 alkyl or phenyl-(C.sub.1-6) alkyl radicals, and their salts with pharmaceutically acceptable bases.Said compounds are therapeutically useful as antibacterial agents.