Oxazolidinone derivative having fused ring

An antimicrobial composition comprising a compound of the formula (I):

• or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, diluent or excipient;
• wherein:
• ring A is any one of the groups:
• in which the dashed line represents the presence or absence of a bond;
• m is 0 or 1;
• R is H, —NHC(═O)RA, —NHC(═S)RA, —NH-het1, —O-het1, —S-het1, —S(═O)-het1, —S(═O)2-het1, het2, —CONHRA, —OH, lower alkyl, lower alkoxy or lower alkenyl;
• RA is hydrogen, lower alkyl, halogenated lower alkyl, amino, (lower alkyl)amino, lower alkenyl, heterocycle (lower)alkyl, (lower alkyl)carbonyl, (lower alkyl)carbonyl lower alkyl, lower alkoxy, cycloalkyl, cycloalkyl(lower)alkyl, arylcarbonyl, arylcarbonyl(lower)alkyl, heterocyclecarbonyl or heterocyclecarbonyl(lower)alkyl;
• het1 and het2 are independently a heterocyclic group;
• ring B is a benzene ring optionally substituted;
• A1 and A2 are independently a nitrogen atom or a carbon atom;
• the dashed line represents the presence or absence of a bond;
• the fused ring C-D,
• is a fused ring of the formula (II-1-14) or the formula (II-2-14),
• R3 , R4 , R5 , and R7 are independently selected from Substituent Group A consisting of hydrogen, optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted lower alkoxy, carboxy, optionally substituted carbamoyl, cyano, formyl, optionally substituted (lower alkyl)carbonyl, optionally substituted (lower alkoxy)carbonyl, optionally substituted heterocyclic group, optionally substituted heterocyclecarbonyl, optionally substituted amino, optionally substituted aminocarbonyl, optionally substituted aryl, optionally substituted arylcarbonyl, (lower alkyl)sulfonyl, (lower alkyl)sulfinyl and halogen.