Quinolones used as MRS inhibitors and bactericides

A compound of formula (I):

• in which:
• R1 is optionally substituted aryl or optionally substituted heteroaryl;
• R2 is hydrogen, C(1-6)alkyl, arylC(1-4)alkyl, arylC(2-4)alkenyl or C(1-6)alkylcarbonyl;
• R3 is selected from halo, cyano, hydroxy, (C1-6)alkyl (optionally substituted by halo, hydroxy, amino, mono to perfluoro(C1-3)alkyl, carboxy or (C1-6)alkoxycarbonyl), (C3-7)cycloalkyl, C(1-6)alkoxy, amino, mono- or di-(C1-6)alkylamino, acylamino, carboxy, (C1-6)alkoxycarbonyl, carboxy(C1-6)alkyloxy, (C1-6)alkylthio, (C1-6)alkylsulphinyl, (C1-6)alkylsulphonyl, sulphamoyl, mono- and di-(C1-6)alkylsulphamoyl, carbamoyl, mono- and di-(C1-6)alkylcarbamoyl, and heterocyclyl;
• m is 0 or an integer from 1 to 3;
• X is CHR4 (wherein R4 is hydrogen, C(1-6)alkyl or aryl), C(2-4)alkylene, C(3-4)alkenylene or CO;
• Y is a linker group having from 2 to 6 methylene groups in a straight chain and in which one or more methylene groups may have one or more C(1-6) alkyl, C(1-6)alkoxy or C(1-6)alkylidenyl substituents and in which chain 1,2- or 1,3-carbon atoms may be linked by a C(2-3) alkylene or a C3 alkenylene bridge;
• R1 and X or R1 and R2 may be linked by a polymethylene chain to form a 5 to 7 membered ring, optionally substituted by C(1-6) alkyl;
• X and R2, X and Y or Y and R2 may be linked by a polymethylene chain to form a 4 to 7 membered ring, optionally substituted by C(1-6) alkyl;
• Z is NH or O;
• and
• salts thereof, preferably pharmaceutically acceptable salts thereof.