Compounds of formula (I) have antibacterial activity: wherein: m is 0 or 1； Q is hydrogen or cyclopropyl； AIk is an optionally substituted, divalent C1-C6 alkylene, alkenylene or alkynylene radical which may contain an ether (&mdash；O&mdash；), thioether (&mdash；S&mdash；) or amino (&mdash；NR)&mdash； link, wherein R is hydrogen, &mdash；CN or C1-C3 alkyl； X is &mdash；C(&boxH；O)NR6&mdash；, &mdash；S(O)NR6&mdash；, &mdash；C(&boxH；O)O&mdash； or &mdash；S(&boxH；O)O&mdash； wherein R6 is hydrogen, optionally substituted C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, -Cyc, or &mdash；(C1-C3 alkyl)-Cyc wherein Cyc is optionally substituted monocyclic carbocyclic or heterocyclic having 3-7 ring atoms； Z is N or CH, or CF； R2 and R3 are as defined in the description.
