A compound of formula I for use as a medicament, wherein the use is in the treatment of a bacterial infection wherein formula I represents: wherein: Y represents: (i) (ii) -CF 3; (iii) -N(C 1-6 alkyl) 2; or (iv) C 3-6 cycloalkyl; N v, N w, N x, N y and N z independently represent -N= or -C = but wherein only a maximum of three of N v, N w, N x, N y and N z may represent -N=; n represents 0, 1 or 2; X 1 and X 2 independently represent -N- or -C -; when X 1 represents -N-, Q 1 represents a direct bond, -C - or -S 2 -; when X 1 represents -C -, Q 1 represents a direct bond or -N(R z)-; R z represents hydrogen or C 1-6 alkyl; R x represents C 1-6 alkyl (optionally substituted by one or more substituents selected from =O and A 1), aryl or heteroaryl (which latter two groups are each optionally substituted by one or more substituents selected from A 2 and A 3, respectively); R y, R y1 and R y2 independently represent hydrogen, halo, -CN, -OR 10, -N(R 11)(R 12) or C 1-6 alkyl (optionally substituted by one or more halo atoms); A 1, A 2, A 3 and A 4 independently represent halo, -CN, -OR 1, -S 0-2 C 1-3 alkyl, C 1-6 alkyl (optionally substituted by one or more halo substituents), heterocycloalkyl (optionally substituted by one or more substituents selected from C 1-3 alkyl and halo), aryl or heteroaryl (which latter two groups are optionally substituted by one or more substituents selected from B 1 and B 2, respectively); each R 1 and R 10 independently represent hydrogen, C 1-6 alkyl (optionally substituted by one or more halo substituents), aryl or heteroaryl (which latter two groups are optionally substituted by one or more substituents selected from halo, C 1-3 alkyl and -O-C 1-3 alkyl); R 11 and R 12 independently represent hydrogen or C 1-6 alkyl; B 1 and B 2 independently represent halo, - CN, C 1-6 alkyl (optionally substituted by one or more halo atoms), -OH or -O-C 1-6 alkyl (optionally substituted by one or more halo atoms), or a pharmaceutically acceptable salt thereof, with the proviso that the compound is not: Y represents: (i) (ii) -CF 3; (iii) -N(C 1-6 alkyl) 2; or (iv) C 3-6 cycloalkyl; (i) (ii) -CF 3; (iii) -N(C 1-6 alkyl) 2; or (iv) C 3-6 cycloalkyl; N v, N w, N x, N y and N z independently represent -N= or -C = but wherein only a maximum of three of N v, N w, N x, N y and N z may represent -N=; n represents 0, 1 or 2; X 1 and X 2 independently represent -N- or -C -; when X 1 represents -N-, Q 1 represents a direct bond, -C - or -S 2 -; when X 1 represents -C -, Q 1 represents a direct bond or -N(R z)-; R z represents hydrogen or C 1-6 alkyl; R x represents C 1-6 alkyl (optionally substituted by one or more substituents selected from =O and A 1), aryl or heteroaryl (which latter two groups are each optionally substituted by one or more substituents selected from A 2 and A 3, respectively); R y, R y1 and R y2 independently represent hydrogen, halo, -CN, -OR 10, -N(R 11)(R 12) or C 1-6 alkyl (optionally substituted by one or more halo atoms); A 1, A 2, A 3 and A 4 independently represent halo, -CN, -OR 1, -S 0-2 C 1-3 alkyl, C 1-6 alkyl (optionally substituted by one or more halo substituents), heterocycloalkyl (optionally substituted by one or more substituents selected from C 1-3 alkyl and halo), aryl or heteroaryl (which latter two groups are optionally substituted by one or more substituents selected from B 1 and B 2, respectively); each R 1 and R 10 independently represent hydrogen, C 1-6 alkyl (optionally substituted by one or more halo substituents), aryl or heteroaryl (which latter two groups are optionally substituted by one or more substituents selected from halo, C 1-3 alkyl and -O-C 1-3 alkyl); R 11 and R 12 independently represent hydrogen or C 1-6 alkyl; B 1 and B 2 independently represent halo, - CN, C 1-6 alkyl (optionally substituted by one or more halo atoms), -OH or -O-C 1-6 alkyl (optionally substituted by one or more halo atoms), or a pharmaceutically acceptable salt thereof, with the proviso that the compound is not: