A compound of formula for use in a method of treatment of a microbial infection in an animal which is optionally a human: wherein: Q is selected from Q1, Q2, Q3, Q4, Q5 and Q6: L is selected from -(CH 2) m -, -C(=O)-, -(CH 2) m -C(=O)-, -O-(CH 2) m - C(=O)-, -O-C(=O)-(CH 2) m -(C=O)-, -NH-C(=O)-, -NR-C(=O)-, -NH- (CH 2) m -C(=O)-, -NR-(CH 2) m -C(=O)-, -NH-C(=O)-(CH 2) m -C(=O)-, -NR-C(=O)-(CH 2) m -C(=O)-,-C(=O)-NH-(CH 2) m -C(=O)-, and -(CH 2) m -(CHR L)-C(=O)-, where m is an integer from 1 to 4; A 1 and A 2, together with the atoms to which they are bound, form an optionally substituted phenyl, naphthalene or heteroaryl group; R N is H; one of B 1, B 2, B 3, B 4, and B 5 is a group of formula -X-R x and the others are independently selected from H and R B; wherein each -R B is independently selected from halogen, -CF 3, -R, -OH, - OR, -OCF 3, -C(=O)OH, -C(=O)OR, -C(=O)R, -OC(=O)R, -NH 2, -NHR, -NR 2, -NO 2, - C(=O)NH 2, -C(=O)NHR, C(=O)NR 2, -S(=O)R, -S(=O) 2 R, -S(=O) 2 NR 2, or -CN; X is selected from a covalent bond or C 1-3 alkylene; R X is selected from -H, R XX or R XY; wherein: R XX is halogen, -CF 3, -OH, -OR, -OCF 3, -C(=O)OH, - NO 2, -NH 2, -NHR, -NR 2, -C(=O)NH 2, -C(=O)NR 2, -S(=O)R, -S(=O) 2 R, -S(=O) 2 NR 2, or -CN; and R XY is a group of formula -L X -R YY; wherein L X is selected from: -NH-C(=O)-O-, -NH-C(=O)-NH-, -NH-C(=O)- -O-C(=O)-NH-, -O-C(=O)-O-, -O-(C=O)- -C(=O)-NH-, -C(=O)-O-, -C(=O)-; and R YY is selected from C 1-4 alkyl, C 3-6 cycloalkyl, -C 6-14 aryl, -L Y -C 6 - 14 aryl, -L Y -O-C 6-14 aryl -C 5-6 heteroaryl, -L Y -C 5-6 heteroaryl, and -L Y -O-C 5-6 heteroaryl, wherein -L Y - is C 1-3 alkylene and wherein each of said groups is optionally substituted; R L is selected from halogen, -R LL, -CF 3, -OH, -OR LL, -NO 2, -NH 2, -NHR LL, -NR 2,-NH-C(=O)-R LL, -NH-C(=O)-O-R LL wherein R LL is selected from -C 1-4 alkyl,-C 3-6 cycloalkyl, -Ph, -L L -Ph, -C 5-6 heteroaryl, -L L -C 5-6 heteroaryl wherein -L L - is C 1-3 alkylene. and wherein each R is independently C 1-4 alkyl. Q is selected from Q1, Q2, Q3, Q4, Q5 and Q6: L is selected from -(CH 2) m -, -C(=O)-, -(CH 2) m -C(=O)-, -O-(CH 2) m - C(=O)-, -O-C(=O)-(CH 2) m -(C=O)-, -NH-C(=O)-, -NR-C(=O)-, -NH- (CH 2) m -C(=O)-, -NR-(CH 2) m -C(=O)-, -NH-C(=O)-(CH 2) m -C(=O)-, -NR-C(=O)-(CH 2) m -C(=O)-,-C(=O)-NH-(CH 2) m -C(=O)-, and -(CH 2) m -(CHR L)-C(=O)-, where m is an integer from 1 to 4; A 1 and A 2, together with the atoms to which they are bound, form an optionally substituted phenyl, naphthalene or heteroaryl group; R N is H; one of B 1, B 2, B 3, B 4, and B 5 is a group of formula -X-R x and the others are independently selected from H and R B; wherein each -R B is independently selected from halogen, -CF 3, -R, -OH, - OR, -OCF 3, -C(=O)OH, -C(=O)OR, -C(=O)R, -OC(=O)R, -NH 2, -NHR, -NR 2, -NO 2, - C(=O)NH 2, -C(=O)NHR, C(=O)NR 2, -S(=O)R, -S(=O) 2 R, -S(=O) 2 NR 2, or -CN; X is selected from a covalent bond or C 1-3 alkylene; R X is selected from -H, R XX or R XY; wherein: R XX is halogen, -CF 3, -OH, -OR, -OCF 3, -C(=O)OH, - NO 2, -NH 2, -NHR, -NR 2, -C(=O)NH 2, -C(=O)NR 2, -S(=O)R, -S(=O) 2 R, -S(=O) 2 NR 2, or -CN; and R XY is a group of formula -L X -R YY; R XX is halogen, -CF 3, -OH, -OR, -OCF 3, -C(=O)OH, - NO 2, -NH 2, -NHR, -NR 2, -C(=O)NH 2, -C(=O)NR 2, -S(=O)R, -S(=O) 2 R, -S(=O) 2 NR 2, or -CN; and R XY is a group of formula -L X -R YY; wherein L X is selected from: -NH-C(=O)-O-, -NH-C(=O)-NH-, -NH-C(=O)- -O-C(=O)-NH-, -O-C(=O)-O-, -O-(C=O)- -C(=O)-NH-, -C(=O)-O-, -C(=O)-; and R YY is selected from C 1-4 alkyl, C 3-6 cycloalkyl, -C 6-14 aryl, -L Y -C 6 - 14 aryl, -L Y -O-C 6-14 aryl -C 5-6 heteroaryl, -L Y -C 5-6 heteroaryl, and -L Y -O-C 5-6 heteroaryl, wherein -L Y - is C 1-3 alkylene and wherein each of said groups is optionally substituted; R L is selected from halogen, -R LL, -CF 3, -OH, -OR LL, -NO 2, -NH 2, -NHR LL, -NR 2,-NH-C(=O)-R LL, -NH-C(=O)-O-R LL wherein R LL is selected from -C 1-4 alkyl,-C 3-6 cycloalkyl, -Ph, -L L -Ph, -C 5-6 heteroaryl, -L L -C 5-6 heteroaryl wherein -L L - is C 1-3 alkylene. and wherein each R is independently C 1-4 alkyl. -NH-C(=O)-O-, -NH-C(=O)-NH-, -NH-C(=O)- -O-C(=O)-NH-, -O-C(=O)-O-, -O-(C=O)- -C(=O)-NH-, -C(=O)-O-, -C(=O)-; and R YY is selected from C 1-4 alkyl, C 3-6 cycloalkyl, -C 6-14 aryl, -L Y -C 6 - 14 aryl, -L Y -O-C 6-14 aryl -C 5-6 heteroaryl, -L Y -C 5-6 heteroaryl, and -L Y -O-C 5-6 heteroaryl, wherein -L Y - is C 1-3 alkylene and wherein each of said groups is optionally substituted; -O-C(=O)-NH-, -O-C(=O)-O-, -O-(C=O)- -C(=O)-NH-, -C(=O)-O-, -C(=O)-; and R YY is selected from C 1-4 alkyl, C 3-6 cycloalkyl, -C 6-14 aryl, -L Y -C 6 - 14 aryl, -L Y -O-C 6-14 aryl -C 5-6 heteroaryl, -L Y -C 5-6 heteroaryl, and -L Y -O-C 5-6 heteroaryl, wherein -L Y - is C 1-3 alkylene and wherein each of said groups is optionally substituted; R L is selected from halogen, -R LL, -CF 3, -OH, -OR LL, -NO 2, -NH 2, -NHR LL, -NR 2,-NH-C(=O)-R LL, -NH-C(=O)-O-R LL wherein R LL is selected from -C 1-4 alkyl,-C 3-6 cycloalkyl, -Ph, -L L -Ph, -C 5-6 heteroaryl, -L L -C 5-6 heteroaryl wherein -L L - is C 1-3 alkylene. and wherein each R is independently C 1-4 alkyl.