A compound represented by the formula: or a pharmaceutically acceptable salt thereof, wherein, R 2 is a substituted or unsubstituted, branched or unbranched C 10 -C 25 aliphatic moiety; R 9 is -C OH; L is a bivalent, branched or unbranched, saturated or unsaturated, C 2 -C 6 hydrocarbon chain wherein one or more methylene units of L is independently replaced by -O-, -S-, -NH-, -C -, -CF 2 -, -C(=CH 2)-, -CH=CH-, or an optionally substituted arylene, heteroarylene, C 3 -C 6 cycloalkylene, C 3 -C 6 heterocycloalkylene, or an 8-10-membered bicyclic heterocyclic moiety, and wherein L is optionally substituted by one or more groups selected from halogen, C 1 -C 6 alkyl, phenyl, biphenyl, -benzyl, -CH 2 -phenol, -CH(phenyl) 2, -OH, -NH 2, - NHC CH 3, -NHC NHCH 2 CH 3, -C NH 2, -C NHCH 2 CH 3, - CH 2 C OCH 2 phenyl, -(CH 2) 2 SCH 3, -(CH 2) 2 C NH 2, -(CH 2) 2 C OH, an 8-10 membered bicyclic aryl ring, a 5-6 membered heteroaryl ring having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, an 8-10 membered bicyclic heteroaryl ring having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, a 5- to 7-membered monocyclic having 1-2 heteroatoms independently selected from nitrogen, oxygen, or sulfur or a 7-10 membered bicyclic heterocyclyl ring having 1-2 heteroatoms independently selected from nitrogen, oxygen, or sulfur; M is -C -, -C -, or -SO 2 -; R 10 is hydrogen, F, CF 3, C 1 -C 4 alkyl, -OH, -C CH 3, -NH(OR E), -NR E 2, -NHNR E 2, - SO 2 R E, -NH-phenyl, -SO 2 -phenyl, -phenyl-NO 2, or -OR E, wherein each R E is independently hydrogen, oxygen, or a substituted or unsubstituted group selected from C 1-6 aliphatic or C 1-6 heteroaliphatic; Y is -S-; for use as an antibacterial agent in the prevention and/or treatment of an epithelial condition caused or aggravated by bacteria in animals. R 2 is a substituted or unsubstituted, branched or unbranched C 10 -C 25 aliphatic moiety; R 9 is -C OH; L is a bivalent, branched or unbranched, saturated or unsaturated, C 2 -C 6 hydrocarbon chain wherein one or more methylene units of L is independently replaced by -O-, -S-, -NH-, -C -, -CF 2 -, -C(=CH 2)-, -CH=CH-, or an optionally substituted arylene, heteroarylene, C 3 -C 6 cycloalkylene, C 3 -C 6 heterocycloalkylene, or an 8-10-membered bicyclic heterocyclic moiety, and wherein L is optionally substituted by one or more groups selected from halogen, C 1 -C 6 alkyl, phenyl, biphenyl, -benzyl, -CH 2 -phenol, -CH(phenyl) 2, -OH, -NH 2, - NHC CH 3, -NHC NHCH 2 CH 3, -C NH 2, -C NHCH 2 CH 3, - CH 2 C OCH 2 phenyl, -(CH 2) 2 SCH 3, -(CH 2) 2 C NH 2, -(CH 2) 2 C OH, an 8-10 membered bicyclic aryl ring, a 5-6 membered heteroaryl ring having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, an 8-10 membered bicyclic heteroaryl ring having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, a 5- to 7-membered monocyclic having 1-2 heteroatoms independently selected from nitrogen, oxygen, or sulfur or a 7-10 membered bicyclic heterocyclyl ring having 1-2 heteroatoms independently selected from nitrogen, oxygen, or sulfur; M is -C -, -C -, or -SO 2 -; R 10 is hydrogen, F, CF 3, C 1 -C 4 alkyl, -OH, -C CH 3, -NH(OR E), -NR E 2, -NHNR E 2, - SO 2 R E, -NH-phenyl, -SO 2 -phenyl, -phenyl-NO 2, or -OR E, wherein each R E is independently hydrogen, oxygen, or a substituted or unsubstituted group selected from C 1-6 aliphatic or C 1-6 heteroaliphatic; Y is -S-; for use as an antibacterial agent in the prevention and/or treatment of an epithelial condition caused or aggravated by bacteria in animals.