A compound represented by general formula (1) (wherein R1 represents a hydrogen atom, an optionally substituted C1-6 alkyl group or the like; R2 represents a hydrogen atom, an optionally substituted C1-6 alkyl group or the like; R3 represents a hydrogen atom or an optionally substituted C1-6 alkyl group; R4 represents a hydrogen atom, an optionally substituted C1-6 alkyl group or the like; X1 represents an optionally substituted C2-6 alkynylene group or the like; A represents an optionally substituted bivalent aromatic hydrocarbon group or the like; X2 represents an optionally substituted C1-6 alkylene group or the like; Y1 represents an oxygen atom or the like; and R5 represents a hydrogen atom or the like) or a salt thereof is useful as an antibacterial agent.