A compound represented by general formula (1) (wherein R
1
represents a hydrogen atom, an optionally substituted C
1-6
alkyl group or the like; R
2
represents a hydrogen atom, an optionally substituted C
1-6
alkyl group or the like; R
3
represents a hydrogen atom or an optionally substituted C
1-6
alkyl group; R
4
represents a hydrogen atom, an optionally substituted C
1-6
alkyl group or the like; X
1
represents an optionally substituted C
2-6
alkynylene group or the like; A represents an optionally substituted bivalent aromatic hydrocarbon group or the like; X
2
represents an optionally substituted C
1-6
alkylene group or the like; Y
1
represents an oxygen atom or the like; and R
5
represents a hydrogen atom or the like) or a salt thereof is useful as an antibacterial agent.