| abstract |
A compound of the formula: <IMAGE> wherein R1 is an amino group which may be protected, R3 is a hydrogen atom or an optionally substituted hydrocarbon residue; Z is S, S->O, O or CH2, R4 is a hydrogen atom, methoxy group or formamido group, R13 is a hydrogen atom, methyl group, hydroxyl group or halogen atom and A(+) is an optionally substituted imidazolium-1-yl group forming a condensed ring at the 2,3- or 3,4-position or a pharmaceutically acceptable salt or ester thereof is novel and has excellent antibacterial activity. |