Imidazo[4,5-b]-pyridinium-containing cephem compounds having broad antibacterial spectrum activity

A compound of the formula(I):

• 91
• wherein,
• X is N or CY and Y is H or halogen;
• R1 is amino or protected amino;
• R2 is hydrogen, optionally substituted lower alkyl or optionally substituted cycloalkyl;
• R3 is hydrogen, hydroxy, halogen, optionally substituted lower alkyl, optionally substituted lower alkoxy, optionally substituted lower alkylthio or optionally substituted amino;
• R4 is hydrogen, hydroxy, optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted lower alkoxy, optionally substituted cycloalkyl, optionally substituted cycloalkyl(lower)alkyl or an optionally substituted N-containing heterocyclic group;
• R5 is hydrogen, amino, optionally substituted lower alkyl, optionally substituted lower alkoxy or optionally substituted lower alkylthio, or R4 and R5 taken together may form lower alkylene in which an optional hetero atom(s) intervene;
• and
• a wavy line means syn- or anti-isomerism or a mixture thereof, an ester, a pharmaceutically acceptable salt, a prodrug, or a solvate thereof.