Cephem compounds, their production and use

A compound of formula (I) or a pharmaceutically acceptable salt thereof:

• wherein in the formula (I),
• (i) A is define by the formula (Ia):
• Where where X is N, C(H), C(F) or C(Cl);
• (ii) B is defined as hydrogen, methyl, ethyl or represented by the formula (Ib)
• wherein, R1 and R2 is independently hydrogen or lower alkyl;
• or
• wherein R1 and R2 together may form a 3 to 6-membered spiro ring system;
• and
• m is 0 or 1;
• (iii) C represents a quaternized bicyclic nitrogen containing aromatic heterocyclic ring represented by the formulae (Ic) to (Iz)
• (iv) D represents CH2, CH2CH2 or CH2CO;
• (v) E represents a substituted or unsubstituted benzene ring or a substituted or unsubstituted 5- or 6-membered aromatic heterocyclic ring having at least one heteroatom selected from the group consisting of O, S and N, wherein the heteroaromatic ring includes is pyrrolyl, imidazolyl, pyrazolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazolyl, isoxazolyl, oxazolyl, oxadiazolyl, isothiazolyl, thiazolyl, thiadiazolyl, furyl, and or thienyl;
• (vi) F is optionally substituted amidine or optionally substituted guanidine;
• and
• (vii) G is hydrogen, methyl, ethyl, C3-6 alkyl, C3-6 cycloalkyl or a an optionally substituted 5- or 6-membered aliphatic or a an optionally substituted 5- or 6-membered aromatic heterocyclic ring, wherein the heterocyclic ring is substituted with at least 1-2 hetero atoms selected from the group consisting of N, O, and S (αor β α or β).