Cephem compound having pyridinium group

A compound of the formula:

• or an amino-protected compound when the amino group is present on the ring in the 7-side chain, or a pharmaceutically acceptable salt thereof, wherein
• W is —CH2;
• U is —S—, —S(═O)— or —O—;
• L is a single bond, an optionally substituted lower alkylene group, an optionally substituted lower alkenylene group or an optionally substituted alkynylene group;
• R1 is an optionally substituted carbocyclic group or an optionally substituted heterocyclic group;
• with regard to R2A and R2B,
• R2A and R2B are taken together to form an optionally substituted methylidene group or an optionally substituted hydroxyimino group;
• R3 is a hydrogen atom, —OCH3 or —NH—CH(═O);
• R11 is
• ring E is an optionally substituted pyridinium ring or an optionally substituted fused ring containing pyridinium ring;
• R10 is a group represented by the formula:
• wherein
• ring A is a benzene ring, or a 6-membered aromatic heterocyclic group having 1-3 nitrogen atoms;
• k is an integer from 2 to 5;
• each R4 is independently a hydrogen atom, halogen, hydroxyl group, —CN, —C(═O)—R5, —C(═O)—OH, —C(═O)—OR5, or —OR5;
• R5 is a lower alkyl group or halo(lower)alkyl group;
• and
• G is a single bond, an optionally substituted lower alkylene group, an optionally substituted alkenylene group or an optionally substituted alkynylene group;
• M is a single bond or a 5- or 6-membered heterocyclic group containing at least 1 nitrogen atom;
• D is a single bond, —CO—, —O—CO—, —CO—O—, —NR6—, —NR6—CO—, —CO—NR6—, —NR6—CO—NR6—, —O—, —S—, —SO—, —SO2—NR6—, —NR6—SO2—, —CH2—NR6—CO— or —SO2—;
• each R6 is independently a hydrogen atom or an optionally substituted lower alkyl group;
• with the proviso that at least two R4 are hydroxyl groups which bind respectively to adjacent carbon atoms on ring A.