MT-520
ME 1221
4-[[[(7R)-7β-[[(Z)-(2-Aminothiazol-4-yl)[(carboxymethoxy)imino]acetyl]amino]-4-carboxylatocepham-3-en-3-yl]methyl]thio]-6,7-dihydro-1-methyl-5H-1-pyrindin-1-ium
1-Methyl-6,7-dihydro-4-[[[4-carboxy-7β-[[(Z)-(2-aminothiazol-4-yl)[(2-hydroxy-2-oxoethoxy)imino]acetyl]amino]cepham-3-en-3-yl]methyl]thio]-5H-cyclopenta[b]pyridin-1-ium
