101233-99-2 5H-1-Pyrindinium, 4-(((7-(((2-amino-4-thiazolyl)((carboxymethoxy)imino)acetyl)amino)-2-carboxy-8-oxo-5-thia-1-azabicyclo(4.2.0)oct-2-en-3-yl)methyl)thio)-6,7-dihydro-1-methyl-, hydroxide, inner salt, (6R-(6alpha,7beta(Z)))- 5H-1-Pyrindinium, 6,7-dihydro-4-(((7-(((2-amino-4-thiazolyl)((carboxymethoxy)imino)acetyl)amino)-2-carboxy-8-oxo-5-thia-1-azabicyclo(4.2.0)oct-2-en-3-yl)methyl)thio)-1-methyl-, hydroxide, inner salt, (6R-(6-alpha,7-beta(Z)))- ME 1221 MT 520