106061-25-0 ME 1220 ME-1220 Pyridinium, 4-(((7-(((2-amino-4-thiazolyl)(ethoxyimino)acetyl)amino)-2-carboxy-8-oxo-5-thia-1-azabicyclo(4.2.0)oct-2-en-3-yl)methyl)thio)-1-(carboxymethyl)-, hydroxide, inner salt, (6R-(6alpha,7beta(Z)))-