ME 1228;(6R,7R)-7α-[[(2-Aminothiazol-4-yl)[(Z)-[(R)-1-carboxyethoxy]imino]acetyl]amino]-3-[(1-ethylpyridinium-4-yl)thiomethyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid anion;(6R,7R)-7-[[(2E)-2-(2-amino-1,3-thiazol-4-yl)-2-[(1S)-1-carboxyethoxy]iminoacetyl]amino]-3-[(1-ethylpyridin-1-ium-4-yl)sulfanylmethyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate
