34409-23-9 BL-S 217 BRN 4167854 Pyridinium, 4-((2-((3-((acetyloxy)methyl)-2-carboxy-8-oxo-5-thia-1-azabicyclo(4.2.0)oct-2-en-7-yl)amino)-2-oxoethyl)thio)-1-methyl-, hydroxide, inner salt, (6R-trans)-