Synonyms: (2S,5R)-3,3-dimethyl-4,4,7-trioxo-4$l^{6}-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid; (6R,7R)-7-[[2-[(4-ethyl-2,3-dioxo-piperazine-1-carbonyl)amino]-2-(4-hydroxyphenyl)acetyl]amino]-3-[(1-methyltetrazol-5-yl)sulfanylmethyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid