(6R,7R)-3-[(4-carbamoylpyridin-1-ium-1-yl)methyl]-8-oxo-7-[(2-phenyl-2-sulfoacetyl)amino]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid
(6R,7R)-3-[(4-carbamoylpyridin-1-ium-1-yl)methyl]-8-oxo-7-[(2-phenyl-2-sulfo-acetyl)amino]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid
(6R,7R)-3-[(4-carbamoyl-1-pyridin-1-iumyl)methyl]-8-oxo-7-[(1-oxo-2-phenyl-2-sulfoethyl)amino]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid
(6R,7R)-3-[(4-carbamoylpyridin-1-ium-1-yl)methyl]-8-keto-7-[(2-phenyl-2-sulfo-acetyl)amino]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid
(6R,7R)-3-[(4-aminocarbonylpyridin-1-ium-1-yl)methyl]-8-oxo-7-[(2-phenyl-2-sulfo-ethanoyl)amino]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid