Synonyms: 1-[(7-Amino-2-carboxy-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl)methyl]pyridiniumhydroxide, inner salt (7CI); Pyridinium,1-[(7-amino-2-carboxy-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl)methyl]-,hydroxide, inner salt (8CI); Pyridinium,1-[(7-amino-2-carboxy-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl)methyl]-,inner salt, (6R-trans)-;N-(7-Aminoceph-3-em-3-ylmethyl)pyridinium-4-carboxylate;N-(7-Aminocephem-3-em-3-ylmethyl)pyridinium-4-carboxylate;[7-Amino-3-(1-pyridylmethyl)-3-cephem-4-carboxylic acid