Disclosed is the use of (3S)-3-{ (2Z)-2-(2-amino(1,3-thiazol-4-yl))-3-[(1,5-dihydroxy-4-oxo(2-hydropyridyl))methoxy]-3-azaprop-2-enoylamino} -4,4-dimethyl-2-oxoazetidinyl hydroxysulfonate of formula (I) wherein the oxyimino group i.e. >；C=N-O- has Z-orientation, or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of a bacterial infection in combination with one or more than one carbapenem antibiotic, which is a compound of formula (II) e.g. meropenem where the substituents are defined in the specification.
