Penem derivative of the formula 1
in which
R is hydrogen or a carboxyl esterifying group, R 1 is phenyl, napthyl, thienyl, pyridyl, quinolyl or isoquinolyl being unsubstituted or substituted by one, two or three of the same or different substituents selected from halogen, hydroxy, amino, nitro, cyano, azido, alkyl, alkoxy, alkanesulfenyl, alkanesulfinyl, alkanesulfonyl, alkanoyl, alkoxycarbonyl, alkanoyloxy, carbamoyl, ureido, carba- moyloxy, alkanoylamino, aminosulfamoyl, sulfamoyl, guani- dino, trifluormethyl, trifluormethanesulfenyl, trifluor- methanesulfinyl, trifluormethanesulfonoyl and formyl, which may be substituted by one, two or three lower alkyl groups being the same or different. R 2 represents a hydrogen atom or a optionally protected hydroxyl group, or a salt thereof,
process for the production thereof and antibacterial pharmaceutical preparations comprising them.