6-((aminophenylacetyl)amino)-3,3-dimethyl-7-oxo-4- thia-1-azabicyclo(3.2.0)heptane-2-carboxylic acid,mixt. with 6-(((3-(2-chlorophenyl)-5-methyl-4-isox azolyl)carbonyl)amino)-3,3-dimethyl-7-oxo-4-thia-1- azabicyclo(3.2.0)heptane-2-carboxylic acid