1-Azabicyclo(3.2.0)hept-2-ene-2-carboxylic acid, 3-((2-(acetylamino)ethenyl)thio)-6-ethyl-7-oxo-, monosodium salt, (5R-(3(E),5-alpha,6-alpha))- 73573-25-8 Antibiotic PS 7 sodium salt