Disclosed are 3-substituted-6-(1'-hydroxyethyl)-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acids having the structure: ##STR1## wherein R.sup.8 is, inter alia, selected from the group consisting of hydrogen, alkyl, alkenyl, aryl and aralkyl. Such compounds as well as their pharmaceutically acceptable O- and carboxyl derivatives are useful as antibiotics. Also disclosed are processes for the preparation of such compounds, pharmaceutical compositions comprising such compounds and methods of treatment comprising administering such compounds and compositions when an antibiotic effect is indicated.