(7aR,7R)-7-{[(3Z)-4-(2-furyl)-5-oxo-3-aza-2-oxapent-3-en-5-yl]amino}-3-{5-[(7aR,7R)-7-amino-3-[(carbamoyloxidanyl)methyl]-6-oxo-2,6,7,7a-tetrahydroazeto[2,1-b][1,3]thiazin-4-yl]-3,5-dioxo-4-aza-2-oxapent-1-yl}-6-oxo-2,6,7,7a-tetrahydroazeto[2,1-b][1,3]thiazine-4-carboxylate ammonium