(7aR,7R)-3-[({1-[(5R)-5-(4-carboxy-5-{[4-(2-hydroxyethyl)-5-thioxo-1,2,3,4-tetraazol-1-yl]methyl}-5H,2H,6H-1,3-oxazin-2-yl)-10,10-difluoro-5-methoxy-4,7-dioxo-6-aza-3-oxa-9-thiadec-1-yl]-1,2,3,4-tetraazol-5-yl}sulfanyl)methyl]-7-({2-[(difluoromethyl)sulfanyl]acetyl}amino)-7-methoxy-6-oxo-2,6,7,7a-tetrahydroazeto[2,1-b][1,3]oxazine-4-carboxylic acid