(7aR,7R)-3-[({1-[(6R)-6-[(2R)-4-carboxy-5-methylidene-5H,6H,2H-1,3-oxazin-2-yl]-11,11-difluoro-6-methoxy-5,8-dioxo-7-aza-3-oxa-10-thiaundec-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