(2R)-2-(4-{[(2R)-2-[(3R)-8-cyano-5-oxo-4-aza-2-oxa-7-thiaoct-3-yl]-5-{[(1-methyl-1,2,3,4-tetraazol-5-yl)sulfanyl]methyl}-3H,6H,2H-1,3-thiazin-4-yl]carbonyl}-5-oxo-5-(thioformyl)-4-aza-2-oxapent-3-yl)-5-{[(1-methyl-1,2,3,4-tetraazol-5-yl)sulfanyl]methyl}-6H,2H,3H-1,3-thiazine-4-carboxylic acid