(2R)-2-[(4Z,8R)-9-({4-[(4Z,8R)-9-({4-[(4Z)-6-{[(5aR,6R)-1,7-dioxo-1,3,4,5a,6,7-hexahydroazeto[2,1-b]furo[3,4-d][1,3]thiazin-6-yl]amino}-2-carboxy-2-methyl-6-oxo-4-aza-3-oxahex-4-en-5-yl]-1,3-thiazol-2-yl}amino)-2-carboxy-8-[(2R)-4-carboxylato-5-(pyridin-1-ium-1-ylmethyl)-2H,3H,6H-1,3-thiazin-2-yl]-2-methyl-6,9-dioxo-4,7-diaza-3-oxanon-4-en-5-yl]-1,3-thiazol-2-yl}amino)-5-(2-amino-1,3-thiazol-4-yl)-2-carboxy-2-methyl-6,9-dioxo-4,7-diaza-3-oxanon-4-en-8-yl]-5-(pyridin-1-ium-1-ylmethyl)-6H,2H,3H-1,3-thiazine-4-carboxylate