(2'R,4'S,4'aS)-9',10'-difluoro-8'-[(E)-N-hydroxy-C-methylcarbonimidoyl]-2',4'-dimethylspiro[1,3-diazinane-5,5'-2,4,4a,6-tetrahydro-1H-[1,4]oxazino[4,3-a]quinoline]-2,4,6-trione