The invention relates to the new arginine salt forms of S-(-)-9-fluoro-6,7-dihydro-8-(4-hydroxypiperidin-1-yl)-5-methyl-1-oxo-1H,5 H-benzo[i,j]quinolizine-2-carboxylic acid, a process for their preparation and pharmaceutical formulations which comprise those arginine salt forms as the active ingredient for its use in treating antimicrobial infections.

L'invention concerne les nouvelles formes de sel d'arginine de S-(-)-9-fluoro-6,7-dihydro-8-(4-hydroxypiperidin-1-yl)-5-methyl-1-oxo-1H,5 H-benzo[i, d'acide de j]quinolizine-2-carboxylic, d'un procédé pour leur préparation et de formulations pharmaceutiques qui comportent ces formes de sel d'arginine comme substance active pour son usage dans des infections antimicrobiennes de traitement.