Polymorphs of N-((S)-3-amino-1-(hydroxyamino)-3-methyl-1-oxobutan-2-yl)-4-(((1R,2R)-2-(hydroxymethyl)cyclopropyl)buta-1,3-diynyl)benzamide (Compound I) are provided. Processes for making the same, as well as related compositions and methods, are also disclosed, particularly with regard to the treatment of bacterial infections.本發明提供N-((S)-3-胺基-1-(羥胺基)-3-甲基-1-酮基丁-2-基)-4-(((1R,2R)-2-(羥甲基)環丙基)丁-1,3-二炔基)苯甲醯胺(化合物I)之多晶型。本發明亦揭示其製備方法,以及相關組合物及方法,尤其關於細菌感染之治療。