立氏立克次体（英语：Rickettsia rickettsii），一种单细胞、革兰氏阴性的立克次体，是落矶山斑点热的病原体，原生于美洲。

医学导航：病菌

细菌（分类）

gr+f／gr+a（t）／gr-p（c／gr-o

药物（J1p、w、n、m、疫苗）

Rickettsia rickettsii (abbreviated as R. rickettsii) is a gram-negative, intracellular, coccobacillus bacterium that is around 0.8 to 2.0 micrometers long. R. rickettsi is the causative agent of Rocky Mountain spotted fever. R. rickettsii is one of the most pathogenic Rickettsia strains known to humans and affects a large majority of the Western Hemisphere and small portions of the Eastern Hemisphere.