Rickettsia

Common card · No. 263089

Rickettsia is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The genus was named after Howard Taylor Ricketts in honor of his pioneering work on tick-borne spotted fever. Properly, Rickettsia is the name of a single genus, but the informal term "rickettsia", plural "rickettsias", usually not capitalised, commonly applies to any members of the order Rickettsiales. Being obligate intracellular bacteria, rickettsias depend on entry, growth, and replication within the cytoplasm of living eukaryotic host cells (typically endothelial cells). Accordingly, Rickettsia species cannot grow in artificial nutrient culture; they must be grown either in tissue or embryo cultures. Mostly chicken embryos are used, following a method developed by Ernest William Goodpasture and his colleagues at Vanderbilt University in the early 1930s. Many new strains...

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