1993
Refers to nonmotile, Gram-negative, nonspore-forming, highly pleomorphic bacteria.
They appear in the forms of cocci 0.1 μm in diameter, rods 1–4 μm long, or threads up to about 10 μm long.
That are obligate intracellular parasites, that depend on entry, growth, and replication within the cytoplasm of living host cells, usually endothelial cells.
Rickettsial organisms invade vascular endothelial cells in target organs, damaging them and producing increased vascular permeability with consequent edema, hypotension, and hypoalbuminemia.
Rickettsia species, therefore cannot grow in artificial nutrient culture, and must be grown either in tissue or embryo cultures.
Rickettsia are transmitted by a number of types of Arthropods, including: chigger, ticks, fleas, and lice.
Rickettsia species are the pathogens responsible for typhus, rickettsialpox, boutonneuse fever, African tick-bite fever, Rocky Mountain spotted fever, Flinders Island spotted fever, and Queensland tick typhus.
Rickettsia bacteria are generally susceptible to antibiotics of the tetracycline group.
The classification of Rickettsia into three groups- spotted fever, typhus, and scrub typhus.