80. Rickettsiales (habitat, morphology, staining, culture). Genus Rickettsia.

Question 1

Systematics of Rickettsiales?

Answer 1

Systematics of Rickettsiales
Rickettsiaceae family (cell wall contains peptidoglycane layer)
Coxiella genus C. burnetii
Ehrlichia E. canis
E. ruminantium
Rickettsia R. rickettsii
R. prowazekii
R. sibirica
R. conorii
Neorickettsia N. risticii
Anaplasmataceae family (no cell wall)

Question 2

Systemaics of Rickettsiales?

Answer 2

Systematics of Rickettsiales
Anaplasmataceae family (no cell wall, cytoplasmamembrane only)
Anaplasma A. marginale
A. centrale
A. bovis
A. ovis
A. phagocytophilum

Question 3

Habitat Morphology and staining?

Answer 3

RICKETTSIALES
Habitat
• obligate cell parasites, arthropod vectors, small
rodents
Morphology
• 0.3-0.8 µm coccoid rods, non motile
Staining
• difficult
• Giemsa, Köster, Stamp

Question 4

Culture,classification and Genera?

Answer 4

Culture
• living cells
• embryonated eggs, cell culture, animals
Classification
• cell tropism
• intra or extra cellular propagation
• vector
Genera
• Rickettsia, Coxiella: propagate in all cell types
• Ehrlichia, Neorickettsia: lymphoid cells, endothel cells
• Anaplasma: in or on erythrocytes, in lymphoid cells

Question 5

Rickettsia genus?

Answer 5

RICKETTSIA genus
Habitat
• reservoir: rodents and arthropods
Pathogenicity
• R. prowazekii: Epidemic Typhus fever – louse
• R. rickettsii: Rocky Mountain spotted fever – ticks
(America)
• R. sibirica: North-Asian tick-borne rickettsiosis – ticks
• R. conorii: Boutouneuse-fever – ticks
(Mediterranean area)