Ricketssia And Miscallaneous Bacteria Flashcards
Ricketssiae features
Obligate intracellular organism
Cannot grow on artificial media
Grow in cell lines only
Ricketssiae infection is transmitted by
Arthropod borne transmission except Coxiella (inhalational)
Rash can be seen in all Ricketssial infections except
Coxiella
Pathogenesis of Ricketssial infections
Reservoir host - vector - humans - multiply locally and enter blood stream - localise at endothelium - degenerate and thrombosis - Occlusion
Epidemic typhus cause and transmitted by
R. Prowazekii
Louse
Endemic typhus cause and transmitted by
R. Typhi
Flea
Rocky mountain spotted fever cause and vector
R. Ricketsii
Tick
Cause of African tick typhus and vector
R. Conori
Tick
Cause of Ricketssial pox and vector
R. Akari
Mite
Scrub typhus is caused by and Vector
Orientia tsutsugamushi
Mite
Mnemonic of Ricketssial infections
LET - Louse epidemic typhus
FEN - Flea Endemic typhus
TRIA - Tick RMSF Indian tick and African tick typhus
PSM - Ricketssial pox, Scrub typhus, Mite
Louse features in case of Epidemic typhus
On fever, louse leaves body (sensitive to heat)
Not a zoonotic disease
Infection is transmitted by entry of Louse feces into body via abrasions
Incubation period of Epidemic typhus/Jail fever
5-15 days
Clinical features of Epidemic typhus
Fever , Chills
After 4-5 days, Rash first appear on trunk and then limbs - Delirious - fatal
All Ricketssial infections causes rash first on trunk and then limbs except
Rocky Mountain spot fever - starts from extremities then goes to trunk
Brill zinser disease is due to
Reactivation of Epidemic typhus
Less severe
No vector
Neil mooser reaction/Tunica reaction is shown by
R. Prowazekii - negative Reaction
R. Typhii (Endemic typhus) - Positive reaction
Procedure of Neil mooser reaction/Tunica reaction
Intraperitoneal inoculation of guinea pig with blood from case - Scrotal inflammation - +ve Reaction
Scrub typhus is also known as
Chigger borne disease
Zoonotic tetrad of Scrub typhus
Chiggers larvae - transported by trombiculid mites, Carry infection in Rats/Squirrel, Infect humans, Present in vegetation/Shrubs
Pathogenesis of Scrub typhus
Mite larvae/Chiggers - Seek moist areas of body (Axilla, groin) - After 1-3 weeks Eschars at site of bite along with Fever , Nausea, vomiting, Lymphadenopathy
Complications of Scrub typhus
Pneumonia, ARDS, Shock
Special stains used for diagnosis of Ricketssial organisms
Giemsa
Castaneda
Gimenez
Macchiavello
Culture used in Ricketssial infections
Yolk sac of embryonated hen’s egg
Cell lines (Vero, Hela, Hep2, Detroit 6)
Serological test done for diagnosis of Ricketssial infections
Weil Felix reaction
IgM (ELISA)