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RUSVM Bacteriology Gram Negatives > Rickettsiales > Flashcards

Flashcards in Rickettsiales Deck (61):
1

Rickettsiales description

Family Anaplasmataceae & Family Rickettsiaceae - Obligate intracellular gram negative bacteria -

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Family Anaplasmataceae

Anaplasma - Ehrilichia - Neorickettsia

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Anaplasma spp

Survive in cytoplasmic vacuoles of erythrocytes, phagocytes, platelets & myeloid cells

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Ehrlichia spp.

Survive in phagocytic cells

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Neorickettsia spp

Survive in macrophages & mononuclear cells

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Family Rickettsiaceae

Rickettsiae spp: R. rickettsia, wolbackia, oreintia

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Rickettsiae spp

Survive in vascular endothelium

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Anaplasma spp description

Gram negative, small coccoid-ellipsoid

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Anaplasma spp list

A. marginale, centrale, ovis, bovis, platys, phagocytophilum

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A. marginale

REPORTABLE, transmission with hard ticks (Ixodes), infects ruminants - Bovine anaplasmosis

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Bovine anaplasmosis

A. marginale - undulating febrile disease - Long-term carriage.

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When I say Bovine anaplasmosis, you say,

Anaplasma marginale!

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A. marginale pathogenesis in bovine

Bovine anaplasmosis! Erythrocytes engulf bacteria--> multiplication & release of new --> indiscriminate erythrocyte removal by host's macrophage system--> anemia, icterus, splenomegaly, hepatomegaly --> DESTRUCTION OF RBC!!

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Anaplasma platys

Infectious canine cyclic thrombocytopenia - Cycles of 1-2 week interval -

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Tick species that transmit Anaplasma platys

Rhiphicephalus & Dermacentor

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Anaplasma phagocytophilum

Tick borne fever in ruminants, human, equine - Canine granulocytic anaplasmosis - Transmitted by rodents & ixodes (hard ticks)

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What species causes canine granulocytic anaplasmosis?

A. phagocytophilum

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What species causes Infectious canine cyclic thrombocytopenia?

A. platys

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Rickettsiae - description

Small, gram negative, nonmotile (but hijacks actin in cells)

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Rickettsiae pathogenesis

Enter endothelials --> escape phagosome & multiply in cytoplasm & nucleus

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What disease is caused by Rickettsia rickettsia?

Rocky Mountain Spotted Fever

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What causes Rocky Mountain Spotted Fever?

Rickettsia rickettsia

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What does Rickettsia felis cause?

Typhus group

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What disease does Coxiella burnetii cause?

Q fever

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What causes Q fever?

Coxiella burnetii

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Rocky Mountain Spotted fever - Reservoir

Dogs & people, small mammals

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Rocky Mountain Spotted fever transmission

Dermecentor (Wood tick, American dog tick) (also transovarial & transtadial)

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Rickettsia ricketsii - Pathogenesis

In tick: replicate in epithelium--> to salivary glands & ovarian tissues - In vertebrate: Tick injects bacteria--> bacteria to endothelium, damage cell membrane --> vasculitis & thrombosis

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Rocky Mountain Spotted fever pathology

Rickettsia ricketsii - Severe necrosis in extremities, severe fatal disease (from vasculitis & thrombosis)

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Rocky Mountain Spotted fever DDx

Ehrlichiosis - Babesiosis - Baorreliosis

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Rocky Mountain Spotted fever prevention

Tick control, Tx with chloramphenicol, fluroquinolones, tetracyclines

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Coxiella burnetii General info

Survives in environment - have endospore-like growth phase - Can disseminate airborne - Bioweapon!! REPORTABLE

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Coxiella burnetii Hosts

Ticks, mites, lice, fleas ; Mammals

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Coxiella burnetii in humans

Q fever! subclinical influenza-like occupational disease - Endocarditis in chronic presentations

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Coxiella burnetii pathogenesis

inhalation/ingestion/arthropod bite --> vascular endothelium/renal & respiratory epithelia --> multiplies within phagosome - Persistent in lactating mammary gland and pregnant uterus

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Ehrlichiae general

WBC obligate intracellular bacteria - multiply within membrane lined intracytoplasmic vesicles

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Ehrlichiae genus

Ehrlichia & Neorickettsia - Tick transmitted species - Transtadially not transovarially

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Ehrlichiae spp Tx

Tetracyclines, imodocarb dipropionate - Doxy & steroid for late-stage, poor prognosis

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Ehrlichia canis Dz & transmission

Canine monocytic ehrlichiosis - Transmitted by Rhiphicephalus (brown dog tick)

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Ehrlichia canis pathogenesis

Inoculation by tick bite--> incubation --> severe acute dz develops, progresses to chronic (tropical canine pancytopenia) - Thrombocytopenia, leukopenia, anemia, secondary infections

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E. chaffensis

Human monocytic ehrlichiosis - Dermacentor (american dog tick) - Deer=reservoir

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What is the species of tick that transmits E. chaffensis

Dermacentor (American dog tick)

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E. ewingii

Canine granulocytic ehrlichiosis - Transmitted by Ambylomma americanum (Lone Star Tick)

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E. ruminantium

Africal heartwater - REPORTABLE - Ruminants in africa & caribbean - Some cattle breeds resistant

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E. ruminantium transmission

Amblyomma vector - parenteral introduction to blood

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E. ruminantium pathogenesis

Inoculation--> multiplication in reticuloendothelial cells lining lymph node sinusoids--> vascular dissemination & endothelial colonization --> vasculitis, pericardial effusion

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E. ruminatium Signs

Fever, followed by neurological signs (collapse & convulsions)

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Neorickettsia description

Small, non-motile, coccoid, intracytoplasmic vacuoles - In monocytes, macrophages, enterocyte - Vectors=Flukes

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Neorickettsia helminthoeca diseases

Salmon poisoning disease - Elokomin fluke fever (mild form)

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Neorickettsia helminthoeca - Pathogenesis

Dog ingests fluke-contaminated fish (encysted in salmon--> attachment & penetration of duodenal mucosa by trematode --> hemorrhagic enteritis w/bacterial spread to lymph node, spleen, liver, lungs, brain, thymus

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Neorickettsia helminthoeca - Life with the helminth

N. helminthoeca maintained by transovarial passage in the helminth, found throughout life cycle of the fluke - Only obligatory helminth borne pathogenic bacteria!

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Neorickettsia helminthoeca target cells

Canine mononuclear cells

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Neorickettsia helminthoeca Dx

Location, detection of fluke eggs, history of dog health

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Neorickettsia helminthoeca Prevention

Don't let dogs eat raw fish!

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Neorickettsia risticii

Potomac Horse Fever! - Equine monocytic ehrlichiosis - Equine sours

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When I say equine sours, you say

Neorickettsia risticii

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When I say Potomac horse fever, you say...

Neorickettsia risticii

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Neorickettsia risticii Target cells

Affinity for blood monocytes, tissue macrophages, intestinal epithelial cells

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Neorickettsia risticii - Reservoir

Infectious life cycle involves intermediate snail reservoir & trematode cercaria (proximity to bodies of water, summertime)

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Neorickettsia risticii clinical signs

Diarrhea

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Aegyptianellosis

Aegyptianella pullorum - Poultry & wild birds - Tick: Argus! - Lesions: hepatosplenomegaly, punctiform hemorrhages on serosal surfaces