5.13 Obligate Intracellular Bacteria Flashcards
what are the 2 intracellular orders
Rickettsiales and Chlamydiales
what is the shape and staining properties of Rickettsiales and Chlamydia
Gram-negative coccobacilli; stain with Wright or Giemsa
how do we diagnose Rickettsiales or Chlamydia spp.
direct stain, PCR, serology, growth in cells
what are the 2 families of Rickettsiales
Rickettsiaceae and Anaplasmataceae
what is the chlamydiales family
Chlamydiaceae
what are the genus of Rickettsiaceae (1) and Anaplasmataceae (3)
Rickettsiaceae: Rickettsia
Anaplasmataceae: Neorickettsia, Anaplasam, Erlichia
what are the genus of Chlamydiaceae (2)
Chlamydia and Chlamydophila
Anaplasmataceae (Neorickettsia, Anaplasma and Erlichia) are parasites of what cells and what host type
hematopoietic cells; vertebrate hosts
Neorickettsia is transmitted by _________ whereas Erlichia and Anaplasma are transmitted by
trematode; ticks
A. phagocytophilum infects what cells
neutrophils
Anaplasma phagocytophilum is the same as Borrelia burgdoferi because ________ and different because __________
transmitted by Ixodes and maintained in small mammals; is not maintained in birds
what does Anaplasma phagocytophilum cause in dogs
neutropenia, thrombocytopenia, mm pain, necrotizing vasculitis
what does Anaplasma phagocytophilum cause in horses
DIC, limb edema, jaundice
what does Anaplasma phagocytophilum cause in ruminants
no illness to subclinical disease
what does Anaplasma phagocytophilum cause in people
granulocytic erlychiosis
what can we use to diagnose Anaplasma phagocytophilum
direct demo in buffy coat, PCR, SNAP test
how do we treat and control Anaplasma phagocytophilum
treat: tetracycline
control: tick control (same as lyme disease mitigation)
what is the vector for Ehrlichia spp.
ticks
what cells does Ehrlichia spp. infect
hematopoietic cells and endothelial cells
what is the source of Ehrlichia infections
rodents, canids or ruminants that are persistently infected
what are the 3 manifestations of Ehrlichia canis infection
1) acute infection
2) persistent subclinical infection
3) severe, immune-mediated chronic disease
how do we treat Ehrlichia canis
tetracycline
describe the outcomes of Ehrlichia canis infection:
- acute
- persistent subclinical
- chronic, severe immune-mediated
acute: fever, mild anemia, thrombocytopenia, lymphadenopathy, vasculitis
persistent subclinical: mild anemia, fever, thrombocytopenia
chronic, severe immune-mediated: bleeding, epistaxis, vasculitis, weight loss, secondary infections
where is Ehrlichia canis more present
Southern USA (since more brown dog ticks -> Rhipencephalus sanguineus)
what causes canine granulocytic erlichiosis, which is spread by Ixodes scapularis, presents like A. phagocytophilum and is often concurrent with A. phagocytophilum and B. burgdoferi
Ehrclichia ewingii and Ehrlichia chaffeensis
what cells does Neorickettsia infect
monocytes and macrophages
what is the vector for Neorickettsia spp.
trematode (flukes)
what causes salmon poisoning in dogs
Neorickettsia helminthoeca; an intestinal fluke of salmon containing the pathogen is consumed by dogs
what is the causative agent of Potomac Horse Fever
Neorickettsia risticii
how is N. risticii (Potomac Horse Fever) spread and
trematodes in bats (final host), aquatic snails (first intermediate host) and aquatic insects (second intermediate host)
horses drink water infested with the aquatic insects (ex. mayflies, caddis flies)
what are clinical signs of Potomac Horse Fever caused by Neorickettsia risticii
- fever
- anorexia
- leukopenia
- laminitis
- severe diarrhea
why does Neorickettsia risticii cause diarrhea
the pathogen infects macrophages in the colon glandular epithelium (as well as in the intestinal lamina propria and monocytes in blood)
how do we diagnose Potomac Horse Fever (N. risticii)
Buffy coat PCR
how do we treat (2) and control (1) Potomac Horse Fever (N. risticii)
vaccination (not 100% due to antigenic variants) and tetracycline; control flies (ex. keep lights low)
what cells do Chlamydia/Chlamydophila infect)
epithelial cells
how is Chlamydia/Chlamydophila spread
in dried feces; typically animal-animal contact
what are the 2 stages of Chlamydia/Chlamydophila’s life cycle? explain in detail
Elementary bodies (EB) and Reticulate bodies (RB):
EB: Extracellular stage including attachment and entry into the cell, replication and cell death
RB: Intracellular stage from cell death to dissemination into a new host cell
what is the agent of Psittacosis
Chlamydophila psittaci
what does C. psittaci cause
systemic infection: conjunctivitis, hepatomegaly, splenomegaly, bronchopneumonia, bronchiolitis, fibrinous polyserositis
what is the pathogenesis of Psittacosis
EBs are shed by carriers (feces) or infected birds (secretions) -> inhaled -> replicates in epithelial and phagocytic cells -> multi-organ infection
how do we diagnose C. psittaci
PCR, serology, Giemsa stain
how do we control and treat C. psittaci
Treat: tetracycline
Prevent: isolate and quarantine imported birds
what does Chlamydophila abortus cause and in what species?
- enzootic abortion in sheep/goats
- pneumonia
- infertility
- conjunctivitis
- arthritis
(other signs besides abortion occur in cattle as well)
how do we diagnose Chlamydophila abortus
Giemsa staining, egg isolation, PCR
how do we treat and control Chlamydophila abortus
tetracyclines, vaccination (in sheep)
what is the agent of Q fever
Coxiella burnetii
Coxiella burnetii is a “_______ ________ _________ “ pathogen
broad host range (endemic in ruminants, causes disease in humans, subclinical in cats)
what makes Coxiella burnetii highly persistent
endospore-like form
in what animals will Coxiella burnetii persist subclinically and what is the consequence
in carrier females; released in huge amounts at parturition
how is Coxiella burnetii spread
usually by inhalation but also ingestion or tick-borne; present in milk, birth fluids, urine and feces
what is important for Coxiella burnetii transmission
dust
how do we diagnose Coxiella burnetii
PCR, serology, direct-demonstration
how do we treat and control Coxiella burnetii
treat with tetracyclines; control with hygeine, education, early diagnosis, vaccination
