Mycobacterial Diseases Flashcards
how do cattle get Mycobacteria spp?
inhalation
ingestion
what is the hallmark of mycobacterial disease in humans and animals?
granuloma
what are some common themes of all mycobacterial diseases?
emaciated on physical exam
nodules anywhere on body: physical exam, granulomas on necropsy
thickened tissues: physical exam and necropsy
mycobacteria possess virulence factors that cause ______________________________
necrosis/inflammation
what virulence factors do mycobacteria have that promote necrosis?
cell wall: trehalose dimycolate
secreted proteins: ESAT-6, CFP-10
how do mycobacteria resist antimicrobial effects of phagosomes?
inhibit phagolysosome fusion: poor lysosome acidification
how do mycobacteria impair antigen presentation?
diminish expression of MHCI and MHCII
how do mycobacteria live outside of cells?
necrotic centers of granulomas
common TB diagnostic tests detect ___________________________________
memory T cell responses
how do we interact with bovine tuberculosis and cattle now?
test live cattle to identify “reactors” and slaughter
look for granulomas at slaughter: culture, PCR
what is the major reservoir of bovine tuberlucosis in the UK and ireland?
badgers
what is the reservoir of bovine tuberculosis in the US?
white tailed deer
what type of pneumonia does tuberculosis cause?
granulomatous pneumonia
what pathogen causes bovine tuberculosis?
Mycobacterium bovis
what is the route of infection of Mycobacterium avium subspecies paratuberculosis in ruminants?
fecal-oral: milk from dirty teat
GI tract
Peyer’s patches
macrophages
chronic granulomatous enteritis
wasting
death
what is the signalment and signs of Johne’s disease in cattle?
> 2 years old, cachexic
diarrhea, chronic or intermitteent
no mucus, no blood, no tenesmus
no fever
is there a vaccine for Mycobacterium avium subspecies paratuberculosis in cattle?
yes, but not great
when is Johne’s disease typically diagnosed?
more than 2 years old
why may animals take years to show symptoms of Johne’s disease?
slowly progressive, wasting
why must age be taken into account when choosing diagnostic tests?
many tests are less sensitive for animals <18 months
who can get Mycobacteria spp via ingestion?
humans
cattle
cats
who can get Mycobacteria spp via contact?
cats
humans
what does necrosis contribute to?
macrophage death
granuloma necrosis
lung tissue infarction
cavitation
neutrophils
fibrosis
how do Mycobacteria achieve metabolic quiescence (latency)?
survives nutrient deprivation and hypoxia
what protective enzymes do Mycobacteria produce?
arginases degrade reactive nitrogen species
how do Mycobacteria mannipulate phagocytosis?
entry through mannose receptor is anti-inflammatory
Mycobacteria can induce antigen-specific tolerant __________
T cells
what does an indirect ELISA detect for M bovis?
antibodies against MPB93 and MPB70
what is the reservoir in South Africa of tuberculosis?
cape buffalo
what has Mycobacterium tuberculosis shown?
reverse zoonosis
captive elephants exposed by handlers
what are the concerns with tuberculosis?
affects many species
public health concern
wildlife conservation concern
food animal concern
what is the transmission route for Johne’s disease (Mycobacterium avium subsp paratuberculosis)?
fecal-oral
how is diagnosis of Johne’s disease different than other mycobacterial diseases?
test of cell-mediated immunity often does not work well
what are the preferred ways to diagnose Johne’s diseasse?
PCR or culture
PCR: IS900 unique genetic element in Mycobacterium avium subsp paratuberculosis
