Mycobacteria Flashcards

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1
Q

what are the general characteristics of Mycobacteria? (aerobic status, shape, spores?, gram/acid?, heat sensitivity?)

A

obligate aerobes
bacilli
non-spore forming
acid-fast bacteria
heat sensitive

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2
Q

why does Mycobacterium not take up gram stain dyes?

A

high concentration of mycolic acids and lipids

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3
Q

what is an effective way to kill Mycobacterium?

A

pasteurization b/c bacteria is heat sensitive

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4
Q

How long does it take for pathogenic mycobacterium to grow?

A

3-6w

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5
Q

what stain is used to differentiate mycobacteria from other bacteria?

A

Ziehl-Neelsen

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6
Q

Are there few or many mycobacterium species?

A

many many many

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7
Q

How is mycobacterium transmitted?

A

inhaled and ingested

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8
Q

List the clinically relevant veterinary mycobacterial series?

A

bovine tuberculosis, Johne’s disease, poultry tuberculosis, feline leprosy

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9
Q

what is the causative agent of bovine tuberculosis?

A

Mycobacterium bovis

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10
Q

what are the main concerns with bovine tuberculosis?

A

causes production loss
difficult to control due to wildlife reservoirs
human to cattle infection possible

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11
Q

Why are the cases of Bovine tuberculosis low in the US compared to earlier times?

A

eradication programs

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12
Q

Is bovine tuberculosis zoonotic?

A

yes

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13
Q

How is Bovine tuberculosis transmitted?

A

through aerosols, ingesting contaminated milk

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14
Q

what are the wildlife reservoirs for bovine tuberculosis?

A

badgers, deer, elk, feral pigs

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15
Q

Describe the pathogenesis of Bovine tuberculosis

A
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16
Q

what happens when Mycobacterium bovis is taken up by alveolar macrophages vs dendritic cells? (end result)

A

alveolar macrophages - granuloma formation, bacteria contained
dendritic cells - lymphatic tuberculosis

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17
Q

Which mycobacterium species can spread from humans to dogs?

A

Mycobacterium tuberculosis

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18
Q

What causes the necrotic and caseous lesions seen with bovine tuberculosis?

A

lytic enzymes released by activated macrophages

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19
Q

Explained how Bovine tuberculosis that is cleared or latent can be reactivated

A

granulomas contain infection > no signs of disease > bacteria survive inside granuloma > bacteria reemerge and cause disease

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20
Q

what are granulomas in tuberculosis called?

A

tubercles

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21
Q

what are the arrows pointing at on these animals?

A

tubercles

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22
Q

When are the clinical signs seen with bovine tuberculosis?

A

only evident in advanced disease

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23
Q

what are the symptoms of advanced pulmonary tuberculosis?

A

cough, fever

24
Q

what are the symptoms seen when tuberculosis is spread via blood or lymphatics? How is the advantageous transmission?

A

tuberculosis mastitis > facilitated spread of infection to calves

25
Q

How is bovine tuberculosis diagnosed?

A

tuberculin skin test
blood-based test
Isolation for M. bovis

26
Q

Describe the tuberculin skin test (hypersensitivity and preparation)

A

delayed-type hypersensitivity
purified protein derivative is prepared from mycobacteria

27
Q

what is a positive tuberculin skin test?

A

hard swelling at injection site

28
Q

what are the two types of tuberculin skin test?

A

single intradermal (caudal fold) test
Comparative cervical test

29
Q

what test is this?

A

single intradermal (caudal fold) tuberculin skin test

30
Q

what test is this?

A

comparative cervical tuberculin skin test

31
Q

Which tuberculin skin test can have a false positive results? How?

A

Single intradermal (caudal fold) test
animals sensitized to mycobacteria other than M. bovis

32
Q

when do false negatives occur with tuberculin skin tests?

A

immunosuppresion - stress, early post partum, drugs

33
Q

what are the two blood-based tests to diagnose bovine tuberculosis?

A

IGRA and ELISA

34
Q

what medium is used to isolate M. bovis? How long does it take to grow?

A

Lowenstein-Jensen medium
8 weeks

35
Q

which tuberculin skin test would you want to use for a herd of cattle that lives on a ranch with poultry?

A

Comparative cervical test

36
Q

what is the control in the comparative cervical test?

A

M. avium

37
Q

How is Bovine tuberculosis treated?

A

treatment not part of control programs > slaughter of reactors and disinfection of farm buildings

38
Q

what is the causative agent of Johne’s disease?

A

M. avium subsp. paratuberculosis (MAP)

39
Q

what is Johne’s disease also called?

A

Paratuberculosis or MAP infection

40
Q

Select one term in each pair for Johne’s disease
acute/chronic
environmental/contagious
treatable/fatal

A

chronic, contagious, invariably fatal enteritis

41
Q

what animals are most susceptible to MAP infection?

A

newborn animals

42
Q

how are calves infected with MAP?

A

accidental ingestion of feces

43
Q

How are infections with MAP recorded in cattle?

A

milk and colostrum

44
Q

What is the pathogeneis of Johne’s disease?

A

bacteria attach M cells > taken up by macrophages > survive within macrophages by preventing phagosome-lysosome fusion > granuloma formation >thickened and corrugated intestine > malabsorption and diarrhea

45
Q

what is the causative agent?

A

Mycobacterium avium subsp. paratuberculosis

46
Q

what are the main clinical symptoms of Johne’s disease in cattle?

A

diarrhea, SI and LI thickened and corrugated

47
Q

what are the main clinical symptoms of Johne’s disease in sheep and goats?

A

chronic weight loss

48
Q

what are the main clinical symptoms of Johne’s disease in deer?

A

diarrhea, rapid weight loss

49
Q

How is Johne’s disease diagnosed through fecal culture? How long does it take?

A

Herrold’s egg yolk medium
8-12w

50
Q

what is a rapid radiological method to measure growth of MAP?

A

BACTEC

51
Q

what is a field test that can be done to detect Johne’s disease?

A

Johnin PPD or IGRA

52
Q

what is the post-mortem way of diagnosing Johne’s disease?

A

necropsy

53
Q

How is Johne’s disease controlled?

A

isolate animals with MAP signs
confirmed animals cull

54
Q

Since detection and elimination of subclinical infection with Johne’s is difficult how should it be monitored?

A

PCR or culture of feces

55
Q

What should you suggest to herds that have had repeat cases of MAP?

A

proper hygiene/husbandry

56
Q

Is there a vaccine for Johne’s disease?

A

no but vaccine trials are showing promising results - in the making

57
Q

what is the causative agent of poultry tuberculosis?

A

Mycobacterium avium subsp. avium