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Microbiology > Lecture 16: Mycobacteria > Flashcards

Lecture 16: Mycobacteria Flashcards

1
Q

Mycobacteria are obligate ___

A

Aerobes

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2
Q

What are the shape of mycobacteria

A

Bacilli

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3
Q

What bacteria is this

A

mycobacteria

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4
Q

What type of bacteria are myobacteria

A

Acid fast

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5
Q

What structure of mycobacteria resist detergents and antibiotics

A

Mycolic acids and lipids in the cell wall

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6
Q

Mycobacteria are heat sensitive killed by pasteurization at __ degrees for ___secs

A

68.2 degrees C for 30 secs

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7
Q

How long does it take for pathogenic strains of mycobacteria to grow

A

3-6 weeks

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8
Q

What device can be used to speed up the growth of mycobacteria to ~15 days

A

BD BACTEC

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9
Q

What stain is used to differentiate mycobacteria from other bacteria

A

Ziehl-Neelsen stain

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10
Q

what is route of infection for mycobacteria

A

Inhalation or ingestion

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11
Q

What is the causative agent of Bovine tuberculosis

A

Mycobacterium bovis

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12
Q

Bovine tuberculosis is difficult to control d/t ___ reservoirs

A

Wildlife

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13
Q

T or F: bovine tuberculosis is zoonotic

A

True

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14
Q

How is bovine tuberculosis /M. Bovis transmitted among cattle

A

Aerosols or calves ingesting contaminated milk

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15
Q

What are the wild reservoirs for Bovine tuberculosis/ M. Bovis

A

Badgers, deer, elk, feral pigs

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16
Q

What is the pathogens is of Bovine TB/ M. Bovis

A
  1. Bacteria taken up by alveolar macrophages and dendritic cells
    2a. Dendritic cells—> migrate to LN—> lymphatic TB
    2b. M. Bovis survive in macrophages and prevent phagosome-lysosome fusion
  2. Infected macrophages secrete cytokines
  3. Recruit lymphocytes- granulomatous forms
  4. Collagen delineates the peripheral, bacteria are contained
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17
Q

Granuloma structure is defined mainly by what cells

A

Macrophages, T cells, and fibroblasts

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18
Q

Activated macrophages in bovine TB granuloma release __enzymes and result in what

A

Lytic enzymes that result in necrotic core with caseous (cheese-like) consistently

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19
Q

Granulomas in TB are called ___

A

Tubercles

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20
Q

What are the virulence factors for bovine TB/ M. Bovis

A

Surface proteins, mycolic acid

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21
Q

Necropsy of cow lung showed these lesions, what are they and what caused

A

tubercles, caused by M. Bovis

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22
Q

When are clinical signs evident in bovine TB

A

Advanced disease

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23
Q

What are some signs of advanced pulmonary TB in cows

A

Cough, intermittent fever

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24
Q

If bovine TB spreads via blood or lymphatics what can it result in (3)

A
  1. Tuberculous mastitis
  2. Supramammary LN enlargement
  3. Facilitates spread of infection to calves
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25
Q

What is the standard test to dx bovine TB

A

Tuberculin skin test

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26
Q

The tuberculin skin test is based on ___

A

Delayed type hypersensitivity

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27
Q

What is injected in tuberculin skin test

A

Purified protein derivative (PPD tuberculin)

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28
Q

What does a positive tuberculin skin test look like

A

Hard swelling at injection site

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29
Q

What can cause a false positive in a single intradermal caudal fold tuberculin test and what is solution

A

False positive can occur if animals are sensitized to mycobacteria other than M. Bovis

Run a comparative cervical test

30
Q

What is the comparative cervical tuberculin skin test

A

Inject 0.1mL of bovine PPd and 0.1mL of avian PPD into side of neck 12cm apart
Measure skin thickness before and 72hrs after

If skin thickness at bPPD site is 4mm thicker than aPPD site then +

31
Q

Why can false positives occur with tuberculin skin test

A

Immunosuppressive- stress, early post partum, drugs

32
Q

What are some blood based tests to diagnose bovine TB/ M. Bovis

A
  1. IGRA- interferon gamma release assay
  2. ELISA
33
Q

How does the IGRA test work to identify bovine TB and at what stage of disease does it identify

A

T cells activated and release IFN-y

Identifies slightly earlier stage of infection than tuberculin test

34
Q

How does the ELISA test work to identify Bovine TB and what stage of disease does it detect

A

Detects circulating antibodies, which are produced in later stages of disease

35
Q

What culture do you grow Bovine TB/ M. Bovis on

A

Lowenstein-Jensen medium

36
Q

How long does it take M. Bovis to grow on Lowenstein-Jensen medium

37
Q

What is the eradication program for bovine TB/M. Bovis

A
  1. Tuberculin testing
  2. Isolation
  3. Slaughter reactors
  4. Disinfect farm buildings
  5. Routine meat inspection
  6. Maintenance of wildlife reservoirs- culling
38
Q

What is the causative agent in Johne’s disease (paratuberculosis)

A

Mycobacterium avium subspecies paratuberculosis

39
Q

What type of bacteria is mycobacterium avium subspecies paratuberculosis

40
Q

Johne’s disease is a chronic, contagious, invariable ___

A

Fatal enteritis

41
Q

Who is most susceptible to Johne’s disease and what is the primary method of infection

A

Newborn animals, calves infected by accidental ingestion of feces

42
Q

Besides primary method of infection of Johne’s disease what are some other methods

A
  1. Infection in milk and colostrum
  2. In utero
43
Q

What is the pathogenesis of Johne’s disease

A
  1. Bacteria attach M cells in Peyer’s Patches
  2. Move across intestinal epithelium
  3. Taken up by macrophages
  4. Survive in macrophages by preventing phagosome-lysosome function
  5. Diseases progresses with granuloma formation in lamina propira and submucosal of GI tract
  6. Thickened and corrugated intestine
  7. Malabsorption of nutrients and water—> diarrhea
44
Q

What disease is this and what is cause

A

Johne’s disease caused by Mycobacterium avium subspecies paratuberculosis

45
Q

What are the main clinical manifestations of Johne’s disease/ MAP in cattle

A
  1. Diarrhea- first intermittent then profuse
  2. Weight loss without loss of appetite
  3. Death after 1 year initial detection
  4. SI and LI thickened and corrugated
46
Q

What are the clinical manifestations of Johne’s disease/ MAP in sheep and goats

A

Chronic weight loss

Diarrhea less marked or absent
Intestinal corrugating absent

47
Q

What are the clinical manifestations of Johne’s disease/ MAP in deer

A

Sudden onset diarrhea, rapid weight loss, death within 2-3wks

48
Q

How can you dx Johne’s disease

A
  1. Biopsies and acid fast stains
  2. Feces culture- Herrolds egg yolk medium
  3. BACTEC
  4. ELISA
  5. field test- Johnin PPD or IGRA
  6. PCR
  7. Post-mortem necropsy of intestine
49
Q

What field test can you do to identify Johne’s disease

A

Johnin PPD or IGRA

50
Q

What medium can you culture feces on to detect Johne’s disease

A

Herrolds egg yolk medium

51
Q

What test is this and what is it testing for

A

Herrolds egg yolk medium testing for Johne’s disease

52
Q

How do you control Johne’s disease

A
  1. Isolate animals with signs
  2. If confirm- cull immediately
  3. Monitor by PCR or culture of feces
53
Q

How do you prevent infection of Johne’s disease in young animals

A
  1. Separate from dams at birth
  2. Raise on pasteurized milk
  3. Remain isolated 2 years from herd
54
Q

What is the causative agent of poultry TB

A

Mycobacterium avium subspecies avium

55
Q

Where does mycobacterium avium subspecies avium/ Poultry TB infect

A

GI and disseminates liver and spleen

56
Q

What are the clinical signs of poultry TB

A

Dullness, lameness
Postmortem granulomas in spleen, liver, bone marrow and intestines

57
Q

How can you dx poultry TB

A
  1. Tuberculin test- avian PPD injection
  2. Postmortem
58
Q

What is tx for poultry TB

A

Macrolides

59
Q

What caused these lesions in the chicken

A

Mycobacterium avium subspecies avium- poultry TB

60
Q

What is the causative agent for feline leprosy

A

Mycobacterium lepraemurium

61
Q

What are the clinical signs of feline leprosy

A

SQ lesions, freely movable lesions, tend to ulcerate, small acid fast bacilli

62
Q

What is tx for feline leprosy

A

Surgical excision

63
Q

From cat, what dz and what caused it

A

Feline leprosy caused by mycobacterium lepraemurium

64
Q

what is answer in photo

A

Ziehl-Neelsen stain

65
Q

What is answer

A

Inhalation of aerosols

66
Q

What is answer

A

Mycobacteria prevents phagosome-lysosome fusion

67
Q

What is answer

A

Erythrocytes

68
Q

What is answer

69
Q

what is answer

A

Mycobacterium avium subspecies paratuberculosis

70
Q

What is the answer

A

profuse diarrhea

Microbiology (31 decks)

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