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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
What is the standard test to dx bovine TB
Tuberculin skin test
26
The tuberculin skin test is based on ___
Delayed type hypersensitivity
27
What is injected in tuberculin skin test
Purified protein derivative (PPD tuberculin)
28
What does a positive tuberculin skin test look like
Hard swelling at injection site
29
What can cause a false positive in a single intradermal caudal fold tuberculin test and what is solution
False positive can occur if animals are sensitized to mycobacteria other than M. Bovis Run a comparative cervical test
30
What is the comparative cervical tuberculin skin test
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
Why can false positives occur with tuberculin skin test
Immunosuppressive- stress, early post partum, drugs
32
What are some blood based tests to diagnose bovine TB/ M. Bovis
1. IGRA- interferon gamma release assay 2. ELISA
33
How does the IGRA test work to identify bovine TB and at what stage of disease does it identify
T cells activated and release IFN-y Identifies slightly earlier stage of infection than tuberculin test
34
How does the ELISA test work to identify Bovine TB and what stage of disease does it detect
Detects circulating antibodies, which are produced in later stages of disease
35
What culture do you grow Bovine TB/ M. Bovis on
Lowenstein-Jensen medium
36
How long does it take M. Bovis to grow on Lowenstein-Jensen medium
8weeks
37
What is the eradication program for bovine TB/M. Bovis
1. Tuberculin testing 2. Isolation 3. Slaughter reactors 4. Disinfect farm buildings 5. Routine meat inspection 6. Maintenance of wildlife reservoirs- culling
38
What is the causative agent in Johne’s disease (paratuberculosis)
Mycobacterium avium subspecies paratuberculosis
39
What type of bacteria is mycobacterium avium subspecies paratuberculosis
Acid fast
40
Johne’s disease is a chronic, contagious, invariable ___
Fatal enteritis
41
Who is most susceptible to Johne’s disease and what is the primary method of infection
Newborn animals, calves infected by accidental ingestion of feces
42
Besides primary method of infection of Johne’s disease what are some other methods
1. Infection in milk and colostrum 2. In utero
43
What is the pathogenesis of Johne’s disease
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
What disease is this and what is cause
Johne’s disease caused by Mycobacterium avium subspecies paratuberculosis
45
What are the main clinical manifestations of Johne’s disease/ MAP in cattle
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
What are the clinical manifestations of Johne’s disease/ MAP in sheep and goats
Chronic weight loss Diarrhea less marked or absent Intestinal corrugating absent
47
What are the clinical manifestations of Johne’s disease/ MAP in deer
Sudden onset diarrhea, rapid weight loss, death within 2-3wks
48
How can you dx Johne’s disease
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
What field test can you do to identify Johne’s disease
Johnin PPD or IGRA
50
What medium can you culture feces on to detect Johne’s disease
Herrolds egg yolk medium
51
What test is this and what is it testing for
Herrolds egg yolk medium testing for Johne’s disease
52
How do you control Johne’s disease
1. Isolate animals with signs 2. If confirm- cull immediately 3. Monitor by PCR or culture of feces
53
How do you prevent infection of Johne’s disease in young animals
1. Separate from dams at birth 2. Raise on pasteurized milk 3. Remain isolated 2 years from herd
54
What is the causative agent of poultry TB
Mycobacterium avium subspecies avium
55
Where does mycobacterium avium subspecies avium/ Poultry TB infect
GI and disseminates liver and spleen
56
What are the clinical signs of poultry TB
Dullness, lameness Postmortem granulomas in spleen, liver, bone marrow and intestines
57
How can you dx poultry TB
1. Tuberculin test- avian PPD injection 2. Postmortem
58
What is tx for poultry TB
Macrolides
59
What caused these lesions in the chicken
Mycobacterium avium subspecies avium- poultry TB
60
What is the causative agent for feline leprosy
Mycobacterium lepraemurium
61
What are the clinical signs of feline leprosy
SQ lesions, freely movable lesions, tend to ulcerate, small acid fast bacilli
62
What is tx for feline leprosy
Surgical excision
63
From cat, what dz and what caused it
Feline leprosy caused by mycobacterium lepraemurium
64
what is answer in photo
Ziehl-Neelsen stain
65
What is answer
Inhalation of aerosols
66
What is answer
Mycobacteria prevents phagosome-lysosome fusion
67
What is answer
Erythrocytes
68
What is answer
skin test
69
what is answer
Mycobacterium avium subspecies paratuberculosis
70
What is the answer
profuse diarrhea

Microbiology (31 decks)

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