Exam 3: Mycobacteria

Question 1

What is mycobacteria loosely classified by?

Answer 1

Mycobacterium tuberculosis complex

Question 2

What makes up the mycobacterium tuberculosis complex?

Answer 2

M. tuberculosis
M. bovis
M. africanum
M. microti

Question 3

What is non-tuberculos mycobacteria further classification based on?

Answer 3

Growth rate and pigment production (Runyon group)

Question 4

What does M. scrofulaceum cause?

Answer 4

Tuberculosis lesion

Question 5

What does M. avium cause?

Answer 5

Avian tuberculosis

Question 6

What does M. intracellulare cause?

Answer 6

Avian tuberculosis

Question 7

What are the general characteristics of mycobacteria?

Answer 7

Obligate aerobic
Non-spore forming
Non-motile

Question 8

What does the growth of mycobacteria require?

Answer 8

Complex egg-enriched media, such as Dorset’s egg medium, Lowenstein-Jensen agar, or Herrold’s egg yolk agar medium

Question 9

What does mycobacteria make a living in?

Answer 9

Macrophage: intracellular parasite

Question 10

What do you need to stain mycobacteria? Why?

Answer 10

Acid fast stain because of mycolic acid and WaxD

Question 11

What does the cell wall of mycobacteria consist of?

Answer 11

Mycolic acid
Cord factor (lipoarabinomannan, generated from trehalose dimycolate)
WaxD (peptidoglycan)

Question 12

What is the tubercle bacilli recognized in humans?

Answer 12

M. tuberculosis

Question 13

What is the tubercle bacilli recognized in bovine?

Answer 13

M. bovis

Question 14

What is the tubercle bacilli recognized in avian?

Answer 14

M. avium complex (M. avium, M. intracellulare, and M. scrofulaceum)

Question 15

Can the 3 tubercle bacilli species cause disease only in the species they are recognized in or can they produce infection in host species other than their own?

Answer 15

They can produce infection in host species other than their own

Question 16

What is M. bovis a major cause of?

Answer 16

Human TB before the eradication program implemented in 1924

Question 17

What reduced M. bovis infection from 5% in 1917 to less than 0.001% currently?

Answer 17

Milk pasteurization and slaughtering all tuberculin skin test positive animals

Question 18

What is the attenuated live M. bovis vaccine used?

Answer 18

Bacillus Calmette-Guerin (BCG)

Question 19

Can the BCG vaccine be used in the US?

Answer 19

No, federal law prohibits it

Question 20

What happens to inhaled bacilli of M. bovis?

Answer 20

Phagoctyosed by alveolar macrophages that allow thee mycobacteria to proliferate

Question 21

What is formed when the mycobacteria proliferate?

Answer 21

Primary focus

Question 22

How is the classic tubercle formed from a M. bovis infection?

Answer 22

Purulent to caseous, necrotic center may calcify, and the lesion may become surrounded by granulation tissue and a fibrous capsule to form the classic tubercle

Question 23

Describe the immunity associated with M. bovis

Answer 23

Cell-mediated immunity, delayed-type hypersensitivity

Question 24

When are clinical signs of a M. bovis infection evident?

Answer 24

In advanced disease

Question 25

What is used for antemortem diagnosis of M. bovis

Answer 25

The intradermal tuberculin tests

Question 26

What is the intradermal tuberculin tests based on?

Answer 26

Delayed-type hypersensitivity

Question 27

What are the official tuberculosis tests approved by the USDA?

Answer 27

Caudal fold tuberculin (CFT) test Cervical tuberculin (CT) test Comparative cervical tuberculin (CCT) test Bovine interferon gamma assay (cattle only)

Question 28

When are CCT injections given?

Answer 28

Within 10 days following CFT injection or more than 60 days following CFT injection

Question 29

When must blood samples be collected for bovine interferon gamma assay?

Answer 29

Between 3 and 30 days after injection of bovine tuberculin

Question 30

What does the media contain that grows M. lepraemurium?

Answer 30

Cytochrome C and α-ketoglutarate

Question 31

What is M. leprae the cause of?

Answer 31

Leprosy in humans

Question 32

What has M. leprae been found in?

Answer 32

Spontaneously occurring disease in armadillos

Question 33

Describe M. avium infection

Answer 33

Ubiquitous in the environment Produces disease primarily in birds Birds are natural host Serotypes 1, 2, and 3 are usually more virulent in birds

Question 34

What is M. avium subs. paratuberculosis a causative agent of?

Answer 34

Johne's Disease

Question 35

What does M. avium subs. paratuberculosis form rough colonies on?

Answer 35

Middlebrook agar medium

Question 36

What does in vitro growth of M. avium subs. paratuberculosis require?

Answer 36

An iron-transport compound known as mycobatin J

Question 37

What is M. avium subs. paratuberculosis capable of even though it is not able to grow and multiply in the environment?

Answer 37

It is extremely hardy and may remain in contaminated soil and water for a year or ore by developing extra tough outer coat (mycolic acid)

Question 38

What is the primary transmission route of M. avium subs. paratuberculosis?

Answer 38

Fecal-oral infection

Question 39

What is the primary site of infection for M. avium subs. paratuberculosis?

Answer 39

Ileum

Question 40

How does M. avium subs. paratuberculosis invade?

Answer 40

Through specialized ileal tissue called Peyer's Patches via M cell to immune cell (macrophage)

Question 41

What are clinical symptoms of M. avium subs. paratuberculosis?

Answer 41

Persistent diarrhea and weight loss

Question 42

How is M. avium subs. paratuberculosis diagnosed?

Answer 42

By testing an adult animal

Question 43

What are the diagnostic tests available for M. avium subs. paratuberculosis that are approved by the USDA?

Answer 43

Fecal culture ELISA Gene probe/PCR test

Question 44

Is there treatment for Johne's?

Answer 44

No

Question 45

Should a vaccine be used against M. avium subs. paratuberculosis?

Answer 45

No

Question 46

What is being done for control and eradication of M. avium subs. paratuberculosis?

Answer 46

USDA sponsored voluntary eradication program