Mycobacterium

Question 1

What type of mycobacteria have the shortest chains? Longest chains?

Answer 1

rapid growing have shortest chains
slow growing have longest chains
Corynebacterium

Question 2

Properties attributed to Mycoli Acid in Mycobacteria

Answer 2

acid fast positive
drug, chemical, and enviromental resistance
immunomodulating activities
prevent phagocytic killing

Question 3

Describe Acid Fast staining and the steps involved with it

Answer 3

differential stain that uses lipid permeabilizing first step (with heat or chemical solvent)
1. primary stain
2. acidic alcohol decolorizing step
3 counter stain
ex: Carbol fuschin>decolorizer>methylene blue

Question 4

Examples of acid fast stains

Answer 4

Ziehl-neelsen
Kinyons
Auramin rhodamine (flurescent, very sensitive)

Question 5

Habitat of Mycobacterium spp

Answer 5

Some obligate pathogens
some oppourtunistic
many soil/water saprophytes

Question 6

How are mycobacterium classified?

Answer 6

By how fast they grow and how they grow in light

Question 7

Mycobacterium Virulence Factors

Answer 7

Mycolic acid contains cell wall lipids

Cell protein antigens

Question 8

What is the function of mycolic acid?

Answer 8

To facilitate survival in MO
Stimulate cytokine production
Enhance adjuvant/immunomodulating effects

Question 9

What property of mycobacteria varies by genus?

Answer 9

Fatty acids in the cell wall- the carbon chain length varies by genus

Question 10

What spp cause Mammalian tuberculosis?

Answer 10

M. tuberculosis complex- M. tuberculosis, M. bovis, M. africanum, M. microti

Question 11

What spp cause Avian tuberculosis?

Answer 11

M avium subsp avium serotypes 1-3

Question 12

What causes Leprosy in humans? Cats?

Answer 12

M leprae humans

M lepraemurium cats

Question 13

What causes Johne’s dz?

Answer 13

M. avium subsp paratuberculosis

Question 14

What spp are the main resivours for M. tuberculosis?

Answer 14

Humans

Question 15

What other species can get M. tuberculosis?

Answer 15

dogs, cats, pigs, nonhuman primates
psittcine birds and canaries 
elephant to human transmission 
banded mongoose
suricates

Question 16

M tuberculosis is multidrug reistant (MDR) and extensively drug resistant (xdr) to which drugs?

Answer 16

MDR- isoniazid and rifampin

XDR- isoniazin and rifampin plus fluroquinolone and at least one of 3 inj second line drugs

Question 17

How does Mycobacterium bovis cause zoonotic TB?

Answer 17

ingestion, inhalation, sometimes contact with mm and broken skin

Question 18

What is the main portal of entry for M. bovis?

Answer 18

GI tract

Question 19

In what species is M. bovis primarily maintained in?

Answer 19

Bovine

Question 20

What mycobacterium has the broadest host range and infects cervids?

Answer 20

M. bovis

Question 21

t/f M. bovis causes dz indistinguishable from that of M. tuberculosis in humans?

Answer 21

T

Question 22

Other resirvoirs of M. bovis in the UK and New Zealand?

Answer 22

Badgers in UK

Brush tail possums- New Zealand

Question 23

M bovis infection (describe)

Answer 23

Can be chronic, progressive or latent
usually subclinical, found at slaughter
Some animals will never get progressive dz

Question 24

M. bovis transmission

Answer 24

Aerosol most common
Shed in milk (pasteurize to kill)
Can enter body at any site

Question 25

M. bovis Clinical Signs

Answer 25

varies enlarged regional LN, cachexia coughing w/ pulmonary form

Question 26

M. bovis pathology

Answer 26

Can causes lesions in any organ early- lesions are hard to find, some look like abcesses later- firm nodular lesions in target organs and associated LN (lungs, head, GI) Main lesion: granuloma

Question 27

Pathogenesis of M. bovis

Answer 27

Bacilli are either phagocytosed and destroyed via cell mediated immunity or survive leading to type I hypersensitivity causing caseous necrosis liquefaction and cavity formation result from enzymatic action and rupture of the cavaties allows dissemination

Question 28

What are the lesions associated with tuberculosis?

Answer 28

Tubercles/Granulomas Soft- caseous necrosis Hard- well organized granulomas packed with epitheloid MO both are surrounded by multinucleated giant cells (langhan's cells)

Question 29

What the elements of a tubercle?

Answer 29

``` Granuloma formation as a result of cell mediated response activated MO/epitheloid cells caseous necrosis fibrosis mineralization or liquefaction ```

Question 30

What are dx tests for M. bovis?

Answer 30

Tuberculin hypersensitivity skin tests- PPD in caudal tail fold Comparative cervical tb skin test (compares bovine w/ avian PPD) In vitro whole blood tests for cell mediated immunity- IFN-y Post mortem xrays Acid fast staining of tissues Culture PCR

Question 31

What is a good culture medium for M. bovis?

Answer 31

Lowenstein Jensen | fatty acid enriched media for pathogenic species

Question 32

T/F You always use combination drug therapy to tx active TB

Answer 32

True

Question 33

How can you preven bovine tb?

Answer 33

``` dz surveillence pre and post movement cattle testing removal of cattle exposed to bTB tracing poteintail souce of infection wildlife control ```