Mycobacteria Seo

Question 1

Mycobacterium tuberculosis (TB) complex

Answer 1

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

Question 2

Non-tuberculos Mycobacterium

Answer 2

further classified based on growth rate and pigment production (Runyon Group)

Question 3

Mycobacterium general characteristics

Answer 3

Obligate aerobe
The growth requires complex egg-enriched media such as Dorset’s egg medium, Lowenstein-Jensen agar, or Herrold’s egg yolk agar medium
Makes a living in macrophage: intracellular parasite

Question 4

Mycobacterium general characteristics continued

Answer 4

acid-fast stain because of mycolic acid and WaxD
Cell wall consists of mycolic acid, cord factor (lipoarabinomannan, generated from trehalose dimycolate), and waxD (peptidoglycolipid)

Question 5

M. tuberculosis, M. bovis, and M. avvium complex infect….

Answer 5

Normally, humans, bovine, and avian, but they may also produce infection in host species other then their own

Question 6

M. bovis infection (eradication)

Answer 6

A major cause of human TB before eradication program implemented in 1924
Milk pasteurization and slaughtering all tuberculin skin test positive animal reduced M. bovis infection from 5% in 1917 to less than 0.001% in current

Question 7

M. bovis vaccine

Answer 7

Attenuated live M. bovis used as a vaccine: Bacillus Calmette-Guerin (BCG)
Federal law prohibits the use of BCG vaccine in the United States

Question 8

M. Bovis pathogenesis

Answer 8

• Inhaled bacilli are phagocytosed by alveolar macrophages that must clear the infection or allow the mycobacteria to proliferate
• May form a primary focus
• The 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 9

M.bovis aerosol

Answer 9

• Recognizable tubercle formed
• Delayed type hypersensitivity (30 days)
• Leads to effective cell-mediated immunity

Question 10

M. Bovis clinical findings

Answer 10

clinical signs are only evident in advanced disease

Question 11

M. bovis diagnostics

Answer 11

• The intradermal tubculin tests

- based on delayed-type hypersensitivity

Question 12

Official tuberculosis test

Answer 12

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

Question 13

M. lepraemurium infection

Answer 13

May be grown on media containing cytochrome C and alpha ketoglutarate

Question 14

M. leprae infection

Answer 14

• cause of leprosy in humans

- spontaneously occurring disease in armadillos

Question 15

M. avium infection

Answer 15

• Ubiquitous in the environment
• Produces disease primarily in birds
• birds are natural host

Question 16

M. avium subspecies paratuberculosis (MAP) infection

Answer 16

• a causative agent of John’s (Yo-Nees” disease
• forms rough colonies on Middlebrook agar medium
• In vitro growth requires an iron-transport compound known as mycobatin J
• MAP is extreamely hardy and may remain in contaminated soil and water for a year or more by developing extra tough outer coat (mycolic acid

Question 17

M. avium subspecies paratuberculosis (MAP) pathogenesis

Answer 17

• transmission through fecal-oral infection
• infects the ileum
• Invades through specialized ileal tissue called Peyer’s patches via M cell to immune cell (macrophage)
• diarrhea and weight loss

Question 18

M. avium subspecies paratuberculosis (MAP) diagnosis

Answer 18

• Test adult animal (at least 18 month old)

- Fecal culture: any species; approved by USDA

Question 19

M. avium subspecies paratuberculosis (MAP) diagnosis continued

Answer 19

• ELISA: approved by USDA

- Gene probe/PCR test: approved by USDA

Question 20

M. avium subspecies paratuberculosis (MAP) treatment and prevention

Answer 20

• Currently no treatment for John’s disease
• Vaccine is not the solution
• Control and eradication: USDA sponsored Voluntary eradication program is implemented