Mycobacterium and Associated Diseases Flashcards
1
Q
What makes up the membrane of Mycobacterium?
A
- Mycolic acid
- Acyl lipid
- Lipoarbinomannan (LAM)
- Arabinogalactan
- Peptidoglycan porins and a lipid bilayer
2
Q
What are the general morphologic characteristics of Mycobacterium?
A
- Unique cell wall
- high lipid content
- Mycolic acids, complex waxes, unique glycolipids (up to 60% of the dry weight of the organism)
- high lipid content
- Rod shaped
- Non motile
- Over 100 species and subspecies
- non pathogenic
- obligate intracellular pathogens
- opportunistic pathogens
3
Q
What does the unique cell wall of Mycobacterium do?
A
- Ability to resist:
- Dehydration
- acid or alkali inactivation
- heat / cold
- several common antibiotics
- Common disinfectants
- Can survive in soil for up to a year
4
Q
How well do mycobacterium grow?
A
- Very slow
- slow doubling times 12 - 24 hours
- Colonies arise in 2-6 weeks or longer
- rapid growers in 48 - 72 hours
5
Q
What is the pathogenesis of Mycobacterium?
A
- Intracellular survival - most important virulence property
- Cellular antigen stimulate cell mediated and humoral immune responses
- immune response leads to granulomas
- Caseous necrosis at center of granulomas may lead to calcification or liquefaction
6
Q
How is Mycobacterium diagnosed?
A
- Direct examination of the organism after acid-fast staining
-
Tuberculin skin test
- determine delayed-type hypersensitivity reaction
- Culture
- Antibodies by Agar-gel immunodiffusion, ELISA, CF and IFA
- PCR
7
Q
Why does Acid-fast staining work with Mycobacterium?
A
- Complex cell wall retains carbol-fuchsin dye when decolorized with acid-alcohol
- Allows for differential staining
- other bacteria stain blue
8
Q
What diseases are cause by Mycobacterium?
A
- Johne’s disease - ruminants
- Crohn’s disease - humans (?)
- Pulmonary tuberculosis - humans & animals
- Hansen’s disease - humans (leprosy)
- Feline leprosy
- Avian tuberculosis
9
Q
What is the causative agent of Johne’s Disease?
A
Mycobacterium avium subspecies paratuberculosis
10
Q
What animals does Johne’s Disease affect?
A
- Cattle
- Sheep
- Goats
- Deer
- Antelope
- Llamas
11
Q
What are the symptoms of Johne’s Disease?
A
- Weight loss
- Diarrhea
- Bottle Jaw
- Submandibular Edema
12
Q
What is the pathogenesis of Johne’s Disease?
A
- Infection results in granuloma formation
- Thickens intestinal wall and impairs function
- Diarrhea, poor absorption of nutrients
- Animal eats but rapidly lose weight
13
Q
How is Johne’s Disease transmitted?
A
- Enters with healthy looking infected animal
- Spreads very slowly
- Infects very young animals
- contaminated feed
14
Q
How is Johne’s Disease controlled?
A
- Prevent indroduction of infected animals
- Raise newborns in clean environment fed milk free of M. paratuberculosis
- Identify and remove infected animals
- Infected herds tested yearly
- Cull positives
15
Q
What is the treatment for Johne’s Disease?
A
- Not curable by antibiotics
- Cost prohibitive
- Cull from herd
