general gut microbiology and mycobacteria SDL

Question 1

what is the main species affected by M tuberculosis

Answer 1

cattle

Question 2

what is the main type of infection caused by M. tuberculosis

Answer 2

• pulmonary tuberculosis
• extrapulmonary tuberculosis = migration from lungs to other areas (lymph nodes, bones and joints, CNS, genitourinary system, peritoneum)

Question 3

what body systems do M.avium affect

Answer 3

• respiratory
• lymphatic
• digestive
• musculoskeletal
• CNS
• skin
• repro

Question 4

which staining methods do you use to differentiate mycobacteria from other bacteria

Answer 4

Ziehl-Neelsen Stain

Question 5

what is the basis of Ziehl-Neelsen Stain on mycobacteria compared to other bacteria? what steps are in the method

Answer 5

Basis of Ziehl-Neelsen Stain:
Mycolic Acids: The high lipid content and mycolic acids in the cell walls of mycobacteria make them resistant to decolorization by acid-alcohol.
Dye Retention: Carbol fuchsin, a phenolic compound, can penetrate the waxy cell wall and bind tightly to the mycobacteria.
Acid-Fastness: Upon exposure to acid-alcohol, mycobacteria retain the carbol fuchsin dye, whereas other bacteria do not and become decolorized.
Steps in the Ziehl-Neelsen Stain Method:
Preparation:

Prepare a bacterial smear on a microscope slide and allow it to air dry.
Heat-fix the smear by passing the slide through a flame.
Primary Staining:

Flood the slide with carbol fuchsin stain.
Heat the slide gently until steam is visible, taking care not to boil or dry the stain (typically done for 3-5 minutes).
Alternatively, keep the slide on a heating block or use a Bunsen burner to maintain the heat. Ensure the stain remains moist by adding more carbol fuchsin if needed.
Cooling:

Allow the slide to cool for a few minutes to prevent rapid decolorization.
Decolorization:

Wash the slide with water to remove excess stain.
Decolorize the smear with acid-alcohol (a mixture of hydrochloric acid and ethanol) for about 1-2 minutes or until the runoff is clear.
Rinse the slide with water to stop the decolorization process.
Counterstaining:

Apply a counterstain, such as methylene blue or brilliant green, to the slide for 1-2 minutes.
Rinse the slide with water to remove the counterstain.
Drying and Examination:

Blot the slide gently with absorbent paper to dry it.
Examine the slide under a microscope using an oil immersion lens.

Question 6

how long does mycobacterium take to grow

Answer 6

1-6 weeks depending on species

Question 7

what is johnes disease

Answer 7

chronic, often fatal disease effecting the small intestines of ruminants

Question 8

what are the clinical signs of johnes disease

Answer 8

weight loss and diarrhea with normal appetite. Several weeks after the onset of diarrhea, a soft swelling may occur under the jaw. This intermandibular edema, or “bottle jaw,” is due to protein loss from the bloodstream into the digestive tract

Question 9

what are the clinical characteristics of Johne’s disease

Answer 9

• marked thickening of the gut wall
• ## profound hypoalbuminaemia and a normal globulin concentration

Question 10

are the clinical signs and impact of Johne’s disease the same in other species

Answer 10

• sheep will get poor fleece quality
• deer get poor antler growth
• cattle get more pronounced swellings

Question 11

which cells does mycobacterium avium subspecies paratuberculosis invade through

Answer 11

M cells in peyers patches

Question 12

which cell type do mycobacterium avium paratuberculosis reside in during infection

Answer 12

macrophages

Question 13

what is meant by granulomatous response in johnes disease

Answer 13

macrophages infected by MAP get activated and form granulomas

Question 14

although there is no proven zoonotic risk of Johnes disease, what human disease is often discussed as to whether there is a link to the same bacteria

Answer 14

crohns disease