Acid Fast Stain

Question 0

TSI Test Result: what do these colors of tube mean?

• yellow
• pink red
• black

Answer 0

• entire tube is “Yellow”, Bac fermented the glucose ( yellow buttom) and at least one of the other sugars,sucrose or lactose or both ( yellow slant). (Bac eat all 3 sugars).
• Pink red, Bac can only eat glucose, but not others 2 sugars. It has to break down peptones to produce ammonia. Then convert the pH
  To alkaline and turns the agar pink red.
• H2S is produced, black color is observe b/c Bac fermented glucose( yellow butt), but also used peptones( pink red slant)

Question 1

Triple Sugar Iron:

• contains how many carbohydrates?
• what is the indicator? Its goal?
• what does Yellow color indicate? Red pink color?

Answer 1

• this medium contains 3 carbohydrates and differentiates Bac on fermentation of glucose, sucrose and lactose.
• The indicator is phenol red. To monitor the pH.
• Yellow in acid pH. Pink red in alkaline pH

Question 2

TSI Test:

- hoe to know the presence of “Gas” in tube?

Answer 2

• bubbles, cracks or agar up the tip.

- Breaks or air space in agar

Question 3

SIM Test:
- what happen when adding Kovac's agent to SIM tube with Indole?
- motility : black? Yellow?
UREA Test:
Pink
Peach

Answer 3

-Tube: Kovac’s + Indole = turns cherry red! indicating the presence of “Rosindole”.
- Black (motile) and Yellow (non- motile).
Urea test:
Pink red:positive
Peach: negative

Question 4

What is the Acid Fast Stain used for?

Answer 4

• It is a differential stain that detects the presence or absence of my colic acid.

Question 5

What is a mycolic acid?

Answer 5

Mycolic acid is a waxy hydrocarbon over 80 *C in length

Question 6

• Mycolic acid is sometimes referred to what?

- What is mycolic acid % of dry weight of the mycobacterium?

Answer 6

• Cord Factor which results in clumping and aggregating of Bac cells.
• 50%

Question 7

What is the primary dye of a phenolic compound?

Answer 7

A phenolic compound uses “carbolfuchsin” as a primary dye which is a lipid soluble, concentrated stain.

Question 8

Why is phenolic acid used for?

Answer 8

Phenolic acid allows to penetrate the huge carbohydrate.

Question 9

What is the role of mycolic acid?

Answer 9

It gives lipids a higher affinity for carbolfuchsin

Resists decolonization with acid alcohol.

Question 10

If Bac have mycolic acid, it turns into what color? If not? What color

Answer 10

• (+) pink / red : presence of mycolic acid ( fast acid mycobacterium)
• (-) blue: no presence of mycolic acid ( staphylococcus). Bac that r not acid fast are easy to decolorized by acid fast decolonization step and stain with the counterstain methylene blue.

Question 11

What Bac causes tuberculosis ? Leprosy?

Answer 11

• Mycobacterium tuberculosis. 1/3 population of earth infected
• Mycobacterium leprae.

Question 12

Procedure:

Agar plate culture of mycobacterium smegmatis ans staphylococcus aureus.

Answer 12

• Drop the circle on the slide and add a drop of Saline to the center
• Flame a loop and let it cool
• Take a small amt of a mycobacterium and spread out in to the saline. Flame the loop.
• in the same smear, mix a small amt of staphylococcus with sterile loop. Flame the loop n return it.
• let it air dry or dry above the incinerator.
• cover the smear area with carbolfuchsin for 5 min
• wash with distille water
• Decolorize with the acid alcohol for 5 sec
• immediately add water to stop decolonization
• Add methelyne blue counterstain for 30 sec
• wash the counterstain off
• Dry the slide with bibulous paper.
• Observe under oil immersion.

Question 13

Acid fast mycobacterium will appear? Staphylococcus?

Answer 13

Pink

Light blue