AFB Practical #1 Flashcards Preview

Liz's Microbiology Module 2 > AFB Practical #1 > Flashcards

Flashcards in AFB Practical #1 Deck (41):
1

What species of mycobacteria are nucleic acid probes available for?

- M. tuberculosis complex
- M. avium complex
- M. gordonae
- M. kansasii

2

List 3 characeristics of Nocardia sp.

- Often appear powdery white due to production of aerial hyphae
- Branching GPR
- Partially acid fast

3

Nocardia sp.
- Modified acid-fast stain
- Kinyoun acid-fast stain

- Modified acid-fast stain positive (red)
- Kinyoun acid-fast stain negative (blue)

4

What is a confirmation test for M. tuberculosis and M. bovis?

Nitrate test
- M. tuberculosis (+)
- M. bovis (-)

5

What reagent must be added to a negative nitrate test? Why?

Addition of zinc dust confirms nitrogen gas

6

Niacin accumulation test is used to differentiate b/w which two mycobacterial species?

- M. tuberculosis (+)
- M. bovis (-)

7

Name 4 characteristics of M. mucogenicum

- Rapid grower
- Partially acid-fast
- Nonchromogen
- Wet/mucoid looking colonies

8

How is Kinyoun stain interpreted?

- Pos: red
- Neg: blue/purple

9

Known as the "cold" carbolfuschin-based stain

Kinyoun

10

The phenomenon known as cording is observed in which mycobacterium species?

M. tuberculosis (virulent factor)

11

Name 3 characteristics of M. marinum

- Grows at 28C
- Cutaneous infection associated w/ fish tanks or salt water
- Photochromogen

12

What type of stain is the auramine-rhodamine (AR) stain?

Fluorochrome stain

13

What are the advantages fo the AR stain?

- Most sensitive stain
- Stains both viable and nonviable organisms
- Performed directly on specimens

14

What are the disadvantages of the AR stain?

Won't stain rapid growers

15

What reagents are used in the N-acetyl-L-cysteine method of decontamination?

- N-acetyl-L-cysteine
- NaOH
- Sodium citrate
- Neutralizing buffer
- Phenol red

16

N-acetyl-L-cysteine
- Purpose of N-acetyl-L-cysteine

Works as a mucolytic agent

17

N-acetyl-L-cysteine
- Function of NaOH

Functions as a bacterial decontaminant

18

N-acetyl-L-cysteine
- Function of sodium citrate

Binds to heavy metals in the specimen

19

N-acetyl-L-cysteine
- Function of neutralizing buffer

Stabilizes the pH and stops the decontamination process

20

N-acetyl-L-cysteine
- Function of phenol red

Present in the digestion solution to monitor pH

21

Incubation requirements for MAC w/o crystal violet

Ambient air @ 28-30°C for 7 days

22

Which two mycobacterial species is the sodium chloride tolerance test useful in identifying? Results?

- M. abscessus (+)
- M. chelonae (-)

23

Incubation requirements for the Tween 80 hydrolysis test

Ambient air @ 35-37°C for 10 days

24

How is the Tween 80 hydrolysis test interpreted?

- Pos: pink/red
- Neg: orange/no color change

25

What is HPLC and how do we use it in the lab?

High performance liquid chromatography; provides an ID based on mycolic acid pattern, analysis of mycolic acids contained within mycobacterial cell walls

26

How do mycobacteria typically appear in gram stains?

Beaded or ghosted GPR (can look similar to strep)

27

Name 3 characteristics of M. gordonae

- Found in tap water
- Scotochromogen
- Non-pathogenic

28

Name 3 characteristics of M. tuberculosis

- Rough and buff
- Slow grower
- Nonchromagen
- Must confirm ID using biochemical methods

29

Which mycobacteria species deomonstrates candycane striations?

M. kansasii

30

Requires heme to grow, optimal temperature is 30C generally isolated from immunocomposed individualsq

M. haemophilum

31

What is the MB bottle (Myco F Lytic) used for?

Liquid medium used for blood, put into Bactec Fx, has heme (CHOC) in media to break apart RBCs to release organism

32

What is the MP bottle (MGIT) used for?

Liquid medium used for all specimen excepts blood; put into MGIT instrument, clear if uninooulated

33

Name 2 characteristics of M. kansasii

- "Candy cane" striations
- Photochromogen

34

What is the 7H10 slant used for?

All purpose, enriched for AFB, clear agar, if from a superficial source a second slant is set up and incubated at 30°C

35

Purpose of the choclate slant?

Used for specimens rich in heme (BM, blood), incubated at 30C

36

Purpose of LJ slant?

Lowenstein-Jensen, used in biochemical testing

37

Function of the 7H10 plate?

Used when isolation of colonies is desired

38

What PPE is used in the AFB lab

- Gloves
- Gown
- Mask (N95 or better)
- Foot covers

39

What unique characteristic is seen in M. szulgai?

Colonies are either smooth or rough

40

What is he media used in the 5% NaCl tolerance test?

LJ slant with 5% NaCl

41

What are the incubation requirements for the 5% NaCl tolerance test?

Incubated at 35-37C in CO2 up to 4 weeks