AFB reactions and other info

Question 1

what are three identifying reactions of M. tuberculosis?

Answer 1

NAP (p-nitro-alpha-acetylamino-beta-hydroxypropiophenone) positive

68ºC catalase negative

niacin and nitrate positive

Question 2

what does M. tuberculosis look like on media?

Answer 2

slow growing, rough, dry, granular, and buff colonies

AFB: cording

Question 3

what is M. bovis (small, granular, rounded, white colonies) sensitive/susceptible to?

Answer 3

thiophen-2-carboxylic acid hydrazine (TCH)

Question 4

testing-wise, how would you tell the photochromogens apart?

Answer 4

M. kanasii is nitrate positive (and also SQ cat >45 mm)

M. marinum is
- nitrite negative
- SQ catalase less than 45 mm
- grows at 30ºC

Question 5

testing-wise, how would you tell the scotochromogens apart?

Answer 5

M. gordonae is nitrate neg and tween 80 pos while M. scrofulaceum is nitrate neg but also tween 80 neg

Question 6

M. avium is _______ ________ _______ (compared to the other nonchromogens)

Answer 6

relatively inactive biochemically

Question 7

What differs M. xenopi from the nonchromogens?

Answer 7

optimal temp is 42ºC and has a bird’s nest colony morphology

Question 8

M. haemophilum grows at what temp? what three things does it need?

Answer 8

grows at 30ºC

needs
- hemin
- hemoglobin
- ferric ammonium citrate

Question 9

M. ulcerans grows at what temp?

Answer 9

30º C

Question 10

how do you tell the fast grower AFBs apart, testing-wise?

Answer 10

1. M. fortuitum
   - both nitrate and iron uptake positive
2. M. chelonae
   - nitrate, iron uptake, AND 5% NaCL negative
3. M. abscessus
   - both nitrate and iron uptake neg, but 5% NaCL positive

Question 11

what two testing characteristics do all M. fortuitum complex spp. have in common?

Answer 11

• arylsulfatase pos
• special MacConkey pos