Mycobacteriology Practical Flashcards
What are the characteristics of M. Haemophilium?
Requires Heme, optimal @30 degrees, isolated from immunocompromised
What nucleic acid probes are available?
MTB complex, M.avium-intracellulare complex, M. gordonae, and M kansasii
What are the characteristics of Nocardia sp.?
Appear powdery white due to aerial hyphae, Branching GPR, Partial acid fast
What is a mycobacterium that never produces pigment?
Nochromogen
What is mycobacterium that produces pigment after light exposure?
Photochromogen
What is a mycobacterium that produces pigment independently of light exposure?
Scotochromogen
What are nitrate test results for MTB and M bovis? What is added to a negative result?
MTB is pos (red)
Bovis is neg (no color change) Zinc dust is added to confirm test worked
What are niacin test results for MTB and M. Bovis?
MTB is pos (yellow), M. Bovis is neg (no color change)
What are characteristics of M. mucogenicum?
Rapid grower, wet colonies, Partially acid fast, nonchromogen
How is Kinyoun stain interpreted?
Red is pos, Blue is neg
What are the characteristics of Kinyoun stain?
Cold stain, Carbolfuchsin based, sold or liquid growth used
What mycobacterium demonstrates cording? What is it associated with?
MTB, virulence
What are the characteristics of M. marine?
Grows @28, skin infection with fish tanks or salt water, Photochromogen
What type of stain is Auramin-Rhodamine stain (AR said). What are its advantages and disadvantages?
Fluorochrome stain, performed directly on specimens
Ad=Most sensitive stain in AFB, Stains both viable and nonviable
Dis=Wont stain some rapid
What is the function of N-acetyl-L-cysteine?
mucolytic agent, frees organisms
What is the function of 2% NaOH?
Decontaminant to 5%
What is the process of the N-acetyl-L-cysteine decontamination?
Sodium citrate binds to heavy metals, neutralizing buffer stops decontamination process, Phenol red indicates pH
What are the incubation requirements for MAC w/o CV? How are results interpreted?
Ambient air, 28-30 for 7 days, used to ID rapid growers
Neg=no growth/scant growth POS is growth to end of line
What does the NaCl tolerance test differentiate?
M. abscesses( >50 colonies= +) and M. Chelonae (
What medium is used with the NaCl test and how is it incubated?
LJ with 5% NaCl, .1ml or light suspension @35-37 in CO2 for 4 weeks
What are the incubation requirements for the tween-80 test? How are results interpreted?
35-37 ambient air for 10 days, Pink/red= nonpathogens=(+ result) No color change = pathogenic= (neg result)
What does HPLC stand for? What is it used for?
High performance liquid chromatography, used to differentiate rapid growers based on mycelia acid contained in cell wall.
What does a gram stain of mycobacteria look like?
Beaded or ghosted GPR, confused with strep
What are the characteristics of Mycobacterium gordonae?
Commonly found in tap water, contaminate in lab, Scotochromogen
What are the characteristics of MTB?
Rough and Buff, slow grower, nonchromogen, Prob available but only for complex ID with Niacin
What are the characteristics of M. kansasii?
Probe, Photchromogen, candy cane striations
What are the 6 media used in AFB lab? What do they ID?
MB bottle: Liquid for blood; BacT alert
MP Bottle: Liquid for all but blood; BacT alert
7H10 slant: Enriched Soild for all skin = incubate @30 too
Chocolate: for those that require heme @30
LJ: Biochemical testing
7H10 Plate: when isolation required
What are the PPE in AFB lab?
Floves, impervious down, N95 or greater mask, foot covers
All checked at least once a year
What are the characteristics of M. szulgai?
Scotochromogen @37, Photchromogen @25, nitrate positive, colonies either smooth or rough
