Mycobacteriology Exam Flashcards
What organisms stain on acid fast?
Myvobacterium
What are the advantages of Carofuchsion and fluorescent stains?
CF: Stains all Fluor: More sensitive for MTB, easier to see fewer organisms.
What are the disadvantages of Carofuchsion and fluorescent stains?
CF: Less sensitive Fluor: Poor for rapid
Why do acid fast bacteria stain acid fast?
Cell wall rich in lipid which resists decolorization
What is a tuberculous granuloma?
Walling off = TB(+), Lymphs produce gamma interferon
Location of lung were types of TB (primary and secondary) are located.
Primary: Near middle of lung where air circulates Secondary: Near top of lung where oxygen is
Look at pie char for racial distribution
White: 16% Black: 25% Mexican: 29% Hawaii: 1% Asian: 28% Indian: 1%
US born
White: 32% Black: 42% Mexican: 19% Hawaii:
Where is the highest rate of TB found?
South & Southeast Asia
East Asia and Pacific
Sub-Saharan Africa
What are the 6 populations with increased MTB infections?
AIDS, Drugg users, Nursing homes, Homeless shelters, Immigrants
What are the sputum processing guidelines for ID of MTB?
Early morning, 3-5 specimens preferably 24hrs apart. REFRIGERATE.
Add N-acetyl L-cysteine (digestion=frees) and 2% NaOH. Vortex (decontamination) and sit 20 min.
Add phosphate buffer and centrifuge 3000-3800g Decant and add 2ml Phosphate buffer.
Screen for MTB with Fluorescent Acid fast
What are the methods for ID of M. Leprae?
There are not any Lab methods. (Dermatologist can Biopsy and acid fast to ID organisms if present)
What is the medium for MGIT, BacTALERT and BACTEC.
MiddleBrook broth
Define Rapid grower
Grow in
What is the most reliable biochemical test for ID of MTB?
Niacin
What is the least reliable Biochemical for ID of MTB?
Nitrate
What is a Phtochromogen?
Yellow w/ light
What is a Nonchromogen?
Never produces a pigment
What is a Scotochromogen?
Produces pigment independently of light exposure
Memorize the pathogenic M. species table on powerpoint 2 page 2, first slide.
This table is very important, I talked with Katie about tit and knowing it will be very useful
How do you ID MTB?
Niacin(+), = go to bank
Nitrate(+), T2H resistant, heat stable catalase(-) unless INH resistant
Why would RNA be used over DNA?
There is a lot more RNA than DNA.
What is an accuprobe and what does it target
RNA from MEDIA
What is a Cepheid (gene expert) and what does it target?
DNA directly from specimen
What are the advantages and disadvantages of amplified DNA
Uses clinical specimen so it is faster but it uses DNA which is not as sensitive
Runyon group 1
Photocromogens
Runyon group 2
Scotochromogens
Runyon group 3
Nonchromogens
Runyon group 4
Rapid Growers
What are the 3 members of MTB complex?
MTB, M. Bovis, M. africanum
What is the criteria for skin culturing?
37 AND 30-32 degrees
What bacteria is inhibited by T2H?
M. Bovis
What bacteria are nitrate pos?
MTB, M. kansasii, M. szulgai, M. fortuytum
How do pathogenic and nonpathogenic scotochromogens react in urease generally?
Urease neg scotochromogens are usually pathogens
Which test differentiate MTB and M. Bovis?
Niacin, T2H (nitrate)
What bacteria grows best less than 35-37?
M. marinum
What bacteria grows best at greater than 37?
M. xenopi
How does the TB process make positive testing results?
Macrophage is infected with TB, Lymphs surround and produce interferon gamma (=granuloma)
Gamma interferon is measured by ELISA, reliable on vaccinated individuals and AIDS
How is cord factor used to ID and what is its importance?
ID’s TB and increases its virulence
What are the special requirements of M. Haemophilum?
Needs heme
What is the appearance of MTB on agar plates?
Rough and buff
What is the appearance of M. kansasii on agar plates?
Produces pigment in light
What is the appearance of M. xenopi on agar plates?
Always produces pigment
What is the appearance of M. fortuitum on agar plates?
Rapid grower, may be rusty colored
Explain the following about M. bovis: how it affects the TB skin test, how it is used in cancer patients, how it is identified, and relationship to BCG
Gives (+) TB test, used in bladder caner patients, inhibited by T2H, attenuated strand for BCG vaccine
What are the two solid media used for isolation of mycobacterium?
Lowenstein Jensen (LJ) and Middlebrow 7H10
What are the 3 types of broth media for isolation?
Tactic-MGIT, Organon Teknika-BacAlert, and Bactec 9000
What media is used to ID organisms more quickly?
Broth
What temps are cultures set up at?
ALL @ 37, Skin @37 and 30-32
What media are all organisms set up in?
BOTH
What are the results of arylsylfatase nitrate, iron uptake and MAC for M. fortuitum?
arylsulfatase(+), nitrate(+), iron uptake(+), and MacConkey(+)
What are the results of arylsylfatase nitrate, iron uptake and MAC for M. chelonae?
arylsulfatase(+), nitrate(-), iron uptake(-), and MacConkey(-)
What are the results of arylsylfatase nitrate, iron uptake and MAC for M. abscesses?
arylsulfatase(+), nitrate(-), iron uptake(-), and MacConkey(+)
How is tween used to differentiate pathogenic and nonpathogenic scotochromogens?
Tween positive are usually nonpathogenic
What bacteria are nitrate pos?
M. tuberculosis, M. kansasii, M. szulgai, M. fortuitum
What bacteria are in scrofulous wounds in adults?
MTB
What bacteria are in scrofulous wounds in children?
M. scrofulaceum
What bacteria is historicaly associated with AIDS patients and isolated from their stools/blood?
M. avium
What characteristics are used to differentiate organisms into their runyon groups?
Pigment production and growth rate
What are the 4 probes for mycobacteria ID?
TB complex, Avium-intracellulare complex, M. gordonae, and M. Kansasii
Where is M. bovid typically found and how is it transmitted?
Cows, and transmitted by their products
What organisms and characteristics are IDed by the GENExpert?
MTB and Rifampin
What is the ideal contamination rate for specimens?
5%
What mycobacteria produces disease similar to MTB and is a photchromogen?
M. Kansasii
