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