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UND 363 Kinyoun AFB
UND 363 Kinyoun Acid Fast
Question | Answer |
---|---|
purpose for Kinyoun Acid Fast (A/F)stain | demo of acid fast mycobacteria |
principle | lipoid capsule of A/F mycobacteria takes up carbol fuchsin and resists decolorization with dilute mineral ACID. |
what is carbol fuchsin more soluble in (lipids of cell wall or acid-alcohol) and how does this affect NON A/F bacteria | it is more soluble in the lipids of the cell wall. NON A/F bacteria lack the waxy capsule and therefore carbol-fuchsin is easily removed |
what does the Phenol and alchol in this stain do? | they aid in dissolving the basic fuchsin |
Why is heat necessary (Vs. room temp) for this technique | lipoid capsule is waxy at room temp, the heat allows the dye to penetrate into the bacteria |
fix for Kinyoun Acid Fast stain | NBF preferred, others can be used EXCEPT CARNOYS WHICH CANNOT BE USED BECAUSE IT WILL CAUSE A/F BACTERIA TO BECOME NON A/F |
what does Carnoys fixative do to A/F bacteria | It will make them NON A/F |
microns | 4-5 |
Qc | tissue with A/F organisms, must use Millipore filtered (.45 micron pore size) water, and a negative control from same day workload. |
why can tap or distilled water NOT BE USED before the carbol-fuchsin step | there may be bacteria in the piping |
Reagents in order for Kinyoun Acid Fast stain | Millipore water, kinyoun carbol fuchsin (basic fuchsin/phenol crystal/alcol), HCL/alcohol - diff'r, methylene blue - counterstain |
in the Kinyoun carbol fuchsin what does the carbol fuchsin do? what about the Phenol/alcohol? | C.F. stains the lipid capsule, the phenol and alshol enhances staining and aids in dissolving of the stain. |
results for Kinyoun Acid Fast stain | A/F bacteria - bright red, background - blue |
what must be done after the adic alcohol step (hcl/alcohol) | must be rinsed well before counterstaining or the tissue will not stain |
why can the sections not be allowed to dry out after carbol fuchsin | a compound that resists decolorization will form |
what helps the penetration of phenol (AKA carbolic acid) in this stain | heat and the action of wetting agents (which reduce surface tension and enhance spread of phenol) |
if overstained with methylene blue what will occur and what can be done | it will mask any organisms present. Fix - take slide back to acid alcohol (step 4) to remove methylene blue, wash with water and repeat counterstain |
what can kinyoun A/F not be used for and why | mycrobacterium leprae (Must use the FITE stain instead). This bacteria is sensitive to alcohols. |