Differential Staining - Capsule, Spore, Gram, & Acid Fast - Deck (Practical) Flashcards
What is the difference between simple and differential staining?
Simple staining observes morphology while differential staining differentiates bacteria group (gram-positive or negative) and can identify structure
What 2 structures do differential staining focus on?
Capsule & spore
List 3 functions of the bacterial capsule.
1) Making bacteria more pathogenic
2) Protection from dessication
3) Attachment
What is the general principle behind capsule staining?
Capsules cannot be stained by the common dye
Capsule staining is a combination of { } & { } staining.
1) Negative
2) Positive (simple)
What forms the halo in a capsule stain?
The negative stain in the background and the positive stain in the cell
What are the 4 steps of capsule staining (HINT: NACroW)?
1) Preparing negative (primary) stained smear with nigrosine
2) Air dry
3) Counter-stain (positive dye - crystal violet)
4) Wash with water
Spore-forming bacteria are more resistant to { } and are more { }.
1) Sterilization
2) Pathogenic
What is the difference between the endospore and exospore?
The endospore is the spore developed inside the cell while the exospore is released after complete development
What are the 3 endospore positions?
1) Central
2) Terminal
3) Sub-terminal
What is the common method for spore staining (HINT: 4 steps)?
1) Primary staining of heat-fixed smear w/ malachite green & steam
2) Cool slide
3) Wash w/ water
4) Counterstain w/ basic dye (safranin)
Why can’t capsule staining slides be heat-fixed?
Heat shrinks the capsule
Which 2 differential staining methods help identify bacteria?
Gram & acid-fast
Gram staining - CrIES
Crystal violet (60 s)
Iodine (30 s)
Ethanol (5 s)
Safranin (30 s)
What is the principle behind gram staining?
Cell wall (structure and composition) differs between gram-positive and gram-negative bacteria
