Smears & Stains
Simple Stains
enables us to visualize the shape and arrangement of bacteria cells by providing contrast
Wet Mount: of limited usefullness,not much to see when dealing with bacteria
Basic Stain: most common stains the cell, can apply + charged stain to negatively charged cell
Negative (acidic) Stain: stains the background, of limited usefulness
Differential Stains
in addition to shape and arrangement, tells us more
Gram Stain: Determining which type of cell wall, either G+ or G-
Acid-Fast Stain: Whether the organism belongs to a certain genera of medical importance (also cell wall stain) (waxy cell wall???) (mycobacterium like Tuberculosis, leprae)
The Question: What kind of cell wall does this organism have?
The Procedure:
1) Primary Stain - Crystal Violet
2) Apply a mordant - Iodine
3) Decolorize - w/ Alcohol or Acetone-alcohol, Differential Step
4) Counterstain - Safranin (Pink)
The Question: Does this organism have the waxy cell wall of mycobacterium?
The Procedure:
1) Primary Stain - Carbol Fuchsia
2) Heat - forcing stain inside the waxy cell wall
3) Decolorize - Acid Alcohol
4) CounterStain - Methylene Blue
The Results:
Acid-Fast: Fuchsia colored
Non-Acid-Fast: Blue
The Results:
G+: Violet
G-: Pink
Special Stains
Indicate the presence or absence of specific structures
Flagella Stain: Able to visualize the thin projections found on some organisms that are called flagella
Endospore Stain: Able to determine whether endospores are present in the sample
Capsule Stain: Able to visualize the capsules that some disease causing organisms have