Stains

Question 1

What is a Wet Mount?

Answer 1

• unstained specimen examined by brightfield, darkflield or phase-contract micrscopy

Question 2

10% KOH?

Answer 2

• potassium hydroxide used to dissolve proteinaceous elements and examine fungal elements that aren’t affected by strong alkali

Question 3

India Ink?

Answer 3

• contrast dye primarily used for cryptococcus in CSF, etc.

Question 4

Lugol Iodine?

Answer 4

• contrast dye used to detect internal stuctures of amobae and differentiate surrounding WBCs

Question 5

Iron Hematoxylin stain?

Answer 5

• used for ID of fecal protozoa

Question 6

Methenamine Silver?

Answer 6

• detection of fungal elements in tissue
• usually used in histology

Question 7

Toluidine blue O stain?

Answer 7

• used for detection of Pneumocystis in resp. specimens

Question 8

Trichrome stain?

Answer 8

• alternative to iron hematoxylin
• protozoa - green/blue cytoplasm, red/purple nuclei/green background

Question 9

Wright-Giemsa stain?

Answer 9

• detection of blood parasites - malaria, rickettsia, Borrelia, Toxoplasma

Question 10

Ziehl-Neelsen stain?

Answer 10

• stain mycobacterium/acid-fast organisms
• basic carbolfuchsin/counterstain methylene blue

Question 11

Kinyoun stain?

Answer 11

• cold acid fast stain (no heating step)
• same as Ziehl-Neelson

Question 12

Auramine-rhodamine?

Answer 12

• same principle as acid-fast stain except fluorescent

Question 13

Modified acid-fast stain?

Answer 13

• has a weaker decolorizer
• for partially acid fast organisms

Question 14

Acridine orange stain

Answer 14

• for detection of bacteria and fungi
• dye intercalates into nucleic acid (native and denatured); at neutral
  pH, bacteria, fungi, and cellular material stain reddish-orange; at acid pH (4.0), bacteria and fungi remain reddish-orange, but
  background material stains greenish-yellow

Question 15

Calcofluor white

Answer 15

• detect fungal elements and Pneumocystis
• bind cellulose/chitin