Method of Staining

Question 1

Most widely used; 1 min. Lactic acid/ glycerol; slides can be made permanent. This method dislodges fungal structures.

Answer 1

Lactophenol Cotton Blue (LPCB)

Question 2

LPCB component that preserve structures.

Answer 2

Lactic Acid/Glycerol

Question 3

Clears specimen using 10-20% KOH; 5 min to 15 min. Add time if more clearing is needed. Add 0.1% thimerosal to preserve specimen. Requires experience because of artifacts.

Answer 3

Potassium Hydroxide (KOH)

Question 4

Stains chitin (cell wall) of fungi. Can be mixed with KOH. Detect fungi rapidly due to bright fluorescence. Requires fluorescence microscope.

Answer 4

Calcofluor White

Question 5

Detects cryptococcus in CSF. Diagnostic of meningitis. Not so sensitive.

Answer 5

India Ink (Nigrosin)

Question 6

Mucopolysaccharide for capsule of Cryptococcus. Detect encapsulated yeast. Blastomyces and Rhinosporidium may also be positive.

Answer 6

Alcian Blue or Mucicarmine

Question 7

Rapid detection of P. jirovecii from lung biopsy/BAL. Quick, easy, rapid results, cost-effective. Trophozoites are not discernable.

Answer 7

Toluidine Blue

Question 8

Examination of bone marrow and blood smear. Detects Histoplasma capsulatum and Cryptococcus spp. Quality of stain should be monitored.

Answer 8

Wright’s Stain

Question 9

Detects fungi; add 5 min time if with counterstain. Hyphae of molds and yeasts can be readily distinguished. Nocardia do not stain well. Time-consuming.

Answer 9

Periodic Acid-Schiff

Question 10

Melanin in fungal cell wall. Differentiates melanin from hemosiderin. If only rare granular staining is present, difficult to interpret.

Answer 10

Masson Fontana

Question 11

Detects fungi in histologic sections. Best stain for fungal elements (black) against pale yellow/green background. Requires specialized staining method.

Answer 11

Methenamine Silver

Question 12

CSF uses:

Answer 12

India ink, cryptococcal antigen

Question 13

Direct examination of tissues

Answer 13

Histology stain, fluorescent antibody (selected organism)

Question 14

Direct examination of skin, hair, nails, and other selected specimens

Answer 14

KOH/KOH with calcofluor white

Question 15

Hyphal elements - width, hyaline vs dematiaceous; septate vs sparsely septate; special supplementary media

Answer 15

Culture - 22 to 25 deg C growth = yeast/mold

Question 16

Culture at 30 deg C

Answer 16

Suspect dimorphic

Question 17

Periodic acid–Schiff color of fungi and background

Answer 17

Magenta against pink/green

Question 18

Gomori methenamine silver color of fungi and background

Answer 18

Black against green

Question 19

Giemsa color of fungi and background

Answer 19

Purple-to-blue yeast with clear halo (capsule), Pink to Purple

Question 20

India ink (negative staining) color of fungi and background

Answer 20

Yeast with clear halo (capsule), Black

Question 21

KOH (clearing agent) color of fungi and background

Answer 21

Refractile, Clear

Question 22

KOH–calcofluor white color of fungi and background

Answer 22

Fluorescent, Dark

Question 23

Masson-Fontana color of fungi and background

Answer 23

Brown, Pink to Purple

Question 24

Two needles to release mycelia from middle-third of colony. Easy but disrupts conidia.

Answer 24

Tease mount method

Question 25

Clear tape, touch only surface, not colony. Retains conidial arrangement but can contaminate culture.

Answer 25

Cellophane Tape Preparation

Question 26

Agar block (1x1 cm) on slide with coverslip, cultured in petri dish with moistened filter paper. Shows natural morphology but is tedious.

Answer 26

Slide culture method