LAB DIAGNOSIS OF FUNGI (2)

Question 1

Sterile hair fragments (5-10nm) are floated on sterile water.

Hair shafts are removed and microscopically examined in LPCB at weekly intervals up to 1 month.

(-) surface erosion only ( T.rubrum & M. equinum )

(+) forms perpendicular penetration pegs ( T. mentagrophytes & M.canis)

Answer 1

• Hair Perforation Test

Question 2

o 5-day urease test.
o Differentiate T. mentagrophytes from T. rubrum
o Tubes of Christensen urea agar
o (+) urease production; media → peach to bright fuchsia ( T.mentagrophytes)
o (-) T. rubrum

Answer 2

Urease Test

Question 3

o The single most useful nutritional test for dermatophytes.
o Tubes of media with and without thiamine are inoculated with a tiny, medium free portion of colony.
o Miniscule amount of vitamin carried over can cause false (+) growth rxn.

Answer 3

Thiamine Requirement