Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1357 page)

   Limitations

   The results of fungal cultures may not be available when decisions regarding therapy of acute infection are required. Empiric therapy may be required.

   
Common pitfalls:
Isolation of endogenous
Candida
species or environmental mold contaminants may result in unneeded treatment.

   Other Considerations

   Clinical information, such as travel history, immune status, and animal exposure, should be included on the requisitions for fungal cultures.

   Histopathologic testing and immunologic testing are important methods for diagnosis of invasive fungal infections. Specific molecular diagnostic testing shows promise for sensitive and specific diagnosis with short turnaround time.

   A diagnosis of vaginal and oral candidiasis (thrush) can be made reliably by direct microscopic examination (Gram stain or wet mount) of scrapings of mucosal surfaces without need for fungal culture.

   Detection of antigen or fungal products, such as cryptococcal antigen, histoplasma antigen, β-
D
-glucan, or galactomannan, may be useful for diagnosis.

   The India ink wet mount is less sensitive than cryptococcal antigen testing for meningitis caused by
C
.
neoformans
.

FUNGAL WET MOUNT (KOH, CALCOFLUOR)

   Definition

   A direct examination for fungal elements may provide a rapid detection of fungal infection and is recommended for most types of specimens submitted for fungal culture.

   Use

   This test is used for the direct detection of fungal forms in patient specimens. The specimen is processed to form a liquid suspension of the patient sample.