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Introduction to Clinical Mycology

Part 2

Microscopic Examination of Clinical Specimens: Detection of Fungi

Slide 26

January 2012

Terms of being able to detect fungi in clinical specimens, we do have methods for detecting these organisms in clinical samples. The KOH or potassium hydroxide preparation is probably the time honored procedure that has been used for so many years; it still works; it is old but it still works. We add a compound called calcofluor white which is a fluorescent brightener to that and it allows us to be able to use a fluorescent microscope and increase the sensitivity and be able to see morphology better of some of the organisms that are found in clinical specimens. The PAS stain, the Periodic acid-Schiff stain has been used for many years. It is not used so much now in clinical laboratories. It is a tissue stain but it still works. The Gram stain is used for scanning bacteria as you probably know but it also stains fungi and so when you are looking at some of these stains that are not specific for fungi, you need to think Microbiology a little bit because you are apt to find some of these things that don't normally stain the things you are looking for. For example, the Gram stain will stain bacteria well but it also stains fungi. And you need to be conscious of the fact that you can see other things with some of these stains other than what you are just looking for. The Wright's stain is used in Hematology. You can see some of the fungi stain in blood films or on bone marrow cells. You can also see a slide that is in preparation of a spinal fluid to look for cell count.

Microscopic Detection of Fungi


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