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Introduction to Clinical Mycology

Part 4



Rapid Methods

Slide 22

March 2012

Now, in terms of what we have available in the clinical laboratory to help make a rapid diagnosis, is the direct microscopic examination of clinical specimens, and that is an old tool, as we talked about. It still is rapid, and it is still very helpful, but it is not 100% sensitive. We have an antigen test for cryptococcal antigen so that we can detect that in body fluids and make a rapid diagnosis in terms of cryptococcal meningitis or disseminated diseases in probably two thirds of the patients. So that is something that is rapid. We still don’t have a lot of real rapid tools yet in mycology. We have nucleic acid probes for identification of dimorphic fungi. We have Real-time PCR identification for things like Histoplasma and Coccidioides that are very useful. And we have nucleic acid sequencing that we can use for identifying organisms, and now we have mass spectroscopy, which is a new tool that is being introduced right now for identifying organisms. And databases are being built for fungi, for dermatophytes, for yeasts, for molds, for trying to identify these and the costs for consumables are minimal and the time for identification is something like 5 minutes. It is a very useful tool. It is going to be out for a lot of promise and that is the way things are probably going to go at least at this time. And then we have PNA-FISH probes. They can be used for detecting fungi in blood cultures and they are very helpful for being able to distinguish one particular type of Candida from another, so that therapy can be started right away. Now mass spectroscopy is being used already in the bacteriology laboratory for identifying bacteria directly from blood cultures. And my guess is what is called MALDI-TOF will be used in the same way for identifying the yeast in fungal blood cultures. And fungi and blood are a very serious event when they get Fungemia, so these PNA-FISH probes and MALDI-TOF are going to play a big role in helping to minimize the death rate due to sepsis due to the some of the yeasts.

Rapid Methods

 


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