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Introduction to FungiIntroduction to Fungi

Glenn S. Bulmer, Ph.D.

Prof. Medical Mycology

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³The best way to win a war ³The best way to win a war 

is to know the enemy´ * is to know the enemy´ * 

This applies to humans as well as

fungus diseases (mycoses).

* Sun Tzu, ³The Art of War´

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What are fungi?What are fungi?

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1). Mushrooms1). Mushrooms

-- over 15,000 species in the worldover 15,000 species in the world

-- several are poisonous to manseveral are poisonous to man

-- the ³mushr oom´ is the ³flower´ of the fungusthe ³mushr oom´ is the ³flower´ of the fungus

-- all mushr ooms repr oduce sexually by meiosis,all mushr ooms repr oduce sexually by meiosis,

the same as manthe same as man

-- the largest part of the mushr oom is the r oot systemthe largest part of the mushr oom is the r oot system

which gr ows in soil, decaying wood. etc.which gr ows in soil, decaying wood. etc.

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2). Hyphae and Spores2). Hyphae and Spores

Both plates air exposed for 5 minutes and

incubated for 1 week 

Sabourauds agar Sabourauds + antibiotics

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Thus, one way we identify fungi is by the

gross appearance of the colony, i.e., the

color, shape, texture, growth habit, etc.

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T

he second method used to identifyfungi is by examining the

microscopic characteristics of the

organism.

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Here are few examples of how fungi

appear microscopically. Note the hyphaeand spores.

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Scopulariopsis, occasional onychomycosis

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 Dreschlera, a dematiaceous fungus

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 N igrospora, a contaminant

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 Rhizopus; zygomycosis, phycomycosis, mucormycosis

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Syncephalastrum, contaminant

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 Aureobasidium, rare pathogen

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 P enicillium, one species is a pathogen

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3). Yeast Cells3). Yeast Cells

These are single cells, usuallyThese are single cells, usually

55--10 micr ons in diameter, which10 micr ons in diameter, which

repr oduce by f orming budsrepr oduce by f orming buds

(blastospores).(blastospores).

The f ollowing are examples of The f ollowing are examples of 

yeasts:yeasts:

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C ryptococcus neoformans, a yeast

surrounded by polysaccharide capsule.

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Saccharomyces, a yeast used to make beer.

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A yeast making buds at the end of long slender tubes.

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An intracellular yeast as seen in histoplasmosis and penicilliosis

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Why are we so concernedWhy are we so concerned

with hyphae and spores?with hyphae and spores?

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This is a picture of many cells in hyphae.

These cells have a thick cell wall with much

chitin. The cell membrane is composed of ergosterol which is similar to cholesterol found

in our cell membrane. These facts are

important in the treatment of patients with

fungus diseases.

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Now what about spores?

Now what about spores?

-These are the small airborne particles by which

fungi reproduce. They are produced by mitosis and

readily disseminate in the air.- R emember the picture of the air -exposed media?

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Sabourauds agar Sabourauds + antibiotics

All of the fungal colonies seen here

came from spores in the air.

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What does this tell you about the ability of fungal

spores to enter the human lung?

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The sketch of the lung shows that

fungal spores must be less than 5-6 microns in

diameter to enter the human lung.

Since many fungal spores are less than

6 microns in diameter the lung is an important

way that fungi enter the body.

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Thus many of the systemic mycoses

are contracted from hyphae and/or spores

which live in the soil and air.

In fact only one serious systemic

mycoses is endogenous in origin

(candidiasis).

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ConclusionConclusionA better understanding of some of the basic

aspects of pathogenic fungi is necessary for us to

 better diagnose and manage patients with systemicmycoses.

Internet searches are an important way to

keep up-to-date on such matters. I recommend the

following search engine:

http://www.pubmed.com

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T

hank You!T

hank You!