INTRODUCTION TO MEDICAL MYCOLOGY
PRACTICAL NO. 1
Practi cal No. 1
(In tr o d u c ti o n to M e d i c a l M y c o l o g y )
Ob j e c t i v e s :
1 - Describe the main characteristics of fungi.
2 - To know how to classify the fungi.
Def i n i t i on of f u n gi
The living world is divided into the five kingdoms of Planta, Animalia, Fungi, Protista and
Monera. It is important to recognize that the fungi are not related to bacteria (Monera).
The main characteristics of fungi are:
1 - Euka ryo t i c: contain cell organelles including nuclei, mitochondria, Golgi
apparatus, endoplasmic reticulum, lysosomes etc. Eukaryotes also exhibit mitosis.
These features separate fungi from bacterial which are prokaryotic cells lacking
the above structures.
2 - Het er ot r oph i c : fungi lack chlorophyll and are therefore not autotrophic
(photosynthetic) like plants and algae; rather they are heterotrophic absorptive
organisms that are either saprophytes (living on dead organic matter) or
parasites (utilizing living tissue).
3 - Like plants, fungi have ri g i d ce l l m e m b ra ne m a d e up o f e rg o st e ro l and
are therefore non-motile, a feature that separates them from animals.
4 - Cel l wal l c on t ai n s c h i t i n : thus, fungi are insensitive to antibiotics.
3rd
Dr. Nessrin AL-abdallat
year Laboratory Medicine, 1434-1435H
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INTRODUCTION TO MEDICAL MYCOLOGY
PRACTICAL NO. 1
Cl a s s i f i c at i on of f u n gi
I. M o r p h o l o g i c a l c l a s s i f i c a ti o n :
1 - Yeas t : unicellular, which is defined morphologically, as a single-celled fungus
that reproduces by simple budding.
2 - Fi l am en t ou s or m ol ds : multicellular, which grow as long branching filaments
called ''hyphae'' and form a mat termed ''mycelium''. Reproduction is by spores
or conidia.
3 - Di m or ph i c : they form different structures at different temperatures. They exist
as molds in the environment at ambient temperature (25oC) and as yeast at
body temperature (37oC).
T y pes of h y p h a e
1 - Tr u e h y ph ae:
a - Se p t a t e d : cells are divided by cross-walls called ''septa'' (Figure 1.1)
e.g. Aspergillus spp.
b - Ase p t a t e d (c o e n o c y ti c ): long, continuous cells that are not divided by
septa (Figure 1.2) e.g. Zygomycete.
2- Ps eu doh yph ae: They are the result of a sort of incomplete budding where the
cells remain attached after division (Figure 1.3) e.g. yeasts.
Fi gu r e 1 . 1 : Septate hyphea
3rd
Fi gu r e 1 . 2 : Aseptate hyphea
Dr. Nessrin AL-abdallat
year Laboratory Medicine, 1434-1435H
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INTRODUCTION TO MEDICAL MYCOLOGY
PRACTICAL NO. 1
Fi gu r e1 . 3 : Pseudohyphae
II. S y s te m a ti c c l a s s i f i c a ti o n :
Based on the type of sporulation; (sexual or asexual).
1 - Se xua l ( p e rfe ct fung i ) : produce "sexual spores":
a - Zyg o sp o re s: spores are produced inside a sporangium e.g. Rhizopus
(Figures 1.4 – 1.6), Mucor (Figures 1.5 – 1.7).
b - Asco sp o re s: spores are produced in a sack called ''ascus'' e.g.
Sacromycete.
c - Bas i di os por es : spores are produced in a sack called ''basidium'' e.g.
Mushroom.
Fi gu r e 1 . 4 : Rhizopus
Fi gu r e1 . 5 : Mucor
Dr. Nessrin AL-abdallat
3rd year Laboratory Medicine, 1434-1435H
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INTRODUCTION TO MEDICAL MYCOLOGY
PRACTICAL NO. 1
Fi gu r e 1 . 6 : Rhizopus
Fi gu r e1 . 7 : Mucor
2 - Ase xua l ( i m p e rfe ct fung i ) : produce asexual spores called "conidia":
a - Th al i c : the conidium is produced from an existing hyphal cell:
i. Art ho sp o re s: hyphae break up into sections to form individual cells
e.g.Coccidiodes immitis (Figure 1.8).
ii. Ch l am y dos por es : one cell develops a thick wall to form a resting spore
e.g. Epidermatophyton floccosum (Figure1.9).
b - Bl as t i c : the conidium is produced by budding:
i. Hol obl as t i c : both the outer and inner wall of conidiogenous cell swell
out to form the conidium e.g. pseudohyphae.
ii. Ent e ro b l a st i c: the outer layer of the hyphal wall being ruptured and an
inner layer extending to become the new spore wall e.g. Aspergillus spp
(Figure 1.10).
Fi gu r e 1 . 8 : Coccidiodes immitis
Fi gu r e 1 . 9 : E. floccosum
Dr. Nessrin AL-abdallat
3rd year Laboratory Medicine, 1434-1435H
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INTRODUCTION TO MEDICAL MYCOLOGY
PRACTICAL NO. 1
Fi gu r e 1 . 1 0 : Aspergillus spp
T y pes of co ni d i a
1 - Mi c r o c o n i d i a : small conidia, one celled conidia e.g. Trichophyton spp
(Figure1.11), Aspergillus spp.
2 - Ma c r o c o n i d i a : large conidai, more than one celled conidia e.g. Microsporum
spp (Figure 1.12), Alternaria spp (Figure 1.13).
Fi gu r e 1 . 1 1 : Trichophyton spp
Fi gu r e 1 . 1 2 : Microsporum spp
Fi gu r e 1 . 1 3 : Alternaria spp
Dr. Nessrin AL-abdallat
3rd year Laboratory Medicine, 1434-1435H
INTRODUCTION TO MEDICAL MYCOLOGY
PRACTICAL NO. 1
III. C l i n i c a l c l a s s i f i c a ti o n :
1 - Sup e rfi ci a l m yco se s: are local infections of outer layer (epidermis) of
keratinizes tissues e.g. skin, hair and nails, e.g. Tinea virsicolor.
2 - Cu t an eou s m y c os es : are local infections of keratinizes tissue, e.g.
Dermatophytes.
3 - Sub cut a ne o us m yco se s: are fungal infections of the dermis, subcutaneous
tissue and bone. They are acquired when the pathogen is inoculated through the
skin by minor cut or splinter wound, e.g. Sporotrichosis.
4 - Syst e m i c m yco se s: are caused by agents of thermally dimorphic fungi. They
are acquired by inhalation, e.g. Coccidioidomycosis.
5 - Op p o r t u n i s t i c my c o s e s : are infections due to fungi with low inherent
virulence. E.g. candidiasis.
Dr. Nessrin AL-abdallat
3rd year Laboratory Medicine, 1434-1435H
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INTRODUCTION TO MEDICAL MYCOLOGY
PRACTICAL NO. 1
Worksheet
Ma t e r i a l s :
1 - Sabouraud dextrose agar (SDA) plate.
2 - Forceps.
3 - Scissors.
4 - Nail cutter.
5 - Alcohol swab.
Exe rci se 1 :
Take your own sample (skin, hair or nail) and culture it on SDA plate.
Method:
1 - Scrapings of scale: take it from the leading edge of the rash after the skin has
been cleaned with alcohol.
2 - Hair: pulled it out from the roots.
3 - Nail clippings.
4 - Put it on the center of SDA plate.
5 - Incubate the SDA plate in 25oC for 5-7 days.
Dr. Nessrin AL-abdallat
3rd year Laboratory Medicine, 1434-1435H
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INTRODUCTION TO MEDICAL MYCOLOGY
PRACTICAL NO. 1
Exe rci se 2 :
Examine the given slides under the light microscope. Draw what you see with labeling.
Mu c o r
Molds
Rh i z opu s
Asp e rg i l l us sp p
Al t e rna ri a sp p
Yeasts
Can di da s pp
Cr y pt oc oc c u s s pp
Dr. Nessrin AL-abdallat
3rd year Laboratory Medicine, 1434-1435H
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