shows the different fungal infections human can be exposed to. how medical treatment can be carried out to treat use of antofungals. the different parts of the fungus

1. INTRODUCTION TO MYCOLOGY
Dr. Chandrashekhar Unakal
Lecturer In Medical Microbiology
FMS; UWI

2. Introduction / Structure
Mycology is the study of fungi – Yeast and Mold
Yeast are unicellular , nucleated rounded fungi while molds are
multicellular , filamentous fungi
Yeast reproduce by a process called budding while molds produce
spores to reproduce
The name Fungi derived from mykos - meaning mushroom .
The Fungi possess rigid cell walls containing :- Chitin ,
Glucan , Mannans and Cell membranes contains : Ergosterol
All fungi are eukaryotic organisms – nucleus & nuclear membrane ,
endoplasmic reticulum , mitochondria .

3.  Yeasts and Molds have different structural and
reproductive characteristics
Introduction Conti….

4.  Fungi are important as pathogens of Plants , Human and
Animals .
 Over 70% of all Plant diseases are caused by fungi .

5. I. FUNGI (Mycology)
 Many are ecologically important saprophytes ( Consume
dead and decaying matter ) ; Others are parasites .
 Most are multicellular , but yeasts are unicellular .
 Most are aerobes or facultative anaerobes .
 Cell walls are made up of chitin ( Polysaccharide ) .
 Most human fungal infections are nosocomial and / or occur
in immunocompromised individuals ( Opportunistic
infections ) .

6. CHARACTERISTICS OF FUNGI
Morphological Classification Of Medically Important
Fungi
 1. Yeasts
 2. Yeast like fingi
 3. Mold / Filamentous fungi
 4. Dimorphic fungi

7. 1. Yeasts
 Unicellular fungi , non filamentous , typically oval or
spherical cells ( Gram +ve Yeast ) . Reproduce by budding
 E .g : Creptococcus neoformans :- A true yeast fungus ,
capsulated & which is demonstrated by Indian ink staining .
 On culture on SDA – produce smooth , creamy colony .

8. 2 .Yeast like fungi
 Grow partly as yeast & partly as elongated cells resembling hyphae which is
called Pseudohypha . Budding yeasts can form pseudohypha , a short chain of
undetached cells . Reproduce by Budding .
 E g : Candida albicans :- A yeast like fungus with pseudomycellium and Germ
tube test positive .
 Culture on Sabouraud’s dextrose agar ( SDA ) - shows creamy white colony .
Gram stain shows – Gram positive budding yeasts .

9. 3 .Molds / Filamentous Fungi :
 Multicellular , filamentous fungi . Form true mycelia & reproduce by
formation of different types of spore .
 Identified by physical appearance , colony characteristics , and
reproductive spores.E.g : Aspergillus spp , Penicillium spp ,
Dermatophytes ect .
 ◦Thallus : Body of a mold or fleshy fungus . Consists of many hyphae .
 ◦Hyphae ( Sing: Hypha ) : Long filaments of cells joined together .
 ◦Septate hyphae : Cells are divided by cross-walls ( septa ) .
 Aseptate hyphae : Long continuous cells that are not divided by septa .
 Mycelium : Large , visible , filamentous mass made up of many hyphae .

10. Penicillium spp .
 Brush / Broom like arrangement of Conidia .
 Colonies initially Velvety and White but Later become
Powdery & Blue Green .
Lactophenol Cotton Blue stain
Colony on SDA

11. Aspergillus spp.
SDA ( Sabourauds ) /PFA
(Potato Flake Agar) -Green
coloured colonies of
Aspergillus fumigatus
Lactophenol Cotton Blue stain
Conidiophore , Sterigmata ,
Conidia seen

12. 4 . Dimorphic Fungi
 Can exist as both multicellular fungi ( molds ) and yeasts depends on condition of
growth . Mold form produces aerial and vegetative hyphae. Yeast form reproduces by
budding . Primary site of infection – pulmonary
 Dimorphism in pathogenic fungi typically depends on temperature : At 37oC , host
tissue - Yeast form And At 25oC , soil - Mold form . E.g. : Blastomyces dermatitides
, Coccidiodes immitis , Histoplasma capsulatum , Sporothrix schenckii , Penicillium
marneffei , Paracoccidioides brasiliensis .

13. Reproduction and Life cycle of fungi
 Yeast & Yeast like fungi reproduce by budding .
 Filamentous fungi can reproduce asexually by fragmentation of their hyphae .
 Fungal spores are formed from aerial hyphae and are used for both sexual
and asexual reproduction .
 Asexual spores : Formed by the aerial hyphae of one organism . New
organisms are identical to parent .
 Conidiospore : Unicellular or multicellular spore that is not enclosed in a sac .
 Chlamydospore : Thick-walled spore formed within a hyphal segment .
 Sporangiospore : Asexual spore formed within a sac ( sporangium ) .
 Sexual spores : Formed by the fusion of nuclei from two opposite mating
strains of the same species . New organisms are different from both parents .

14. DIVISIONS OF FUNGI – Systematic
Classification – Fungi ( Mycetae ) .
 1. Deuteromycota [ Deuteromycetes ]
( Fungi Imperfecti )
 Not known to produce sexual spores .
 Reproduce asexually .
 Catch - all category for unclassified fungi :
 Candida albicans : Causes yeast infections of vagina in
women . Opportunistic infections of mucous membranes in
AIDS patients .
 Malassezia furfur ( Tinea versicular ) , Sporothrix schenckii
( Rose gardeners ) .

15.  2. Zygomycota [ Zygomycetes ]-
(Conjugation Fungi)
 Also known as bread molds .
 Saprophytic molds with Aseptate hyphae .
 Asexual Reproduction : Occurs via Sporangia .
 Sporangiospore : Asexual spore enclosed within a
sporangium or sac at the end on an aerial hypha
 Sexual Reproduction :Occurs through conjugation &
result in a Zygospore .
 Zygospores : Sexual spores which are enclosed in a
thick , resistant wall. E.g: Rhizopus –Opportunistic
infection in diabetes patients , Mucor .

16.  3. Ascomycota [ Ascomycetes ]- (Sac
Fungi)
 Molds with septate hyphae and some yeasts .
 Asexual Reproduction : Via Conidia - Conidiospores not
enclosed in a sac. Become airborne easily. Form chains (
Broom -like structures ) .
 Sexual Reproduction : Producing Ascospores enclosed in
a sac-like structure ( Ascus ) .
 Include common antibiotic producing fungi and yeasts ,
and several human pathogens .
 ◦Penicillium notatum ( Produces penicillin )
 ◦Aspergillus ( Carcinogenic aflatoxin in peanuts )
 ◦Blastomyces ( Respiratory infections )
 ◦Histoplasma capsulatum ( Respiratory and systemic
infections )

17.  4. Basidiomycota [ Basidomycetes ] - ( Club Fungi )
 Have septate hyphae .
 Include Mushrooms - Amanita , Cryptococcosis – Cryptococcus
neoformans
 Sexual Reproduction :- Produce basidiospores : Spores formed
externally on a club shaped sexual structure or base called basidium.
 Asexual Reproduction :-
 Through budding : e.g. Cryptococcus neoformans - Causes
opportunistic respiratory and CNS infections in AIDS patients .
 ◦ Amanita spp : Mushroom produces lethal toxins to humans .

18. FUNGAL INFECTIONS ( Mycoses )
 Fungal infections or diseases are referred to as Mycosis .
 In general , humans have a high level of innate immunity to fungi and most of the
infections they cause are mild or self limiting . This resistance is due to :
 Fatty acid content of skin ; pH of the skin ; mucosal surfaces ; cilia of respiratory
tract . When fungi do pass the resistance barrier of the human body & establish
infection .
 The Fungal Infections are Classified according to the tissue levels colonised &
Include following types :-
 1. Superficial mycoses
 2. Cutaneous / Dermatophytes Mycoses
 3. Sub-cutaneous Mycoses
 4. Systemic Mycoses
 5. Opportunistic Mycoses

19. 1 . Superficial mycosis
Disease Fungus manifestation
Tinea versicolor Malassezia furfur Decolourisation of skin .
Tinea nigra Exophiala wereneckii Macular patches on skin.( Palm
& Soles ) .
White piedra Tricosporum beigelii Nodules on hair shaft of axilla ,
pubic .
Black piedra Piedraia hortae Black nodules on hair shaft of
scalp , beard .
Tinea versicolor-Pitriasis versicolor
Tinea nigra
White piedra
Black piedra

20.  caused by Malassezia
furfur
Hypopigmentation
Dark-colored macule due to accumulation
of a melanin like substance in the
fungus.Caused by Exophiala wereneckii
Characterised by soft , white or light
brown nodules , on axillary / pubic
hair.Caused by Tricosporum beigelii
Black hard nodules on hair shafts of
scalp & beard .Caused by Piedraia
hortae .
Tinea versicolor Tinea nigra White piedra Black piedra

21. 2 . Cutaneous mycoses:
 Fungal infections of the skin , hair , and nails ( Dermatophytes , dermatophytoses )
 Infection is transmitted by direct contact or contact with infected hair ( hair salon ) or cells ( nail
files ) . Examples : - Ringworm ( Tinea capitis and T. corporis ) ; Athlete’s foot ( Tinea pedis ) ;
Jock itch ( Tinea cruris )
Ringworm skin infection:
Tinea corporis
Candida albicans
infection of the nails.
Severe nail infection with
Trichophyton rubrum

22. Dermatophytes – Macroconidia :
Trichophyton rubrum Microsporum gypseum Epidermophyton floccosum
Pencil shaped - Septate
Up to 10 , Thin walled .
Spindle shaped -
Thick walled - 4-6 septa .
Club shaped in clusters -
Smooth walled - 3-4 septa .

23. Ring worm
Tinea capitis Tinea corporis
Tinea pedis
Tinea manuum&T.
pedis&T.unguium

24. 3 . Subcutaneous mycoses
 Fungal infections beneath the skin , involving the dermis ,
subcutaneous tissues , muscle and fascia , also the bones .
 Caused by saprophytic fungi that live in soil or on vegetation .
 Infection occurs by implantation of spores or mycelial
fragments into a skin wound .
 Can spread to lymph vessels . They include Sporotrichosis
( Sporothrix schenckii ) ; Chromoblastomycosis ( Fonsecea
pedrosoi , Fonsecaea compactum ) ; Mycetoma ( Madurella
grisea , Madurella mycetomatis ) .

25. Sporothrix schenckii
 Sporotrichosis ( Rose-
Gardener’s Disease ).. Portal of
entry – Skin .
 Lymphocutaneous variety
occurs when contaminated
plant matter penetrates the skin
& the pathogen forms a nodule,
then spreads to nearby lymph
nodes .
Primary sore and series of secondary
nodules along lymphatic chain in the arm
Lymphocutaneous Sprotrichosis

26. 4 . Systematic Mycoses
Fungal infections deep within the body . Can affect a number of tissues & organs
- causing pulmonary & systematic infection from airborne conidia .
a) Blastomycoses : ( Blastomyces dermatitidis ) - Acute & chronic
infection of lungs common in USA & Canada .
b) Histoplasmoses : ( Histoplasma capsulatum ) :- Associated with
droppings of bats & birds . Human infection by inhalation of spores -
Initial infection in Lungs . Later spreads through blood to most
Organs . Common in USA .
c) Coccidioidomycoses : ( Coccidioides immitis ) - Causes pulmonary
infection ( Resembles Tuberculosis ) common in USA and Mexico .
d) Cryptococcosis : ( Capsulated yeast - Cryptococcus neoformans )
–Found in droppings of birds , infection frequently seen in patents
with AIDS with meningitis & lung infections .

27. Opportunistic Mycoses
Infection under special condition such as Immuno- compromised
patient , associated with HIV , wide use of antibiotics , steroids .
a) Candidiasis : ( Candida albicans )- Yeast like , causes oral thrush ,
cutaneous candidiasis , meningitis , septicemia & nail infection .
b) Aspergillosis : ( Aspergillus sp. ) – Filamentous fungi , causes
pneumonia , aspergilloma, otitis , keratitis & aspergillous asthma.
c) Mucormycoses / zygomycosis : ( Mucor , Absidia , Rhizopus ) –
Cotton like growth on roof of mouth , paranasal sinuses .
d) Pneumocystitis: ( Pnumocystic carinii )- Causes pneumonia with
high mortality in AIDS , malignancies & autoimmune disease .

28.  TOXICOSIS : 2 types of fungul toxicosis
 A – Mycotoxicosis : Result from consumption of feeds or food
products contaminated with toxin - producing fungi e .g : Afla- toxin
by Aspergillus flavus ( grow in ground nuts & cereals ) ; Mycotoxin by
Fusarium spp ; Fumigatin toxin by Aspergillus fumigatus .
 B – Mycetismus : Results from ingestion of fungi containing
preformed toxin e. g : Mushroom poisoning .

29. Laboratory Diagnosis of fungi
 Specimens for fungi identification in the microbiology laboratory
could include :
 Hair ; Nail ; Skin scrappings
 Tissue biopsy
 Cerebrospinal fluid ( CSF )
 Sputum , Broncho-alveolar larvage ( BAL )
 Blood or Any other body fluid : – Urine , Pleural fluid ,
Peritoneal fluid

30. Lab Diagnosis-Microscopy & Staining
 Microscopy – Staining types
 Wet preparations , treat with 10% KOH , with 5% glycerin
or Calcoflour staining .
 Lactophenol cotton blue staining
 Haematoxylin & Eosine stain
 India Ink stain
 Woods lamp :– Fluorescence of fungi under UV light for
Microsporum spp .

31. Fungal Culture
Culture –Growth slow . ( Tube & Slide culture ) .
 Sabourauds’s Dextrose agar ( SDA ) – favours fungal growth because of
low pH , Potato dextrose or rice flake or cornmeal agar at 25 or 37oC
 Mycosel agar – selective for pathogenic fungi because of chloramphenicol
and cycloheximide in medium
 Growth On the agar – Visualize morphology of colony , Spores , Cells ,
Hypha ( aseptate , septate ) .
 Spores – conidiospores , sporangiospore , arthrospore , chlamydospore
 Yeast morphology – size , pseudohyphae , capsule ( India Ink Stain )

32.  Biochemical tests
 Germ tube formation
 Pseudohyphae formation
 Urease ; Fermentation and Assimilation studies
 Immunoassay
 Latex agglutination test , Enzyme assay ( ELISA ) .
 Molecular tests
 Polymerase Chain Reaction ( PCR ) .

33. Treatment of Fungal Infections
 Macrolides e.g.Amphotericin B , Nystatin : Bind to Ergosterol
 Azoles-e.g. Ketoconazole , Econazole , Fluconazole , Miconazole
Ketoconazole : Termination of cell membrane synthesis .
 Allylamines –e.g. Terbinafine : Inhibits Ergosterol synthesis .
 Pyrimidine analogs – Flucytosine :Inhibits DNA & RNA synthesis
 Grisans –Griseofulvin :Inhibits Fungal Mitosis.Rx -Dermatophytosis
 Caspofungin : Inhibits fungal cell wall synthesis .

34. Thank You.

35. vesicle
phialides
The following picture shows culture on SDA and Lactophenol cotton blue stain of
fungus. A fungi characterized by a vesicle – swollen tip to the conidiophore stalk upon
which phialides are mounted .
Which of the following is a disease caused by the fungi shown above in immuno-
compromised individuals ?
A. Onychomycosis
B. Otomycosis
C. Aspergillosis
D. Penicilliosis
Growth on SDA
Q1.
Sample spotter Question MDSC 1002