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Mycology :scientific discipline dealing with fungi
General Characteristics of fungi:
- are Eukaryotic microorganisms.
- Both sexual and asexual spore may be produced.
- Store their food as Store their food as glycogen.
- are heterotrophic organisms.
- Most of fungai aremulticellular, But yeasts are unicellular.
-Cell membrane have ergosterol which is specific target for antifungal agents.
-Cell wall ( Lacks: Peptidoglycan, Techoic acids, Lipopolysaccharide )
(Contains: Peptidomannan , Glycan (target for new antifungal agents)
- Produce filamentous structures.
-Produce spores
-Optimum growth temp is 25-30 C
-Light inhibits fungal growth.
-Can tolerate a wide range of pH (2-9)
-Most fungi are opportunistic.
-Most fungal diseases are not communicable between humans or animals
-Presence of fungus does not mean infections (saprophytic ,common lab
contaminants)
Fungi Groups:
1-MOLD (Filamentous fungi):
Most fungi are composed of filamentous (tubular) structures called hyphae .May be
(septated hyphae OR Aseptated hyphae)
2-Yeasts:are Facultative Anaerobes
-unicelluar
-Reproduce by buddingor fission
Example : Crptococcusneoformans.
3- Yeasts like:
-Unicellular
-Reproduce by budding
-Pseudohyphae are produced
–-Example:Candida
4-Dimorphic Fungi:
-Example:Histoplasmacapsulatum
Source infection of fungi
1-Endogenous
-Normal flora in immunosuppressed patients.
-A cause of hospital acquired infection.
2-Exogenous
Types of Hyphae:
1-Vegetative
2-Aerial
3-Reproductive
Fungal Classification
–Ztygomycetes (sexual reproduction)
-Basidiomycetes (sexual reproduction)
- Ascomycetes (sexual reproduction)
-Deuteromycetes ( NO sexual reproduction)
Mode transmission of fungi:
most fungal diseases are not communicable
1-Respiratory tract : airborne
2-GIT : food & water-born
3- BLOOD
4-Skin contact
Dermaphytosis: (also known as ringworm or tinea) is a superficial fungal infection of
the skin, hair or nails
Zygomycosis : Disease caused by fungi that are classifiable as Zygomycetes
Reproduction of Fungi :
1. Sexual reproduction:Sexual spores
2. Asexual reproduction:Asexual spores
3 Parasexual reproduction :Genetic exchange
Type of SEXUAL Spores :
1. Zygospore
2. Ascospore
3. Basidiospore
4. Oospore
Type of Asexual Spore:
1-Conidiospores (Aspergillusspp ,Penicilliumspp )
2-Blastospores
3-Chlamydospores
4-Sporangiospores
***
-Fungal spores are for reproduction.
-Conidial Fungus: Reproduces by means of asexual spores called conidia
-fungi replicate by mitosis rather than the binary fission employed by bacteria
.
Types of fungal reproduction:
1- budding
2- fission
3- hyphae fragmentation
4- sporulation
Fungi: Steps of Infection
1.Adherence by adhesins .1
2. Invasion
3. Antiphagocytic effect
4. Tissue injury
Fungi : Immunity to infection:
1- Innate (Non-specific) Immunity.
2-Acquired Immunity (Cellular and Humoral )
Mycosis:fungal infection of animals, including humans
Types Humans Mycosis
1) Superficial mycoses
-limited to the outermost layers of the skin and hair.nails e.g. Tineaversicolor
- affect more than 20–25% of the worlds population
-Supported by warm and humid condition.
2) Cutaneous mycoses:
Ringworm fungi & Candidiasis
3) Subcutaneous mycoses
- Caused by saprophytic fungi that live in soil or on vegetation
-Fungal infections beneath the skin
4) Systemic mycoses :fungal infections affecting internal organs: lungs, meninges, Multiorgan disease
5) Opportunistic mycoses
According to source of infection
dermatophytosis:
1-anthropophilic:
generally cause superficial dermatomycosescharacterised by relatively low
inflammatory activity
2-zoophilic:
mycoses of children and adolescents.
They are associated with highly inflammatory skin infections
3-geophilic.
Dermatophytes involve three genera:
; Trichophyton, Microsporum, andEpidermophyton
Dermatomycosis :mycoses of skin.
Pulmonarmycosis :mycoses of lungs.
Cutaneous mycosis are caused by
-Microsporum
-Trichophyton
Opportunistic fungal infection occur in persons:
- Organ transplantation
- Immunosuppressive drugs
- Anticancer drugs
- Broad-spectrum antimicrobials
- HIV-disease
- Drug addicts
Specimens of fungi to lab diagnosis:
Skin scrapings, pieces of nails & hair, sputum, pus etc
Lab diagnosis of fungi:
1-Direct Microscopic Examination:
a-Unstained (KOH) Preparation
b-Stained Preparation:
-Lactophenol cotton blue (LPCB) stain
-Gram-staining (For yeasts : stain gram-positive,)
-India ink preparation
2-Culture:
- Sabourauds Dextrose Agar (SDA)selective medium
-SDA+chloramphenicol (.05%)
Germ tube test most for positive C.albicans
Serological Tests (Abs Detection):
For diagnosis of deep mycoses ..example:
-Precipitation reaction
-Agglutination reaction
-Electrophoretic tests
-Complement fixation
-Indirect fluorescent antibody
Molecular:
-PCR
R.T.PCR
-
Penicillium-EM
A
Mycelium
Hyphae
Fungi
Molds
Yeasts
Dermaphytes
Yeast - Like
Cutaneous mycosis
Superficial mycosis
Systemic mycosis
Aspergillus
Anthropolic
B
Vegetative
Septate / non septate
Glycen
Filamentous fungi
Unicellular
Ringworm
Candida
Candiosis
Nail
Lung
Opptunistic fungal infection
From human to human
T or F
1-Fungi eukaryotic microrganisms ( T )
2-Most human fungal infection are opportunistic infection ( T )
3-Fungi are hetrotrophic organisms ( T )
4-In fungi only sexual spore may be produced ( F )
5- Yeast reproduction : Fission and Budding ( T )
6-fungal spores are for reproduction ( T )
7-Conidial fungus : Reproduces by means of Asexal spores called conidia ( T )
8-Fungi replicate by mitosis ( T )
9-Spore are used extensively to identify Fungi ( T )
10- Fungi contains peptidoglycan ( F )
11-Light inhibits fungal growth ( T )
12-Fungi can tolerate a wid range of PH ( 1-11 ) ( F )
13-Sources of fungal infection : Endo & Exogenous ( T )
14- Subcutaneous or implantation: occure by implantation of spore in wounds ( T )
15-Zoophilic germs: mycoses of females (F )