MYCOVIRO: Introduction to Mycology

Fungi

- Eukaryotic cells

- Lack chlorophyll → does not photosynthesize

- Obligate aerobes or facultative anaerobes

- Heterotrophs

- Require a preformed organic source of carbon → ENERGY

- Principal decomposers

Environment

What is the natural habitat of fungi?

Candida albicans

What fungi is the normal human flora and commonly not found in environment?

Chitin

Fungi are different from other eukaryotes because their cell wall contains?

Chitin

It gives strength and rigidity in the cell wall of fungi?

humid, warm, damp and low saline environment

Fungi usually grow in _____, _____, ______ and _____

environment

Fungi

- human pathogen

- cause spoilage of certain foods

- used in the production of bread, cheese, wine, and beer

Fungi - approx. 4um (Candida)

Bacteria - approx. 1um (Staph.)

Diameter

Fungi -

Bacteria -

Fungi - Eukaryotic

Bacteria - Prokaryotic

Nucleus

Fungi -

Bacteria -

Fungi - mitochondria & endoplasmic reticulum are present

Bacteria - both absent

Cytoplasm

Fungi -

Bacteria -

Fungi - sterols present

Bacteria - sterols absent (except Mycoplasma)

Cell membrane

Fungi -

Bacteria -

Fungi - Chitin

Bacteria - Peptidoglycan

Cell wall content

Fungi -

Bacteria -

Fungi - sexual and asexual spores for reproduction

Bacteria - endospores for survival, not for reproduction

Spores

Fungi -

Bacteria -

Fungi - yes (to some)

Bacteria - no

Thermal dismorphism

Fungi -

Bacteria -

Fungi - require org. carbon, no obligate anaerobes

Bacteria - many do not require org. carbon, many obligate anaerobes

Metabolism

Fungi -

Bacteria -

chitin

carbohydrates and proteins

The cell wall of fungi contains ________ which surrounds the cell membrane. They also contain _________ and _________ and are potent antigens

Ergosterol

Fungi cell membrane are bilayered and contains ____________

Capsule

It is a polysaccharide coating that surrounds the cell wall. It is used as a protection againts phagocytosis

India ink stain

Ink used for capsule of fungi?

Hypha

Morphology:

Basic structural unit?

Mycelium

Morphology:

Aggregates of Hypha?

1. Septate hypha

2. Aseptate hypha

2 forms of Hypha?

Septate hypha

A form of hypha with crosswalk/partitions?

Aseptate hypha

A form of hypha that is continuous?

1. Mold phase

2. Yeast phase

2 phases/types of fungi?

Mold phase

Phase/Types of fungi:

- cottony mycelial mass

- grown on room temp.

- occurs in filaments/hyphae

Yeast phase

solitary cells

Phase/Types of fungi:

- creamy colonies resembling bacterial colonies

- grows at 37 degrees celsius

- consist of ______ cells produce by budding

1. Monomorphic

2. Dimorphic

2 forms of fungi?

Monomorphic

A form of fungi that can only grow in one type, either mold or yeast?

Dimorphic

A form of fungi that is capable of 2 growths, they can exist as mold and yeast?

Sexually or Asexually

Fungi can reproduce ___________ or __________

Asexual reproduction

Reproduction of Fungi:

Fungi imperfecti?

Sexual and asexual reproduction

Reproduction of Fungi:

Perfect fungi?

Asexual reproduction

- through budding/fragmentation/fission

- undergoes MITOSIS

- spores are asexually produced from mycelium

1. Sporangiospores

2. Conidiospores

3. Chlamydospores

4. Arthrospores

5. Blastospores

Types of asexual spores?

Sporangiospores

Asexual spores:

Enclosed in sporangium?

Conidiospores

Asexual spores:

at the end of the hyphae?

Chlamydospores

Asexual spores:

In between hyphae?

Arthrospores

Asexual spores:

Fragmentation of hyphae?

Blastospores

Asexual spores:

budding?

Sexual reproduction

- involves mating/sexual cycle (fusion of 2 hyphae with their nuclei

- Undergoes MEIOSIS

Heterothallic

2 mating systems:

Requires other individual thallus?

Homothallic

2 mating systems:

Have the ability of self-fertile?

Ascospores

Specialized spore-forming structures for reproduction:

They are enclosed in ascus/asci?

Zygospores

Specialized spore-forming structures for reproduction:

Fusion of 2 gametes/haploid nuclei

Oospore

Specialized spore-forming structures for reproduction:

Forms when an oogium (female gamete) is fertilized by an antheridial (male gamete) nucleus?

Basidiospore

Specialized spore-forming structures for reproduction:

Enclosed in a club-shaped Basidium?

1. Inhalation of spores

2. Inoculation by trauma into the skin

3. Direct contact

4. Too much or unnecessary taking antibiotic

What is the mode of infection of fungi?

KOH mount (10%)

Laboratory Diagnosis: Microscopic

It dissolves keratin?

1. India ink

2. Methenamine silver

3. Calcofluor white

Laboratory Diagnosis: Microscopic

What are the stains used?

Periodic Acid Schiff (PAS)

Laboratory Diagnosis: Microscopic

It stains fungi, magenta color?

Lactophenol cotton blue

Laboratory Diagnosis: Microscopic

Blue discoloration of CW?

Saboraud Dextrose Agar

Culture:

Used for General isolation?

Mycosel/Mycobiotic

Culture:

SDA + Cycloheximide and chloramphenicol?

Cornmeal Agar

Culture:

Studying mycelium or pseudomycelium formation, and for the study of Candida species?

Birdseed agar

Culture:

Used for selective isolation and differentiation of Cryptococcus neoformans from other Cryptococcus and other yeast?

Cottonseed agar

Culture:

Use to convert Blastomyces mold to yeast phase?

Germ Tube Test

Biochemical test:

- outgrowth produced by spores of spore

- releasing fungi during germination

- sample is suspended in a serum then examined under microscopy for the presence of germ tube

Mnemonics: STACCH

1. Sporothrix schenckii

2. Trichosporon

3. Aspergillus

4. Cryptococcus neoformans

5. Coccidioides immitis

6. Histoplasma capsulatum

Biochemical test:

What are urease positive fungi?

Hair Perforation Test

Biochemical test:

Use to differentiates Dermatophytes?

Polyenes

Antifungal Therapy:

Binds to Ergosterol; Amphotericin B?

Azoles

Antifungal Therapy:

Inhibits conversion of lanosterol to ergosterol; Miconazole?

Allylamines

Antifungal Therapy:

Inhibits epoxidase; Terbinafine?

Echinocandins

Antifungal Therapy:

Inhibits glucan formation; Caspofungin?

1. Based on Route of Acquisition

2. Based on Virulence

3. Based on Site

Classification of Fungi?

Exogenous Route

Based on Acquisition:

Airborne, Cutaneous (Trauma/Direct Inoculation)

Endogenous Route

Based on Acquisition:

- Colonization by Normal Flora

- Reactivation of Previous Infection

Primary infection

Based on Virulence:

Direct Infection/Establishment of Pathogen?

Opportunistic

Based on Virulence:

Causes Disease in Immunocompromised/Weakened Immune System?

1. Superficial mycoses

2. Cutaneous mycoses

3. Subcutaneous mycoses

4. Deep/Systemic mycoses

Classification Based on Sites?

Superficial mycoses

- Affects the superficial lager of the skin

- Confined to the Striatum corneum

- Does not elicit inflammation

Tinea versicolor

Give the disease under superficial mycoses?

Malassezia furfur

What fungi causes Tinea versicolor?

Cutaneous mycoses

- involve the integument and its appendages, including hair and nails (stratum corneum, or deep layers of the epidermis)

- can elicit inflammation

- Dermatophytosis

- Dermatophytes: Trichophyton, Microsporum, Epidermophyton

Tinea corporis

Disease under Cutaneous mycoses?

Trichophyton

What fungi causes Tinea corporis?

Subcutaneous mycoses

- infects the subcutaneous tissue usually at the point of traumatic inoculation

- inflammatory response develops in the subcutaneous tissue frequently with extension into the epidermis

Sporotrichosis

Disease under Subcutaneous mycoses?

Sporothrix

What fungi causes Sporotrichosis?

Deep/systemic mycoses

involves organ system?

1. Respiratory tract

2. Digestive tract

3. Circulatory system

Routes of deep/systemic mycoses?

Histoplasma capsulatum

Fungi under deep/systemic mycoses?

Thermal dismorphism

What do you call a process that fungi changes faces due to temperature etc. ?

Tinea capitis

Infection of scalp/dandruff?

Cotton blue

A components of Lactophenol that is used as a primary stain?

Lactic acid

A components of Lactophenol that is used as a presevatives?

Phenol

A components of Lactophenol that is used as disinfectant?

Both negative (-)

Trichophyton rubrum

Urease test -

HBT -

Both positive (+)

Trichophyton mentagrophytes

Urease test -

HBT -

1. Oral thrush / Candidiasis

2. Cryptococcosis

3. Tinea inguinuum / hadhad

4. Rose Gardener's disease / Sporotrichosis

5. Tinea / Ringworm

6. Athletes foot / Alipunga / Tinea pedis

7. Vulvo vaginal candidiasis

Give atlease 2 clinical diseases of fungi?