26 - mycology

mycology

study of fungi

Kingdom Plantae

Under which kingdom were fungi first classified?

they have a unique rigid cell wall different from plants and bacteria, and they are nonphotosynthetic

Why were fungi reclassified from the plant kingdom?

fungal cell wall

polymers of acetyl glucosamine (chitin), forming a thick layer protecting inner organelles from the adverse external environment, made of carbohydrates

cell membrane

contains ergosterol; organized nucleus

Multi-celled hyphae or single-celled yeasts

What are the two forms fungi can take?

Chitin

What is a key structural component that distinguishes fungal cell walls?

Cellulose

What do plants have in their cell walls instead of chitin?

Components of the cell wall, including chitin synthesis

What is a target of many antifungal drugs in the fungal cell wall?

molds, yeast and dimorphic

3 morphological classification of fungi

Hyphae

tubular-like structures that compose a mold colony

Septae

cross walls present in some hyphae (pic on the left); singular: septa

Nonsepate

lacking septae

Hyaline

○ lacking pigment
○ molds do NOT have pigment; they are colorless and transparent

Dematiaceous

containing dark pigment

large round spore in or on hyphae

Chlamydoconidia

Conidia

asexual spores produced by molds with septae

Mycelium

colony; group of hyphae

hypae

help in interexchange of cytosol and organelles between adjacent cells

septate, pauciseptate

hypae may be ? or ?

spores; macroconidia and microconidia

conidia, produced in condidiophere

can be both or either: (2)

chlamydiospore

spores that grown on the hyphae itself (circles)

arthroconidia

bigger segments on the hyphae compared to the septae

yeasts

Unicellular eukaryotic organisms they appear smooth and mucoid on the media; Acquire energy from an organic compound by oxidation.

aerobic conditions

yeasts grow in what conditions

budding

how do Yeasts produce

vacuole

what is one distinctive feature of the yeast, along with the budding

yeast-like fungi

Partly resemble yeast cells, Also develop pseudohyphae resembling hyphal filaments

dimorphic fungi

Exist in both mycelial and yeast forms in varying temperatures

37

dimorphic fungi: at what temp is for yeast like colonies

25

dimorphic fungi: at what temp is for mold like colonies

pathogenic

dimorphic fungi: yeast forms are _

saprophytic

dimorphic fungi: mold forms are _

saprophytic

love to feed on dead plants and animal remains

zgyomycetes

Lower fungi with non-septate hyphae; produce sporangiospores

ascomycetes

Produce septate hyphae and ascopores. (Sexual spores are present inside the sac or ascus)

basidiomycetes

Produce septate hyphae and basidiospores. (Sexual spores are present in the basidium)

deutromycetes or fungi imperfecti

• Produce septate hyphae and cannot be classified into sexual or asexual because their sexual state is unknown.

• Share common features with ascomycetes.

• Most medically important fungi belong to this

  group

sexual or asexual

fungal reproduction

zygospores, ascospores, basidioscores

sexual spores (3)

zygospores

found in between hyphae

basidioscores

Basidium look like goblet cells.

ascospores

found inside the ascus

vegetative spores, aerial spores

asexual spores (2)

vegetative spores

• Formed by budding (yeast cells)

• Formation of septa in hyphal filament (moulds)

• Folding and thickening of hyphal filaments (resulting in thick-walled

  spores)

aerial spores

• Conidiospores

• Microconidia

• Macroconidia

• Sporangiospores

mycoses

They are fungal infections. Term used to describe fungal infections.

inhalation of spores, inoculation of spores, alteration of normal flora, suppressed immune system

4 causes of mycoses to humans

inhalation of spores

causes of mycoses to humans: enter the lungs, get localized, cause respiratory infection

inoculation of spores

causes of mycoses to humans: through cuts, localize in skin.

alteration of normal flora

causes of mycoses to humans: due to overconsumption or heavy dose of antibiotics (alter or kills normal flora that acts as a physical barrier, thus enhancing entry of pathogenic fungi)

suppressed immune system

causes of mycoses to humans: patients undergoing chemotherapy, in steroids due to transplantation, HIV, or diabetics.

superficial, subcutaneous, deep and opportunistic

4 subtypes of mycoses

superficial mycoses

subtype of mycoses: Externally localize on the layers of skin, hair, and nail and grow well on dead layers.

surface and cutaneous

2 types of superficial mycoses

tinea versicolor

Caused by Malassezia globosa

tine versicolor

Is a yeast form of fungi that live on the skin in fewnumbers but multiply during adverse conditions leading to skin infections.

normal flora

what type of flora is tinea versicolor

contact

how is tinea versicolor transmitted

skin scrapings

what is the specimen used in tinea versicolor

KOH (potassium hydroxide) wet mount

tinea versicolor: direct microscopy

this uses: Culture: Saubouraud’s Dextrose Agar, at 32 ̊C - 37 ̊C, 1 week: round and smooth colonies.

Whitfield’s ointment and oral antifungals

2 treatments used for tinea versicolor

tinea nigra

Caused by Hortaea werneckii

tinea nigra

dimorphic fungi that exist in both yeast and hyphae forms, responsible for asymptomatic mycoses, saprophytic in nature and found on dead and decayed materials

cuts and wounds, infections on palms and foot soles

entry of tinea nigra (3)

tinea nigra

It is tolerant to ionic stress, or the ability of tolerance is the ability of an organism to grow at salt concentrations higher than those for growth.this is halo tolerant,

skin scraping of the lesions

lab specimen for tinea nigra

KOH wet mount

direct microscopy for tinea nigra

tinea nigra

what uses this culture:

SDA, at 32 ̊C - 37 ̊C, 3 weeks:

LPCB, lactophenol cotton blue

this uses further testing of isolated colonies in tinea nigra

anti fungal ointments, good hygiene and avoid most places

treatment for tinea versicolor (3)

piedra

This affects the hair

white and black

two types of piedra

hair

lab specimen for piedra

KOH wet mount and hair nodules

direct microscopy for piedra

Sabouraud Dextrose Agar (SDA)

culture for piedra

LPCB

piedra: Further testing of isolated colonies can be done through

 Imidazoles and selenium suphide, Amphotericin B ointments

topical anti fungal ointments for piedra (2)

white piedra

Caused by Trichosporon beigelii

white piedra

• Asexuallyreproductive

• Part of normal flora

• Yeast-like fungi that change to septate hyphal filaments.

• Dimorphic

black piedra

Caused by the fungi, Piedraia hortae.

black piedra Cause disease in living tissues leading to tissue damage.

• Asexual

• Transmitted through contact.

• Mostly asymptomatic

• Hair breakage in extreme cases

subcutaneous mycosis

Cause disease in living tissues leading to tissue damage

mycetoma, chromablastomycosis, rhinosporidosis

three types of subcutaneous mycosis

mycetoma

Persistent subcutaneous granulomatous infection affecting the foot, and as infection progresses, the bones.

A.k.a. Madura foot

mycetoma

Caused by Actinomycetes (Actinomycetoma) or Filamentous fungi (Eumycetoma). — Aerobic, filamentous fungi commonly found in soil.

mycetoma

this disease (?) has the transmission of the ff:

• Inoculation of fungus through cuts or wounds from soil.

• Enter tissue, localize, and replicate inside live cells.

• Spores form clumps inside cells resulting in granules.

❖ Granules vary in color, depending on contributing agents.

pus exudates

what is the specimen used for mycetoma

gram staining, KOH wet mount and culture

direct microscopy for mycetoma (3)

blood agar or nutrient

culture for mycetoma if bacteria is found

sauboraud;s dextrose agar (SDA)

culture for mycetoma if fungi is found

mycetoma

what treatment is this for:

• Surgery and removal of abscess at early stage with proper administration of oral antifungal and antibacterial drug therapy. (to prevent the further spread of the fungi).

  1. Actinomycetoma: Antibacterial drug; Rifampicin, dapsone, and sulphonamides

  2. Eumycetoma: Oral antifungal; Itraconazole and ketoconazole

chromoblastomycosis

• Caused by five different vegetative fungi (pathogens)

  1. Phialophora verrucosa

  2. Fonsecaea compacta

  3. Fonsecaea pedrosoi

  4. Rhinocladiella aquaspersa

  5. Cladophialophora carrionii

chromoblastomycosis

•  Cause persistent infection that slowly progress and form granulomatous lesions.

○ Lead to accumulation of keratinocytes in epidermal layer resulting in sloughing of skin.

• Caused by Actinomycetes (Actinomycetoma) or Filamentous fungi (Eumycetoma).

  ○ Aerobic, filamentous fungi commonly found in soil.

chromoblastomycosis

it is a subcutaneous infection, transmitted through cuts or wounds, primarily in the lag region, it affects the tissues and it drains the lymphatics

pus cells or skin scraping

specimen used for chromoblastomycosis

KOH wet mount, histopathological analysis

methods for lab diagnosis for chromoblastomycosis

SDA, brown or black mold colonies

culture for chromoblastomycosis and the color of the colonies

chromoblastomycosis

this is the treatment for:
Surgery and removal of pustule and proper oral treatment
Heat therapy (early stages)

Antifungal agents: flucytosine, ketoconazole, itraconazole