fungal

What are the 3 forms of fungi?

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1. Molds, yeasts, mushrooms

What is used for cell wall structure in fungi?

Chitin

### How do fungi acquire energy?

 They absorb it through the environment 

Based on organelle structure, how are fungi classified?

Eukaryotic

Mold

exhibit filamentous growth

Yeast

single celled cells that bud

Yeast-like

produce pseudohyphae

Dimorphic

exist in two different morphological forms

For dimorphic fungi, in what morphological form are they found at 37 C and where would they be found growing?

Yeast in tissue (body temperature) and in vitro (in a lab)

For dimorphic fungi, in what morphological form are they found at 25 C and where would they be found growing?

 At room temperature (22 - 25 C), mold in their natural habitat and in vitro (in a lab)

How would yeast cells be seen on a Gram stain?

Positive

What 2 substances are required for fungi to survive?

Oxygen and Water

What term would be used to describe carbon and energy requirements for fungi?

Chemoheterotrophic

What are parasitic fungi?

Live on living organisms

How do fungi reproduce?

Asexually or sexually by producing spores

In what roles are fungi important in the economy?

Industrial uses- mushrooms/truffles, natural food supply for wild animals, yeast as food supplements (supplies vitamins and cofactors), penicillium, used to alter texture/improve natural favor of natural and processed foods such as the creation of critic acid and food colors, preparation and production of food products such as yogurt

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fermentation- (fruit juices, brewer’s and baker’s yeast, alcohol, fats, proteins

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antibiotics- First observed by Alexander Fleming; noted suppression of bacteria by a contaminating fungus on a culture plate

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plant pathology- Most plant diseases are caused by fungi

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 Medical Importance

What yeast is brewer’s and baker’s yeast?

*Saccharomyces cerevisiae*

Who first recognized that fungi could be used as an antibiotic?

 Alexander Fleming

What was the antibiotic first produced by Fleming?

Penicillin

What fungi is responsible for producing Penicillin?

Staphylococcus

What are most plant diseases caused by?

fungi

In order for fungi to be pathogenic, what 2 requirements must the fungi possess?

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1. must tolerate the temperature of the host site
2. possess an enzymatic system that allows them to parasitize animal tissues

 beneficial effect of fungi in our environment?

decomposers - nutrient and carbon recycling used to trap mosquito larvae in rice paddy fields, helping control malaria

What are 5 harmful effects of fungi in our environment?

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* destruction of food, lumber, paper, and cloth
* animal and human diseases, including allergies
* toxins produced by poisonous mushrooms and within food
* plant diseases
* spoilage of agriculture produce such as vegetables and cereals

What are 3 reasons why there is an increase in the number of fungal infections in humans in recent history?

Increased mobility, immunocompromised/suppressed, and aging population

How are antibody mediated and cellular mediated immunity important in relation to mycoses?

Antibodies are often produced in response to a fungal infection (B-cell humoral) and T-cell immunity is resistant to fungal infections

What is a microscopic and physical description of yeast?

Unicellular, nucleated, rounded and appears as creamy domes with no aerial hyphae on agar plates

In yeast, what term is used to describe “daughter” cells reproduced by budding?

blastoconidia

What is a microscopic and physical description of mold?

multicellular, filamentous with mycelium which may be wooly or fuzzy, identification is often based on the microscopic appearance of the **hyphae** structure

What is the relationship between hyphae and mycelium?

**Mycelium** are long tube-like structures called hyphae which may be vegetative or aerial

How are conidia formed?

After mitosis, through budding from conidigenous or specialized hyphae

How are arthroconidia formed?

asexually produced spores from segmentation of pre-existing fungal hyphae/fragmentation of fertile hyphae

In asexual reproduction of mold, how are molds identified?

formation of structures from asexual reproduction

Explain what happens in sexual reproduction of mold.

Two compatible nuclei join followed by meiosis

Must fungi cause infection in order to survive? 

No, they can survive in the environment without ever causing disease.

Fungal diseases most often relate to what 2 things?

1. health status of the host
2. environmental exposure

What are the 3 barriers to fungal infection?

1. Temperature (cannot grow at 37C)
2. innate immune system
3. acquired immunity

What are examples of innate immune system barriers?

skin, mucosa, hair, surface excretions, endogenous flora, and nonspecific immunity

What are examples of acquired immune system barriers?

antibodies and T-cells

What are examples of disturbances in the epithelial barrier?

Indwelling dialysis, trauma, ulcers, burns, catheters, surgical incision

What are examples of dysfunction in nonspecific immunity?

Chemotherapy, diabetes, radiotherapy

What are examples of dysfunction in T-lymphocyte cell mediated immunity?

HIV/AIDS, Hodgkin’s Lympoma, transplantation with suppressed immune system, chemotherapy and radiotherapy, patients on corticosteroids

What are the 4 groups of clinically significant molds based on sexual reproduction?

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1. Zygomycota
2. Ascomycota
3. Basidiomycota
4. Fungi Imperfecti

Describe zygomycota.

Rapid growing, Known as bread molds, Normally found in soil, opportunistic pathogens. 

What are examples of zygomycota?

 Mucor, Rhizopus, Absidia

Describe ascomycota.

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* saprophytes and parasites of plants
* production of sexual spores - ascospores
* identified by asexual structures

What are examples of ascomycota?

Microsporum canis, trichophyton rubrum, pseudallescheria boydil

Describe basidiomycota

Saprobes and parasites of plants, produce basidiospores in cells during sexual reproduction, only 1 major human pathogen

What is the (one) example of basidiomycota?

Filobasidiella neoformans, sexual form of Cryptococcus neoformans

What are fungi imperfecti?

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* largest number of organisms which are etiological agents of infections

Why would a mold be classified as fungi imperfecti?

organisms placed in this group when no mode of sexual reproduction has been identified

What are examples of fungi imperfecti?

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Aspergillus, cryptococcus, cryptococcus with india ink, rhodotorula, histoplasma.

What are the 6 dimorphic fungi (as listed in the Google slides) causing systemic infections?

Histoplasma capsulatum, blastomyces dermatidis, paracoccidioides brasiliensis, coccidioides immitis, penicillium marneffei, sporothrix schenckii

What are the 4 groupings for classification of fungi?

Geographic grouping, Epidemiologic grouping,  Taxonomy grouping, Topographic grouping

What area(s) of the body are affected by superficial mycoses?

Outermost layers of skin or hair

What are superficial mycoses characteristics?

characterized by discoloration of the skin, depigmentation and scaling of skin

What is unique about superficial mycoses in relation to immune response?

no host cellular / inflammatory response due to organisms being remote from living tissue; essentially no pathology; the disease is recognized purely on cosmetic basis

What part(s) of the body are affected by cutaneous mycoses?

keratinized layer of the skin, hair, or nails

What are signs of dermatomycosis?

 Host response (signs) include itchy, patchy scaling, ring-like patches on skin, or eczema forming eruptions; inflammation may occur.

What is unique about Sporothrix infection?

Sporothrix may present in cutaneous form and disseminate into a systemic infection

What area(s) of the body are affected by subcutaneous mycoses?

deeper layers of skin including connective and muscle tissue

What would be seen in a patient with subcutaneous mycoses?

progressive, non-healing ulcers and presence of draining tracts

How are subcutaneous mycoses tentatively identified?

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presence of a characteristic tissue reaction or granule

What area(s) of the body are affected by systemic mycoses?

affect internal organs or deep tissues of the body; often create symptoms that resemble other diseases

Often, systemic mycoses start as initial infection where in the body?

the initial site is often the lungs where the organism may disseminate via the circulatory system

Symptoms of systemic mycoses include what?

fever and fatigue or chronic cough and chest pain

In what 2 categories can systemic diseases be classified?

a. Those caused by truly pathogenic fungi with the ability to cause disease in the normal human host when the inoculum is of sufficient size

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b. Opportunistic fungi, low virulence organisms, require the patient’s defenses to be lowered before the infection is established

Why are opportunistic infections becoming more common?

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becoming more and more common with a more diverse immunocompromised population

What are the 2 most clinically significant yeasts?

Candida albicans and Cryptococcus neoformans

Saprophytes

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1. any organism that obtains its nourishment from dead organic matter

Aseptate

lacking cross walls

Septate

divided by cross walls

Mycelium

long tube-like structures called hyphae which may be vegetative or aerial

hyaline

colorless, clear

Dematiaceous hyphae

 pigmented, dark in color, usually gray to black

Aerial hyphae (where on agar plate)

growing or existing in the air (top of plate)

Fertile hyphae (where on agar plate)-

bears conidia or spores for reproduction (in the middle??)

Vegetative hyphae (where on agar plate)

absorbs nutrients (bottom of plate)

Dermatomycosis

 disease caused by the organisms is called dermatophytosis

Sporulation

used when there is a fusion of nuclear material / genes combine

Conidia

asexual fungal spores borne externally in various ways from a conidiophore

Macroconidia

multicellular

Microconidia

unicellular

Fungemia

fungal blood infection

Mycetoma

clinical syndrome of localized, tumorous lesions in cutaneous and subcutaneous tissues due to infections, often a foot, with fungi

Mycotoxin

toxins of fungal origins

Germ tube

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1. small projections which arise from cells of certain yeasts; indicates the onset of hyphal formation

Pseudohyphae

a chain of elongated budding cells that have failed to detach (not true hyphae)

Tinea

(Ringworm) - prefix used with the infected area of the body to indicate a cutaneous mycosis

Zoophilic

dermatophytes which are parasitic on lower animals as well as man

Skin

cleaned with 70% alcohol to remove dirt, oil, and surface saprophytes

Nails

cleaned (same as above); usually clipped; need to be finely minced before inoculating media

Hair

obtained from the edge of infected area of the scalp; use a Wood’s Lamp (fluorescence) to help locate infected hair; hair can be obtained by plucking, brushing, or with a sticky tape

Body fluids

normal sterile collection procedures

On the dry envelope, inside the biohazardous packaging, what information should be on the label?

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1. Inside labeling information - patient ID, specimen source, suspected organism
2. Outside labeling information - **WARNING: POTENTIAL PATHOGEN**

In the lab, what is used to examine skin, hair, and nail specimens?

direct examination following KOH preparation

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How are the following specimens processed in the lab?


1. CSF

centrifuged; exam sediment microscopically; inoculate media

How are the following specimens processed in the lab?Blood / bone marrow

generally inoculated directly to BHI  broth and BHI slant.  Extra specimen should be inoculated to other fungal media

How are the following specimens processed in the lab? Tissue

examine for pus, caseous material, or granules; mince aseptically, can use small amount of sterile saline and the supernatant is also inoculated.

For what fungal elements would a wet mount prep be used?

Good for yeast; examination is done in natural environment, so loss of fragile structure is minimal