Unit 4 - Part 8 Fungi Flashcards by sarah smith

What two thing promote fungal growth?

Darkness

2. Moisture

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Are fungi prokaryotes or eukaryotes?

Eukaryotes

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True or False:

Eukaryotic cells have a true nucleus and nuclear envelope, while prokaryotes do not

True

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What are the two forms that fungi can exist in?

Yeast = single celled

2. Mold = multicellular

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Since molds are multicellular, how do to they grow (2)?

Multicellular filaments

OR Hyphae

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Define dimorphic fungi

Considered TRUE pathogens

- can alternate between yeasts and molds (single celled or multicelled)

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What is an example of a Dimorphic fungi

Histoplasma

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What can histoplasma cause?

A systemic disease

- histoplasmosis

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Where does Histoplasma grow?

Grows as a mold in soil

Grows as a yeast in animals and human hosts

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True or False:

Opportunistic fungi have high virulence

False

- they have low virulence

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Define medical mycology

The study of fungi that cause human disease

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What is the classification of fungal disease (mycoses) based on (2)?

Level of tissue involvement

2. Mechanism by which fungi enter the body

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What are two sources of fungi?

Endogenous (from hosts themselves)

2. Exogenous

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What layer of the skin does superficial mycoses infect?

Infect the outermost layer of the skin and hair

- do NOT invade living tissue

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What is an example of a superficial mycoses that infects the hair follicles (folliculitis) on the scalp and eyebrows?

Tinea capitis

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What are the s/s of Tinea Capitis?

Itching, redness, crusted lesions and scaly scalp

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What is another name for cutaneous mycoses?

Dermatophytoses

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What do cutaneous mycoses infect?

Fungi colonize and infect skin, hair and nails

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What is the difference between superficial mycoses and cutaneous mycoses?

Cutaneous have greater invasive properties than those causing superficial mycoses

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What are the s/s of cutaneous mycoses?

Itchy, red round or oval lesions/rash

- may peel off the edges and the center will fade in color

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What is an example of a cutaneous mycoses?

Ringworm

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How do fungi survive in the subcutaneous tissue layers?

By producing proteolytic enzymes and maintaining a facultative microaerophilic environment

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What do proteolytic enzymes break down?

Protein

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What is a characteristic sign of a subcutaneous mycosal infection?

Numerous nodules, abscesses and ulcerative lesions that develop along the lymphatics that drain the primary site of inoculation

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What is the main reservoir of subcutaneous mycoses?

Soil and decaying vegetation

What is the main reservoir of cutaneous mycoses?

Humans, soil and animals

What is the mode of transmission for subcutaneous mycoses?

Indirect transmission | - punctures by splinters and thorns that are contaminated

Define systemic mycoses

Disseminated fungal infections of deep tissues and/or organs

What is the most serious and potentially life-threatening type of mycoses for the elderly and immunocompromised?

Systemic mycoses

What do systemic mycoses often being as?

Respiratory tract infections

What is the main reservoir of systemic mycoses?

Soil | - birds and bat's droppings increase nitrogen levels in soil that promote growth of these fungi

What is the mode of transmission for systemic mycoses?

Airborne

What type of fungal infection does Blastomycosis cause?

Systemic

What are the s/s of blastomycosis?

- flu-like symptoms | varying degree of severity

What systems/parts of the body are affected when a person is infected with Blastomycosis (5)?

- lungs - skin - bones - joints - CNS

Does blastomycosis have a generally long or short incubation period?

Long

What is an example of an opportunistic mycosal infection?

Pneumocystis pneumonia

What are the s/s of pneumocystis pneumonia?

- fever - mild/dry cough - SOB - fatigue - weight loss - chest pain

What is one of the most frequent and severe opportunistic infections seen in the immunocompromised (especially AIDS patients)

Pneumocystis Pneumonia

What was pneumocystis pneumonia originally thought to be, before they discovered it was a fungus?

A protozoa

What is an example of an opportunistic mycosal infection of the mucous membranes of the oral cavity and genital tract?

Candidiasis (Thrush)

What is the mode of transmission for candidiasis (thrush) infections?

Self-infection | - usually when the patient is immunocompromised in some way

What is the treatment for Candidiasis?

Anti-fungal drugs - Nystatin mouthwash - Miconazole cream (vaginal thrush)

What are the risk factors for Candidiasis (thrush)?

- high estrogen levels (before period or around menopause, pregnancy, and oral contraceptive) - low progesterone levels - less competition from mutualistic microbiota (broad-spectrum antibiotics/chemo) - diabetes

Describe the vaginal discharge of candidiasis

"Cottage cheese" | - thick, clumpy, white

Describe the vaginal discharge of bacterial vaginitis

Thin, milky, "fishy" smelling

Describe the vaginal discharge of trichomoniasis

Frothy, gray, (or yellow/green), foul odor

What is an example of an opportunistic mycosal infection of the lungs, meninges, and/or skin?

Cryptococcosis

What is the main reservoir for cryptococcosis?

Environment (trees, decaying wood, soils and bird droppings)

What is the mode of transmission for cryptococcosis?

Airborne/aerosols (inhalation of fungal spores)

What are the s/s of cryptococcosis?

- prolonged cough - SOB - headached - vomiting - fever - weight loss - pneumonia and/or meningitis

Define nosocomial mycoses

Outbreaks of mycoses in health care settings | - airborne and contruction-related

What demographic of patients is extremely susceptible to nosocomial mycoses?

Patient with underlying medical conditions | cancer, leukemia, transplant, COPD

What is the most common nosocomial mycosal infection?

Aspergillus | - aka black mold

Define mycotoxicoses

Fungal diseases caused by ingestion of fungal toxins

What can long-term exposure to mycotoxin lead to?

Damage to the liver, kidneys, lungs, and cancer

Define hypersensitivity to fungi

Allergic reactions to fungi, their spores and metabolites

What is a type 1 hypersensitivity to fungi?

Symptoms similar to hay fever and food allergy

What is a type 3 hypersensitivity to fungi?

Ex: Woodworker's lung | - extrinsic allergic alveolitis due to repeated exposure to Alternaria and Penicillium in wood pulp and dust

What are the risk factors for allergies to fungi?

- genetic predisposition - excess humidity, tightly seal and insulated homes, building leaks, lack of maintenance of humidifies - occupational hazard

True or False: | Fungal spores are less resistant than bacterial spores

True | - remember: bacterial spores are for survival in hostile environments, not for reproduction

True or False: | Fungal spores are "dispersal units" - they can be spread in the environment and to susceptible hosts

True