Unit 4 - Part 8 Fungi Flashcards
What two thing promote fungal growth?
- Darkness
2. Moisture
Are fungi prokaryotes or eukaryotes?
Eukaryotes
True or False:
Eukaryotic cells have a true nucleus and nuclear envelope, while prokaryotes do not
True
What are the two forms that fungi can exist in?
- Yeast = single celled
2. Mold = multicellular
Since molds are multicellular, how do to they grow (2)?
Multicellular filaments
OR Hyphae
Define dimorphic fungi
Considered TRUE pathogens
- can alternate between yeasts and molds (single celled or multicelled)
What is an example of a Dimorphic fungi
Histoplasma
What can histoplasma cause?
A systemic disease
- histoplasmosis
Where does Histoplasma grow?
Grows as a mold in soil
Grows as a yeast in animals and human hosts
True or False:
Opportunistic fungi have high virulence
False
- they have low virulence
Define medical mycology
The study of fungi that cause human disease
What is the classification of fungal disease (mycoses) based on (2)?
- Level of tissue involvement
2. Mechanism by which fungi enter the body
What are two sources of fungi?
- Endogenous (from hosts themselves)
2. Exogenous
What layer of the skin does superficial mycoses infect?
Infect the outermost layer of the skin and hair
- do NOT invade living tissue
What is an example of a superficial mycoses that infects the hair follicles (folliculitis) on the scalp and eyebrows?
Tinea capitis
What are the s/s of Tinea Capitis?
Itching, redness, crusted lesions and scaly scalp
What is another name for cutaneous mycoses?
Dermatophytoses
What do cutaneous mycoses infect?
Fungi colonize and infect skin, hair and nails
What is the difference between superficial mycoses and cutaneous mycoses?
Cutaneous have greater invasive properties than those causing superficial mycoses
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
What is an example of a cutaneous mycoses?
Ringworm
How do fungi survive in the subcutaneous tissue layers?
By producing proteolytic enzymes and maintaining a facultative microaerophilic environment
What do proteolytic enzymes break down?
Protein
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
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
