Mycology (complete) Flashcards
What are the two distinctive features of fungi
Chitin in the cell walls
Ergosterol in the membranes
What is Dimorphism of fungi
their form changes with temperature
Molds at 26 degrees Celcius
Yeast at 37 degrees celcius
What are mycoses difficult diseases to diagnose and treat
the signs of their diseases are missed or misinterpreted
there are few antifungal agents, and fungi are often resistant to them
Are many mycoses contagious
nope, with the exception of dermatophytes, fungi found on the skin
How are mycoses generally acquired
inhalation, trauma, or ingestion
how does fungal dimorphism play into a fungus’ pathogenicity
in the environment, at lower temperatures, they have mycelia composed of hyphae
in the body, warmer temperatures, they exist as yeasts
Why does it matter that fungi are yeasts when inside the body
because now they are invasive due to the enzymes and proteins they produce to survive in the body
What are the three categories of fungal diseases
- fungal infections
- Toxicoses
- Allergies
What is a fungal infection
the most common fungal disease, caused by a true pathogen, or an opportunistic one, in the body
What is a Toxicoses
When you eat poisonous mushrooms
When do you get fungal allergies
most often results when inhalation of fungal spores occurs
What are the four locations you can get a fungal infection
- superficial - on the skin - no inflammation
- cutaneus - on the skin, hair or nails
- subcutaneos - below skin - traumatic injury
- deep or systemic - in organs or bone (difficult to diagnose and treat)
What are the 4 systemic pathogenic, dimorphic fungi
- Blastomyces
- coccidioides
- Histoplasma
- paracoccidioides
How are the 4 systemic pathogens introduced into the body
inhalation
where do the systemic fungal infections begin, and how do they spread
they begin in the lungs and spread via the blood to the rest of the body
besides blastomyces, coccidioides, histoplasma, and paracoccidioides. how do other fungal infections occur
by opportunistic fungi, that are often commensals, that take advantage of weaknesses in a host’s defense
What makes you most likely to get an opportunistic fungal infection
having a compromised immune system
What is the causative agent of blastomycosis
blastomyces dermatitidis
where is blastomycosis common
south east US and canada
how does one contract blastomycosis
inhalation of dust with the fungal spores being carried into the lungs
what is the most common type of blastomycosis
pulmonary blastomycosis
What are the problems associated with pulmonary blastomycosis
pulmonary lesions that begin asymptomatic
granulomatus reaction with marked fibrosis
can become chronic pneumonia
Where can pulmonary blastomycosis disseminate to
the skin, bone, or in males the prostate
what can blastomycosis cause in AIDS patients
meningitis
how is blastomycosis treated
amphotercin B
What is the common name for coccidioidomycosis
valley fever
where do you find coccidiodomycosis
in the southwestern US, in desert soil, mines, rodent burrows, and archealogical remains
how does a human contract coccidiodomycosis
inhalation of dust that carries the arthrospores (asexual spores) into the lungs
what is the causitive agent of valley fever
coccidioides immitis
what happens to the coccidioides immitis arthrospores once in the lungs
they germinate into spherules that in turn produce more spores that are released into surrounding tissue
Where do most coccidioides infections occur
in the lungs, pulmonary conditions
what happens to healthy individuals who get a coccidioides infection
the infections resolve on their own and require no treatment
What is the preferred drug against coccidioides infections
amphotercin B
what is another name for spelunkers disease
histoplasmosis
what is the causitive agent of spelunkers disease
histoplasma capsulatum
Where can you find histoplasma capsulatum
mostly Eastern US, some in Africa and Asia
what is the most common route of infection of histoplasma capsulatum
inhalation of spores into lungs
what happens once histoplasma capsulatum gets into the lungs
it first attacks alveolar macrophages, then it is dispursed beyond the lungs via blood and lymph
how problematic are most histoplasma capsulatum infections
they are usually asymptomatic and resolve without damage
clinical histoplasmosis can result in one of four diseases what are they
chronic pulmonary histoplasmosis
chronic cutaneous histoplasmosis
systemic histoplasmosis
ocular histoplasmosis
what is the preferred drug against histoplasmosis
Amphotercin B
What disease is the infection pattern of chronic pulmonary histoplasmosis similar to
TB (granulomas and latent reactivation)
What is the causitive agent of paracoccidiodomycosis
paracoccidioides brasiliensis
Where is paracoccidiodomycosis typically found
Mexico and south america
who is most likely to contract paracoccidiodomycosis
farm workers
what other fungal infections are similar to paracoccidiodomycosis
blastomycosis and coccidioidomycosis
What is the drug of choice for paracoccidiodomycosis
amphotercin B or Ketoconazole
What is the most common causitive agent of candidiasis
candida albicans
What is the most common opportunistic fungal infection
candidiasis
are candida part of the natural microbiota, if yes, where
they are common microbiota of the skin and mucus membranes
can candida be transmitted between individuals
yes
how does the dimorphism of candida differ from other fungi
the yeast is the commensal form, the fliamentous forms are more pathogenic
What is the most important fungal pathogen in the oral cavity
candida
What are four clinical manifestations of candida
Thrush
diaper rash
onychomycosis
ocular candidiasis
What is used to treat candidiasis
polyenes (nystatin, amphotercin)
axoles (miconazole, clotrimazole)
DNA analogues (flucytosine)
What is the main causitive agent in cryptococcis
cryptococcus neoformans
where do the spores (that cause disease when inhaled) of cryptococcus neoformans come from
bird droppings
What characteristics of cryptococcus neoformans enhance its pathogenicity
- its ability to resist phagocytosis which is due to a large acidic mucopolysaccharide capsule
- predilection for the CNS
What are the four diseases that can come from cryptococcus infection
- primary pulmonary cryptococcus
- cryptococcal meningitis
- cryptococcoma
- cutaneus cryptococcosis
What are the possible outcomes of primary pulmonary cryptococcus
it can be asymptomatic, mild pneumonia, or develop into chronic pneumonia
what is the most common disease that comes from a cryptococcal infection
cryptococcal meningitis (caused by dissemination of the fungus to the CNS)
What is cryptococcoma?
a rare condition in which solid fungal masses form in cerebral hemispheres or the cerebellum
what is the treatment for cryptococcus infection
synergistic combination of amphotercin B and 5-flurocytosine
What did pneumocystis jirovenci used to be called
P. carnii
pneumocystis jirovenci is a normal member of the human microbiota, when can it become problematic
in AIDS patients, immunosuppressed patients
pneumocystis jirovenci can lead to pneumonia, the presence of the disease is almost diagnostic of _____
AIDS
What is used to treat pneumocystis jirovenci and why
antiprotozoan drugs (septra), because of its similarities to protozoa
What are the most commonly reported fungal diseases
superficial, cutaneous and subcutaneous mycoses
how are superficial, cutaneous and subcutaneous mycoses acquired
person-to person contact or environmental exposure
how serious are superficial, cutaneous and subcutaneous mycoses
they aren’t usually life threatening, but can be chronic or reccuring
do superficial mycoses illicit an immune response
not usually
What is the difference between dermatophytoses and dermatomycoses
dermatophytoses are caused by epidermophyton, microsporum, or trichophyton
dermatomycoses are caused by any other fungi
what are dermatophytoses
fungal infections of the skin or nails caused by dermatophytes
what were dermatophyte infections formerly known as
ringworms
What do dermatophytes use as a nutrient source, and what does that mean for where they reside
they use keratin as a nutrient source, and thus only colonize dead tissue
can dermatophytes damage living tissues
yes by provoking a cell-mediated immune response
what are the three genera of ascomycetes that cause most dermatophytoses
trichophyton
microsporum
epidermophyton fluccosum
What is the treatment for dermatophytoses
topical antifungal agents
What are these common dermatophytoses tinea pedis tinea cruris tinea unguinum tinea corporis tinea capitis
tinea pedis = athletes foot tinea cruris = jock itch tinea unguinum = nails tinea corporis = body tinea capitis = scalp with hair loss
What is immunity to fungi dependent on
activated macrophages
