Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
35 Cards in this Set
- Front
- Back
|
What are the 3 morphological types of fungi?
|
1.yeast
2.mold 3.dimorphic |
|
|
Describe the yeast form.
|
*unicellular
*reproduce by budding |
|
|
Describe general features of molds
|
*multicellular
*filamentous w/hyphae *reproduce via spores |
|
|
What are the two forms dimorphic fungi take? What spurs the transition? Name 3 dimorphic fungi.
|
1.mold at ambient temp (~25); has infectious spores
2.yeast at body temp; pathogenic form *histoplasma, blastomyces, coccidioides |
|
|
What are conida?
|
The spores produced by mold fungi.
|
|
|
Describe a structural variation found among hyphae.
|
*aseptate: no cross walls present (is multinucleate)
*septate: has cross walls |
|
|
What is a dematiatious fungus? What's the prognosis with it?
|
*has black and brown pigmented hyphae
*difficult to treat - poor prognosis |
|
|
What fungus might be visulaized with an india ink stain? What feature of this fungus would be particularly evident?
|
Cryptococcus; reveals capsule
|
|
|
What substances are present in the cell wall and in the cytoplasmic membrane of fungi that are not found in bacteria?
|
*wall: chitin
*membrane: sterols |
|
|
Antibacterials are generally not effective against fungi, but there is an exception. What is it?
|
PCP is susceptible to SMZ-TMP.
|
|
|
T/F:
In general, bacteria are larger than yeasts. |
False: yeasts are larger than bacteria.
|
|
|
What is the mechanism of action of amphoteracin B?
|
It binds to ergosterol in the cell membrane - this causes loss of membrane integrity.
|
|
|
Amphoteracin B is a broad spectrum anti-fungal and effective at killing - so why is its use reserved?
|
It is very toxic, especially to the kidneys.
|
|
|
What modifications may make amphoteracin more widely used? What is the drawback to these changes?
|
New liposome technology reduces toxicity, but is extremely expensive.
|
|
|
What is the mode of action of the azoles? What fungi are they effective against?
|
*inhibit ergosterol synthesis
*active against yeasts, Aspergillus, and some dimorphics |
|
|
What is the mode of action of the echinocendins?
|
Block glucan synthesis - glucan is an impt component of the cell wall and is used in the synthesis of chitin.
|
|
|
What form are dermophytes? What is their site of infection?
|
They are molds that produce keratinases and target keratinized tissues (hair, skin, nails)
|
|
|
Name 3 common maladies caused by dermophytes.
|
1.Ring worm
2.Athelete's foot 3.Jock itch |
|
|
T/F:
Dermophytes are generally resolved by an antibody-mediated immune response. |
False: B/c they generally do not invade tissue, dermophytes seldom elicit an immune response of any variety.
|
|
|
What are the 3 genuses of dermophytes that commonly affect humans?
|
1.Trichophytan
2.Microsporin 3.Epidermophytan |
|
|
What form is Sporothrix schenckii? How is it commonly contracted?
|
*dimorphic; cigar-shaped as yeast and thin, septate hyphae with pyriform conidia as mold
*infects SC tissue after trauma with splinters or thorns |
|
|
What happens after sporothrix enters the skin?
|
*forms a papule
*can ascend along lymphatics |
|
|
T/F:
Patients with systemic infection by dimorphic fungus must be kept in negative pressure rooms to prevent spread of infection. |
False: There is no p-p spread with infections of this type. The infection is acquired by inhalation of spores from the environment.
|
|
|
Where is coccidioides considered indigenous? What effect does this environment have on their life cycle?
|
In arid, or semi-arid regions like the american SW and northern Mexico. Dessication leads to formation of infectious spores.
|
|
|
T/F:
The yeast form of coccidioides, the spherule, contains infectious endospores. |
False: contrary to their name, endospores are not true spores and are not infectious.
|
|
|
What environmental factors favor the growth of Histoplasma? Which group of hobbyists are likely to become infected?
|
*bird and bat feces
*spelunkers |
|
|
Which part of the Histoplasma mold form is infectious - microconidia or macroconidia?
|
Microcondida are infectious; the tuberculated macroconidia are not.
|
|
|
Histoplasma is prevalent in what geographical areas?
|
Lower Mississippi River valley, Caribbean basin.
|
|
|
What does the yeast form of histoplasma look like? In what cell can this form be found?
|
*small and lemon-shaped
*seen in macrophages |
|
|
The CXR of a patient with histoplasma can be confused with miliary TB. Why is this?
|
The presence of widespread granulomatous lesions in the lung fields.
|
|
|
Systemic Histoplasma is seen in immunocompromised patients. Specifically, what population and how is the disease manifested?
|
*HIV pts w/CH4+ < 100
*chronic pulmonary presentation |
|
|
How can histoplasma be diagnosed?
|
*bronchoscopy
*blood cultures *bone marrow cultures |
|
|
Name 4 infections that present similar to TB and can be differentiated based on bone marrow culture.
|
*MAC
*histoplasma *blastomyces *brucella |
|
|
What is characteristic of the yeast phase for Blastomyces?
|
Broad-base budding
|
|
|
How can blastomycosis present in its disseminated form?
|
*chronic pulmonary form
*may affect any part of the body: skin lesions, osteomyelitis, and prostate |
