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;
56 Cards in this Set
- Front
- Back
***Cryptococcosis***
|
***Cryptococcosis***
|
|
What is the only encapsulated yeast:
|
Cryptococcus neoformans has a polysaccharide capsule
|
|
Where do people get Cryptococcus neoformans?
|
Pigeon droppings and soil
|
|
Who gets disease from Cryptococcus?
|
Normal and IC hosts
7-8% of AIDS pts |
|
Most common predisposing factor for Cryptococcus in non-AIDs patients:
Other predisposing factors: |
Large doses of adrenal corticosteroids
Sarcoidosis and lymphoma |
|
How do you acquire Cryptococcus infection?
|
Inhalation into lungs (no case clustering)
|
|
Cryptococcus infections in immunocompetent patients are:
Pulmonary infections may be: |
Self-limited
Symp or asymp |
|
What is the major infection of concern with Cryptococcus and how does it occur?
|
Hematogenous spread to CNS occurs even w/ subclinical infections
|
|
Pathogenesis of Cryptococcus
What does the capsule do? How is infection cleared? |
Capsule blocks phagocytosis, interferes w/ complement pathway
Activated T-cells required for clearing of infection (recovery w/ humoral immunity – people get antibodies to it) |
|
How do most people w/ Cryptococcus present?
|
Meningoencephalitis: HA, nausea, gait problems, dementia, irritability, cranial nerve problems and hydrocephalus, mild fever and nuchal rigidity
|
|
What happens to people who go untreated for Cryptococcus?
|
Deepening coma if untreated → death
|
|
What does Cryptococcus look like on chest X-ray?
Other organs affected: |
Well-localized infiltrates
Skin, bone, prostate, other GU sites, hepatitis, pericarditis, endocarditis, endophthalmitis |
|
What occurs w/ disseminated Cryptococcus infections?
|
Raised skin lesions in immunocompromised pts
|
|
Cryptococcus virulence factors (3):
|
1. polysaccharide capsule – India Ink or Capsule stain
2. phenol oxidase enzyme – produces melanin; prevents formation of toxic hydroxy radicals and thus protects fungal cell form oxidative stress and immune defense mechanisms of the host 3. can grow at 37 C (i.e. human body temp) |
|
Lab diagnosis - Cryptococcus on culture:
|
Distinctive brown colonies
|
|
For rapid diagnosis of Cryptococcus:
|
India Ink stain shows large white capsule surrounding the yeast
|
|
What is the best test for picking up Cryptococcus? Uses?
|
Cryptococcal Antigen Latex Agglutination test
Detects antigen in CSF and serum; best for patients w/ cryptococcal meningitis |
|
What histopathological methods are used for Cryptococcus? (3)
|
1. PAS/GMS – stains the cell body but not the capsule
2. Mucicarmine – stains capsular material 3. Methenamine silver (GMS) stain |
|
What is Cryptococcus potential confused for and what test does not allow for this confusion?
|
Coccidiodes immitis; use Mucicarmine stain
|
|
***Histoplasmosis***
|
***Histoplasmosis***
|
|
What type of fungus is H. capsulatum?
Where is the yeast phase found? What does the mold phase have? |
Dimorphic fungus
Yeast phase found in macrophages Mold phase has tuberculate macroconidia |
|
Does H. capsulatum have a capsule?
|
NO!
|
|
Where is H. capsulatum found and in what region of the country?
|
Soil, bird, and bat droppings
Ohio/Mississippi River Valleys (Chicago is on fringe of endemic area) |
|
3 ways that Histoplasmosis may present clinically?
|
1. asymptomatic – antibody present
2. pulmonary – infiltrates and mediastinal lymphadenopathy*; cavitating lesion; fever, night sweats, weight loss (like TB)* 3. disseminated – febrile illness; spread to CNS, skin, adrenals; large liver and spleen |
|
What is the hallmark of H. capsulatum?**
|
Infection of RE by yeasts growing in macrophages**
|
|
Where can Histoplasma yeast spread?
|
Liver, spleen, bone marrow*
|
|
Primary lesion of Histoplasmosis?
|
Granuloma in lung (do sputum sample)
|
|
3 ways to diagnose Histoplasmosis?
|
1. culture of bone marrow, biopsy, BAL – convert mold to yeast (diagnostic); DNA probe of colony
2. skin test – positive test shows past exposure; not used to diagnose acute infection 3. urine antigen test – very sensitive; diagnosis of Histoplasma and Blastomyces |
|
What does Histoplasmosis look like histologically?
|
Intracellular yeast form in multinucleate giant cell
Looks like they have capsules, but they do not |
|
What techniques can be used to diagnose Histoplasmosis?
|
1. Culture media: slow growing colonies; look at both sides of plate (white and brown)
2. Stain: septate hyphae*, right angles; has micro- and macroconidia; macroconidia are tuberculate w/ fingerlike projections (“Mariner’s wheel” on a ship) |
|
***Blastomycosis***
|
***Blastomycosis***
|
|
**Major characteristic of Blastomyces dermatitides?**
|
broad-based budding**
|
|
Where is Blasto found and what is it associated with?
|
central U.S.
in soil and wood |
|
Other name for Blastomycosis?
|
Chicago disease
|
|
What animal other than humans can be infected by Blasto?
|
dogs: they tell you that Blasto is in an area
|
|
Clinical manifestations of Blasto? (4)
|
1. pulmonary
2. skin lesions 3. lytic bone lesions 4. disseminated disease |
|
2 types of pneumonia seen with Blasto infections?
|
1. acute self-limited: resolves in one month
2. chronic pneumo: progressive course, abnormal chest X-ray in 2/3 |
|
What may skin lesions due to Blasto progress to?
|
large ulcers
|
|
What histological stains can be used for Blasto and what is seen?
|
stains: GMS, PAS
large, broad-based budding yeast are observed |
|
Lab diagnosis of Blasto:
|
1. broad-based budding yeast on KOH prep (BBB!)
2. septate hyphae and unbranched short conidiophores ("lollipop shaped") |
|
***Coccidioidomycosis***
(Coccidiodes immitis) aka? |
***Coccidioidomycosis***
"San Joaquin Valley Fever" "Desert Rheumatism" |
|
What does Coccidiodes immitis look like:
in tissue? in culture? |
tissue: spherule filled w/ endospores
culture: mold* w/ barrel-shaped arthroconidia |
|
Is Coccidioides transmitted person-to-person?
|
no!
|
|
Pathogenesis of Coccidioides?
|
inhale arthroconidia --> into alveoli --? monocytes ingest arthroconidia --> they become spherules
|
|
Clinical manifestations of Coccidiomycosis?
|
1. primary infection: fever, cough, chest pain, malaise, hypersensitivity; infiltrates on chest X-ray w/ hilar lymphadenopathy or pleural effusion; mild eosinophilia --> usually resolves spontaneously
2. dissemination to bone, skin, squamous and mucosal tissues, meninges, joints, etc. can follow primary resp infection 3. Erythema nodosum* - rash is an immunologic response to fungus; usually seen in white women |
|
4 methods of lab diagnosis for Coccidiomycosis:
|
1. micro exam: detects spherules*
2. culture: alternating arthroconidia; DNA probe of colony 3. positive skin test (1-4 weeks) 4. antibody serology |
|
Histo exam for Coccidiomycosis shows:
|
spherules containing endospores**
|
|
What do the arthroconidia of Coccidiomycosis look like?
|
thick-walled, barrel-shaped and alternate w/ empty cells
|
|
***Sporotrichosis***
Sporothrix schenckii aka? |
***Sporotrichosis***
aka "Rose Gardener's Disease" |
|
2 forms of Sporothrix and appearance:
|
1. cigar-shaped yeast (37 C)
2. mold w/ daisy like conidiophores (25 C) |
|
Where is S. schenckii found?
What is it assoc with?** |
found in soil
assoc with rose thorns and moss** |
|
Clinical manifestations of Sporothrix? (4)
|
1. papular skin lesions enlarge and ulcerate
2. firm nodules form along lymphatics 3. multiple ulcers 4. disseminates to bones, lungs, eyes, CNS |
|
2 way to get Sporothrix infection:
|
1. inhalation of conidia
2. traumatic inoculation of skin |
|
How do you do a lab diagnosis of Sporotrichosis?
|
culture biopsy: convert mold to yeast phase; no DNA probe
|
|
What does Sporothrix look like on culture?
|
rosette-formation/clusters*
|
|
Shape of Sporothrix is described as:
|
cigar-bodies
|