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65 Cards in this Set

  • Front
  • Back
What are the characteristics of the pathogenic dimorphic fungi?
Have different anamorphic forms or phases that are regulated by several biological and physical factors - the most important being temperature.
Is the tissue phase a necessary component for life cycle of the fungus?
Tissue phase is an adaptive response to an altered growth environment and helps make these fungi successful pathogens.
What is the portal of entry for the dimorphic fungi?
Respiratory tract.

Acquired by inhalation of conidia produced by the mould phase.
Is there person to person transmission ?
NO. not directly - tissue phase is NOT transmissable.
Where do primary infections mostly occur?
Respiratory tract.

*Usually are benign or self-limiting.
Progression to serious pulmonary or disseminated disease is dependent on _____.
Immunological response of the host.

*CMI is the primary protective mechanism!
What is special about the location of the pathogenic dimorphic fungi?
Infections caused by these dimorphic fungi are distributed in specific geographic locations = ENDEMIC

(reflects environmental habitat of the mould phase)
What are the 2 etiologic agents of coccidiodomycosis?
C. immitis (San Joaquin Valley, CA)

C. posadasii (TX, AZ, outside US)
Where is coccidiodo endemic?
Southwestern US - up to San Antonio in Texas
What is often the first presenting symptom in coccidiodomycosis?
Allergic manifestations. erythema nodosum due to vigorous immune response.

60% asymptomatic
35% present with flu-like symptoms
Describe the mould phase of Coccidioides spp.
Hyaline, septate hyphae
Matures in 5-10 days

***Hyphae fragment in to barrel-shaped arthroconidia separated by disjunctor cells.
What is the infectious agent of Coccidio?
barrel-shaped arthroconidia are VERY infections

*careful in labs.
Describe the tissue phase of coccidio?
Form multinucleated SPHERULES that undergo repeated internal cleavage to release ENDOSPORES

Spread in tissue as endospore then endospore develops into a spherule
What kind of soil does coccidio inhabit?
Soils found in Lower Sonoran Life Zone
What kinds of environmental perturbations can affect spread of arthroconidia?
Rainfall, windstorms, earthquakes
--> Affect the concentration and spread of arthroconidia in the atmosphere. (usually fairly deep in soil)
What kinds of host more commonly have disseminated disease of coccidioidomycosis?

***CMI important!
Who probably has a genetic predisposition to more serious disease with coccidio infection?
Dark-skinned people
What can cause a DTH response to coccidioidin?
Resolution of disease with give a DTH response

(like lesions, this is due to immune response not lesions filled with fungi!)
What can antibody titers tell in coccidioidomycosis?
Ab response is not protective but can give info about prognosis of disease.

Prolonged and increasing titers of IgG may predict disseminated disease and poor prognosis.
What is used in laboratory diagnosis?
1. Demonstrate organism in tissue = SPHERULES
2. cultivate on solid media = ARTHROconidia
3. Dimorphic conversion
4. DNA probes
5. Serology with IgG and IgM
What kind of serology testing is done on IgG with coccidio?
Complement fixation testing.

Titers should recede = good prognosis
(if don't recede = poor prognosis)
What is therapy for coccidioidomycosis?
Benign pulmonary disease = None

Extrapulmonary = intraconazole, fluconazole, ampB
What is the etiologic agent of histoplasmosis and how is it aquired?
Histoplasma capsulatum

Acquired by inhalation of conidia
What is the severity of histoplasmosis related to?
Related to the severity of dose of conidia.

usually is a self-limiting disease.
A majority/minority of patients will progress to pulmonary or disseminated histoplasmosis.

Seen in immunocompromised and AIDs
Describe the mould phase of histoplasma.
hyaline, septate hyphae

TWO types of conidia: infectious microconidia and tuberculated macroconidia (diagnostic)
Describe the tissue phase of histoplasma?
Oval yeasts usually found in monocytes or macrophages of blood, lungs and RES
Where is histoplasma endemic?
Mississippi River Valley and south-central US (include E. Texas and Htown)
Where does the H. capsulatum organism prosper?
Soils filled with bird and bat guano

*spelunkers beware!
What is the immune response to histoplasmosis?
CMI --> granuloma formation

Also develop DTH response to histoplasmin
How is diagnosis of histoplasma made in the lab?
1. Demonstrate intracellular yeasts in tissue.
2. Cultivate on media and look for tuberculated macroconidia
3. dimorphic conversion
4. DNA probe
5. Serology, Ag testing
What is therapy for histoplasmosis?
Benign = none
Moderate = itraconazole
Extrapulmonary/disseminated = AmpB
What is the etiologic agent of N. American Blastomycosis?
Blastomyces dermatitidis
How is blastomycosis acquired?
Inhalation of microconidia
What is the most common presentation of blastomycosis?
Lesion in lower temperature areas of the body = microabscesses, pustular nodules and crusty verrucous granulomas on hands, face and mucocutaneous.

**Does not typically present as pulmonary disease although acquired by inhalation
What does systemic blastomycosis often involve?
CNS or urogential systems
What happens if blastomycosis is incoulated cutaneously?
Get a rare, mild form of cutaneous disease.
What does extrapulmonary blastomycosis present as?
chronic infection of skin and bones
Describe the mold phase of blastomyces.
Hyaline, septate hyphae in 3-4 weeks

Form oval microconidia
Describe the tissue phase of blastomyces.
Large, thick-walled yeast with a broad-based bud
("figure 8" with broad base at attachment site)
What is the most likely ecological niche for Blastomyces?
Soil and/or decaying organic matter such as wood shavings
Where is blastomycosis endemic?
Mississippi and Ohio River Valleys, mid-easter seaboard; parts of Africa
What is important for immune response in Blastomycosis?
CMI but neutrophil function is also important!

No skin test antigen.
What is used to diagnose blastomycosis in the lab?
1. Demonstrate typical yeast forms in tissue.
2. Cultivate mould phase
3. Dimorphic conversion
4. DNA probe
What is therapy for blastomycosis?
itraconazole, ampB
What is the etiologic agent of paracoccidioidomycosis?
Paracoccidioides brasiliensis

*also called South American blastomycosis
Describe the disease caused by Paracoccidioides.
Chronic granulomatous disease.

Begins as pulmonary infection and disseminates to form ulcerative granulomata of buccal, nasal and occasionally GI mucosa.

Lymph node involvement is common.
What is a rare complication of paracoccidioidomycosis?
Systemic involvement of multiple organ systems is rare.
Describe the mould phase of paracoccidioides.
hyaline, septate hyphae
grow in 2-4 weeks

Oval microconidia
**indistinguishable from Blastomyces dermatidis
Describe the tissue phase of paracoccidioides.
Thin walled yeast with multiple buds arranged in "ship's wheel" formation
- thin points of attachment of buds to mother cell

**Differentiates from Blastomyces
What is the ecology and distribution of paracoccidioides?
Soil of sub-tropical sylcative regions of central and south america
What is the role of immunity in paracoccidioidomycosis?
Like histoplasmosis, skin tests suggest that it can be a benign, self-limiting infection with development of CMI response
What is used for lab diagnosis?
1. Demonstrate multiple-budding yeast in tissue
2. Cultivate mould phase followed by dimorphic conversion to differentiate from blastomyces
What is therapy for paracoccidioidomycosis?
itraconazole, ketoconazole, ampB
What is the etiologic agent of penicilliosis?
Penicilium marneffei
How does penicillinosis differ from the other dimorphic fungi?
It is dimorphic but differs from pathogenic dimorphs because occur in immunosuppressed - esp. HIV-infected individuals.
Where is penicillinosis marnefeii emerging?
In HIV-infected individuals in SE Asia (most cases reported in Thailand and S. China)
How is penicillinosis acquired?
Inhalation of conidia
What other diseases can penicillinosis mimic?
TB, leishmanias, histoplasmosis
What do skin lesions reflect?
Reflect dissemination.

May mimic Molluscum contagiosum-like lesions of face and trunk
How does P. marnefeii differ from other Penicillium spp?
It is the only species known to be dimorphic.
Describe the mould phase of P. marnefeii.
filamentous hyphae with sporulating structures typical of genus.
*colonies may have diffusible red pigment
Describe P. marnefeii in tissue.
Yeast-like organism that divides by fission and shows transverse septation
Intracellular forms of P. marnefeii may mimic yeast phase of ______.
H. capsulatum
What is therapy for penicillinosis marnefeii?
AmpB +/- 5FC followed by itraconazole