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65 Cards in this Set
- Front
- Back
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What are the characteristics of the pathogenic dimorphic fungi?
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Have different anamorphic forms or phases that are regulated by several biological and physical factors - the most important being temperature.
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Is the tissue phase a necessary component for life cycle of the fungus?
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NO.
Tissue phase is an adaptive response to an altered growth environment and helps make these fungi successful pathogens. |
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What is the portal of entry for the dimorphic fungi?
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Respiratory tract.
Acquired by inhalation of conidia produced by the mould phase. |
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Is there person to person transmission ?
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NO. not directly - tissue phase is NOT transmissable.
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Where do primary infections mostly occur?
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Respiratory tract.
*Usually are benign or self-limiting. |
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Progression to serious pulmonary or disseminated disease is dependent on _____.
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Immunological response of the host.
*CMI is the primary protective mechanism! |
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What is special about the location of the pathogenic dimorphic fungi?
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Infections caused by these dimorphic fungi are distributed in specific geographic locations = ENDEMIC
(reflects environmental habitat of the mould phase) |
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What are the 2 etiologic agents of coccidiodomycosis?
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C. immitis (San Joaquin Valley, CA)
C. posadasii (TX, AZ, outside US) |
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Where is coccidiodo endemic?
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Southwestern US - up to San Antonio in Texas
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What is often the first presenting symptom in coccidiodomycosis?
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Allergic manifestations. erythema nodosum due to vigorous immune response.
60% asymptomatic 35% present with flu-like symptoms |
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Describe the mould phase of Coccidioides spp.
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Hyaline, septate hyphae
Matures in 5-10 days ***Hyphae fragment in to barrel-shaped arthroconidia separated by disjunctor cells. |
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What is the infectious agent of Coccidio?
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barrel-shaped arthroconidia are VERY infections
*careful in labs. |
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Describe the tissue phase of coccidio?
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Form multinucleated SPHERULES that undergo repeated internal cleavage to release ENDOSPORES
Spread in tissue as endospore then endospore develops into a spherule |
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What kind of soil does coccidio inhabit?
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Soils found in Lower Sonoran Life Zone
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What kinds of environmental perturbations can affect spread of arthroconidia?
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Rainfall, windstorms, earthquakes
--> Affect the concentration and spread of arthroconidia in the atmosphere. (usually fairly deep in soil) |
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What kinds of host more commonly have disseminated disease of coccidioidomycosis?
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Immunosuppressed.
***CMI important! |
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Who probably has a genetic predisposition to more serious disease with coccidio infection?
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Dark-skinned people
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What can cause a DTH response to coccidioidin?
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Resolution of disease with give a DTH response
(like lesions, this is due to immune response not lesions filled with fungi!) |
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What can antibody titers tell in coccidioidomycosis?
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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. |
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What is used in laboratory diagnosis?
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1. Demonstrate organism in tissue = SPHERULES
2. cultivate on solid media = ARTHROconidia 3. Dimorphic conversion 4. DNA probes 5. Serology with IgG and IgM |
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What kind of serology testing is done on IgG with coccidio?
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Complement fixation testing.
Titers should recede = good prognosis (if don't recede = poor prognosis) |
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What is therapy for coccidioidomycosis?
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Benign pulmonary disease = None
Extrapulmonary = intraconazole, fluconazole, ampB |
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What is the etiologic agent of histoplasmosis and how is it aquired?
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Histoplasma capsulatum
Acquired by inhalation of conidia |
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What is the severity of histoplasmosis related to?
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Related to the severity of dose of conidia.
usually is a self-limiting disease. |
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A majority/minority of patients will progress to pulmonary or disseminated histoplasmosis.
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Minority.
Seen in immunocompromised and AIDs |
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Describe the mould phase of histoplasma.
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hyaline, septate hyphae
TWO types of conidia: infectious microconidia and tuberculated macroconidia (diagnostic) |
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Describe the tissue phase of histoplasma?
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Oval yeasts usually found in monocytes or macrophages of blood, lungs and RES
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Where is histoplasma endemic?
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Mississippi River Valley and south-central US (include E. Texas and Htown)
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Where does the H. capsulatum organism prosper?
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Soils filled with bird and bat guano
*spelunkers beware! |
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What is the immune response to histoplasmosis?
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CMI --> granuloma formation
Also develop DTH response to histoplasmin |
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How is diagnosis of histoplasma made in the lab?
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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 |
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What is therapy for histoplasmosis?
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Benign = none
Moderate = itraconazole Extrapulmonary/disseminated = AmpB |
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What is the etiologic agent of N. American Blastomycosis?
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Blastomyces dermatitidis
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How is blastomycosis acquired?
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Inhalation of microconidia
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What is the most common presentation of blastomycosis?
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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 |
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What does systemic blastomycosis often involve?
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CNS or urogential systems
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What happens if blastomycosis is incoulated cutaneously?
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Get a rare, mild form of cutaneous disease.
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What does extrapulmonary blastomycosis present as?
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chronic infection of skin and bones
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Describe the mold phase of blastomyces.
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Hyaline, septate hyphae in 3-4 weeks
Form oval microconidia |
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Describe the tissue phase of blastomyces.
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Large, thick-walled yeast with a broad-based bud
("figure 8" with broad base at attachment site) |
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What is the most likely ecological niche for Blastomyces?
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Soil and/or decaying organic matter such as wood shavings
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Where is blastomycosis endemic?
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Mississippi and Ohio River Valleys, mid-easter seaboard; parts of Africa
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What is important for immune response in Blastomycosis?
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CMI but neutrophil function is also important!
No skin test antigen. |
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What is used to diagnose blastomycosis in the lab?
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1. Demonstrate typical yeast forms in tissue.
2. Cultivate mould phase 3. Dimorphic conversion 4. DNA probe |
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What is therapy for blastomycosis?
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itraconazole, ampB
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What is the etiologic agent of paracoccidioidomycosis?
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Paracoccidioides brasiliensis
*also called South American blastomycosis |
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Describe the disease caused by Paracoccidioides.
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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. |
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What is a rare complication of paracoccidioidomycosis?
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Systemic involvement of multiple organ systems is rare.
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Describe the mould phase of paracoccidioides.
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hyaline, septate hyphae
grow in 2-4 weeks Oval microconidia **indistinguishable from Blastomyces dermatidis |
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Describe the tissue phase of paracoccidioides.
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Thin walled yeast with multiple buds arranged in "ship's wheel" formation
- thin points of attachment of buds to mother cell **Differentiates from Blastomyces |
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What is the ecology and distribution of paracoccidioides?
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Soil of sub-tropical sylcative regions of central and south america
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What is the role of immunity in paracoccidioidomycosis?
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Like histoplasmosis, skin tests suggest that it can be a benign, self-limiting infection with development of CMI response
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What is used for lab diagnosis?
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1. Demonstrate multiple-budding yeast in tissue
2. Cultivate mould phase followed by dimorphic conversion to differentiate from blastomyces |
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What is therapy for paracoccidioidomycosis?
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itraconazole, ketoconazole, ampB
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What is the etiologic agent of penicilliosis?
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Penicilium marneffei
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How does penicillinosis differ from the other dimorphic fungi?
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It is dimorphic but differs from pathogenic dimorphs because occur in immunosuppressed - esp. HIV-infected individuals.
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Where is penicillinosis marnefeii emerging?
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In HIV-infected individuals in SE Asia (most cases reported in Thailand and S. China)
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How is penicillinosis acquired?
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Inhalation of conidia
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What other diseases can penicillinosis mimic?
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TB, leishmanias, histoplasmosis
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What do skin lesions reflect?
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Reflect dissemination.
May mimic Molluscum contagiosum-like lesions of face and trunk |
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How does P. marnefeii differ from other Penicillium spp?
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It is the only species known to be dimorphic.
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Describe the mould phase of P. marnefeii.
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filamentous hyphae with sporulating structures typical of genus.
*colonies may have diffusible red pigment |
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Describe P. marnefeii in tissue.
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Yeast-like organism that divides by fission and shows transverse septation
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Intracellular forms of P. marnefeii may mimic yeast phase of ______.
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H. capsulatum
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What is therapy for penicillinosis marnefeii?
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AmpB +/- 5FC followed by itraconazole
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