Download - Systemic mycoses
SYSTEMIC MYCOSES
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large multiple budding yeast
similar to B. dermatitidisParacoccidiodomycosisP a r a c o c c i d i o i d e s
spherule (10-20 u) with endospores
septate mycelium fragment to arthroconidia; colonies are buff or white and moth
CoccidioidomycosisCoccidiodesimmitis
small single budded yeast
septate mycelia microconidia; tuberculate macroconidia colonies are white and buff
HistoplasmosisHistoplasma capsulatum
budding yeast with broad base budseptate mycelium; conidia are
pyriform, globose or double colonies are white or beige, fluffly or glaborous
BlastomycosisBlastomyces dermatitidis
PARASITIC PHASESAPROPHYTIC PHASEDISEASES AND ETIOLOGIC AGENT
SUMMARY OF DEEP MYCOSES
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Monomorphic
No change in form/state in response to stimulus like temperature. Example, yeast at 25° C and 37° C
Examples: Mycelium = Aspergillus species; Yeast = Cryptococcus species
Dimorphic
Change in form in response to stimulus like temperature. Example yeast at 37° C and mycelium at 25° C
Examples: Histoplasma capsulatum; Blastomyces dermatitidis; Paracoccidiodes brasiliensis; Coccidiodes immitis
CHARACTERISTICS TO REMEMBER
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Temperature
Oxidation-reduction potential
Availability of sulfhydril groups
CO2 tension
FACTORS AFFECTING DIMORPHISM
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Dimorphic
Mycelial phase: 25° C
Macroconidia (8-14μm)
Microconidia (2-4μm)
Histoplasma capsulatum
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At 37°C or at body temperature = budding yeast 2-3 x 3-4 μm
Found predominantly in histiocytes
Histoplasma capsulatum
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soil with high nitrogen content, associated with the guano of bats and starlings
rotting guano mixed with soil & feathers of the birds
open environment, soil is nitrogen rich with a rainfall of 35-50 inches and 67-87% relative humidity
caves, the main habitat of bats, which are the reservoir of Histoplasma capsulatum
LIFE CYCLE
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LIFE CYCLE
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CLASSIFICATION OF HISTOPLASMOSIS
TYPE OF INFECTION
SPECIFIC DISORDER COMMENTS
Normal Hosts
• Asymptomatic or mild like flu illness
• Occurs with normal exposure
Normal Hosts• Acute pulmonary
histoplasmosis• Occurs with
heavy exposureNormal Hosts
• Rare complications
• Pericarditis, mediastinal fibrosis
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CLASSIFICATION OF HISTOPLASMOSIS
TYPE OF INFECTION
SPECIFIC DISORDER COMMENTS
Opportunistic Infection
• Disseminated histoplasmosis
• Occurs in individuals who have an immune defectOpportunistic
Infection• Chronic
pulmonary histoplasmosis
• Occurs in individuals who have a structural defect
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CLASSIFICATION OF HISTOPLASMOSIS
TYPE OF INFECTION
SPECIFIC DISORDER COMMENTS
Opportunistic Infection
• Disseminated histoplasmosis
• Occurs in individuals who have an immune defectOpportunistic
Infection• Chronic
pulmonary histoplasmosis
• Occurs in individuals who have a structural defect
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CLINICAL FORMS & SYMPTOMS
TYPE OF INFECTION SPECIFIC DISORDER
Primary acute
• Asymptomatic or flu-like syndrome
Primary acute • Chest pain, shortness of breath and hoarsenessPrimary acute• Radiologically, discrete lung lesion may or may not develop
Chronic cavitary
• Large pulmonary lesions develop
Chronic cavitary • lesions may exist in a relative quiescent stateChronic cavitary• Often mistaken for tuberculosis
Severe disseminated
• Only small percentage progress into this clinical forms
Severe disseminated • Disease of reticuloendothelial system in which organs infection may developSevere disseminated
• In massive dissemination, it could be fatal
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HISTOPLASMOSIS
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Direct Examination: KOH; Wright/Giemsa
Culture: SDA; Smith and Goodman (for contaminated specimen); Yeast Extract = place the CM in a plastic bag
LABORATORY DIAGNOSIS
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Skin test with histoplasmin Ag
CF test
Immunodiffusion test
LABORATORY DIAGNOSIS
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Amphotericin B for disseminated infection
Itraconazole for immunocompromised patients
Cleaning of bat droppings
TREATMENT & PREVENTION
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2 phases: asexual & sexual
Blastomyces dermatitidis (asexual phase)
Ajellomyces dermatitidis (sexual phase)
Dimorphic fungus
Blastomyces dermatitidis
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MYCELIAL FORM
The mycelial phase at 25° C showed typical pyriform microconidia , which are about 2-4 microns in diameter.
YEAST FORM
At 37° C and at body temperature, this organism is a yeast 8-15 microns in diameter.
Buds are produced singly and are attached to parent cell by broad base.
Blastomyces dermatitidis
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LIFE CYCLE
The mode of transmission: inhalation of the spores or the microconidia
Natural habitat: remains an enigma
Favors environment with high nitrogen content, acid pH, abundant moisture, and perhaps enriched with animal excreta
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LIFE CYCLE
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BLASTOMYCOSIS Chicago Disease = Gilchrist’s disease = North American Blastomycosis
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• Indicates systemic disease• May result from direct inoculation from
the soil
Cutaneous
• Extension of pulmonary form• Common sites of involvement are liver
and spleen• Granulomatous lesions are present
Systemic
• Fever, cough and hoarseness• Productive cough, fever and weight loss
after several months• Radiographically resembles tuberculosis
Pulmonary
SYMPTOMSCLINICAL FORMS
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Blastomycin• Has a tendency of high cross reactivity• Little diagnostic value
3. Skin Test
Saborauds, Mycosel or Mycobiotic Agar• Fluffy, whitish brown fungus with pyriform
spores• Culture is not routinely done
2. Culture
20% KOH• specimen is sputum for pulmonary form
and skin for cutaneous form• Biopsy material can also be used• Look for the presence of broad based
buds
1. Direct Microscopic
IMPORTANT FEATURESTESTS
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TREATMENT & PREVENTION
Amphotericin B has been used but with erratic results
2-hydroxystilbamidine
Ketoconazole, less nephrotoxicity
Prevent fomite inhalation in endemic area
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Coccidioides immitis
Amphotericin B has been used but with erratic results
Asexual phase: Coccidiodes immitis
Sexual phase: not known
MYCELIAL STAGE (25°C)
septate hyphae mature in a manner such that alternate cells develop into arthroconidia being separated by vacuolized cells
arthroconidia separate readily and have a “barrel” shape appearance
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Coccidioides immitis
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Coccidioides immitis
YEAST FORM
In tissue and at body temperature:
Develops into spherules (sporangia; 10-60μm) filled with endospores (2-5μm)
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LIFE CYCLE
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COCCIDIOMYCOSIS
Posada’s Disease = San Joaquin Valley Fever = Desert Rheumatism
TREATMENT & PREVENTION
Generally difficult to manage regardless of drug use
Amphotericin B is the drug of choice
Itraconazole and fluconazole have been tried with little success
Prevent spores inhalation
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• 1 in 500 patients progressed into this state
• Fungi spreads into various organs• Prognosis is grave
Disseminated Form
• Precipitin and complement fixation titers appear
• Development of well defined lung cavitation
• Exist for years and could be unnoticed
Benign Form
• Occurs 7-28 days after inhalation of single spore
• Positive skin test• Flu-like fever, malaise and cough• 10% develop erythrema nodosum or
erythrema multiforme
Primary Pulmonary
SYMPTOMSCLINICAL FORMS
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Skin test• conversion back to skin test positive (anergy) is an
indication of grave prognosis
3. Others
Saboraud’s medium with or without antibiotics• room temperature, white fluffy fungus• arthrospores are dangerous to work with• Never try the organism in the petri dish but always
on the bottle or test tube• Examine on the 3rd or 4th day, but must kill
organisms with formalin before attempting to make an LPCB mount
• Can prepare exoantigen
2. Culture
10-20% KOH• sputum, tissue or skin are used as specimen• look for the presence of spherules
1. Direct Microscopic
IMPORTANT FEATURESTESTS
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Paracoccidioimycosis brasiliensis
Dimorphic
Mycelial stage (25°C): no typical sporulation
Yeast stage (37°C): with several budding cells attached to the parent cell, some in a “mariner’s wheel” arrangement
about 2-30μm
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LIFE CYCLE
Transmitted by inhalation of the spores
Restricted to South and Central America
Isolated in acidic soil and its growth requires increased humidity
natural habitat remains to be elucidated
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PARACOCCIDIODOMYCOSIS
South American Blastomycosis = Lutz-Splendore-Almeida’s Disease
A chronic granulomatous disease of skin, mucous membranes, lymph nodes and internal organs
Central and South America more specifically in Brazil
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PARACOCCIDIODOMYCOSIS
Females are as susceptible to infections as males, but the incidence of clinical disease in males is nine times higher
Primary pulmonary disease is often inapparent
Disseminated disease often causes ulcerative lesions of the buccal, nasal and occasionally gastrointestinal mucosa.
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Dr. Supachai Basit
• Paracoccidioidin skin test• Complement fixation test• Immunodiffusion test
3. Others
Saboraud’s • At room temperature it grows a non
spore forming septate fungusBrain Heart Infusion at 35° C• It produces yeast that is seen in tissue
2. Culture
10-20% KOH• 1-2 drops are used• demonstration of multiple budding yeast
1. Direct Microscopic
IMPORTANT FEATURESTESTS
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TREATMENT & PREVENTION
Amphotericin B
Itraconazole
Long term therapy is required
Prevent inhalation of dust in endemic area
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Cryptococcus neoformans
Monomorphic: always in yeast form whether at 25° or at 37° C.
Unique feature: acidic mucopolysaccharide capsule
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LIFE CYCLE
The etiologic agent of cryptococcosis has been recovered in large numbers from the excreta
debris of pigeon roosts, thus it appears to survive well in a dessicated, alkaline, nitrogen-rich and hypertonic environment
There is a close relationship to the habitats of pigeon, but the organism does not infect the bird
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Dr. Supachai Basit
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CRYPTOCOCCOSIS
Busse-Buschke’s Disease, Torulosis, European Blastomycosis
The disease is worldwide in distribution.
This yeast has been repeatedly isolated from sites inhabited by pigeons, particularly their roosts and droppings.
Pigeons are not naturally infected. Wednesday, January 11, 2012
CRYPTOCOCCOSIS
Primary pulmonary cryptococcosis is usually inapparent but may be chronic, subacute or acute.
The clinical entity is most often seen in cryptococcal meningitis.
Osseous and cutaneous disease can be present without apparent neurologic involvement.
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CRYPTOCOCCOSIS: CUTANEOUS FORM
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CRYPTOCOCCOSIS: NEUROLOGIC FORM
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Dr. Supachai Basit
Latex Agglutination TestUrease Test Positive
3. Others
Saboraud’s medium with or without antibiotics
• either at room temperature or at 35° C, the colonies develop after 1-3 weeks incubation as shiny, slimy, light tan yeast colonies
2. Culture
India Ink Stain• Cerebrospinal fluid (CSF) is used as
specimen• The organisms appear as yeast about
8-12 microns in diameter, which are usually surrounded by clear capsules
1. Direct Microscopic
IMPORTANT FEATURESTESTS
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IN CULTURE
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TREATMENT & PREVENTION
Amphotericin B in combination with 5-fluorocytosine have been successful
Fluconazole is as effective too
Clean pigeon droppings
Avoid visiting caves without protective gears
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