7.2- + HISTOPLASMOSIS+BLASTOMYCOSIS+PARACOCCIDIOIDOMYCOSIS Flashcards
Chronic infection with granulomatous and suppurative lesions, initiated in the lungs
blastomycosis
What organs are commonly affected in disseminated blastomycosis?
Skin and bones
What are the other names for blastomycosis?
North American blastomycosis
Gilchrist’s disease
Chicago disease
What is the etiologic agent of blastomycosis?
Blastomyces dermatitidis
Ajellomyces dermatitidis
Why is blastomycosis more common in males?
Due to occupational and recreational exposure in soil (sometimes riverbanks)
What animal is relatively commonly infected with blastomycosis?
Dogs
Can blastomycosis be transmitted between animals or humans?
No
What is the natural habitat of Blastomyces dermatitidis?
Unknown, but linked to rural riverbanks in small outbreaks
What is the colonial appearance of Blastomyces dermatitidis in the mycelial phase?
On SDA: Initially white, waxy, yeast-like → later cottony with white aerial mycelium, turning tan to brown with age
What is the colonial appearance of Blastomyces dermatitidis in the yeast phase?
On BHI agar with blood: Cream to tan, waxy, heaped or wrinkled; inhibited by chloramphenicol or cycloheximide
What is the growth rate of Blastomyces dermatitidis?
7–28 days
What is the microscopic appearance of Blastomyces dermatitidis in the mycelial phase?
Delicate, septate hyphae with round or pyriform conidia borne singly on conidiophores or directly on hyphae (“lollipop” appearance)
What is the microscopic appearance of Blastomyces dermatitidis in the yeast phase?
Thick-walled, large yeast cells with single broad-based bud and broad isthmus at a constriction
What antigen is used in diagnostic testing for Blastomyces dermatitidis?
Blastomycin (mixture of antigens from culture filtrates)
What is antigen A in Blastomyces dermatitidis?
A specific antigen detected in ID tests for B. dermatitidis
A cell-surface and secreted protein with an immunodominant motif, responsible for generating a protective cell-mediated immune response
BAD-1 in blastomycosis
What is the most common clinical presentation of blastomycosis?
Pulmonary infiltrate with various symptoms; chronic pneumonia may also be present
What histologic reaction is seen in blastomycosis?
Pyogranulomatous reaction with neutrophils and noncaseating granulomas
What is the most common site of skin lesions in disseminated blastomycosis?
Exposed surfaces
What are the characteristics of blastomycosis skin lesions?
Ulcerated verrucous granulomas with an advancing border and central scarring
What other organs can be affected in blastomycosis?
Bone, genitalia, and CNS
Is blastomycosis common in AIDS patients?
No
What specimens are used for blastomycosis diagnosis?
Sputum, pus, exudates, urine, and lesion biopsies
What might wet mounts of blastomycosis specimens show?
Broadly attached buds on thick-walled yeast cells
What culture media is used for blastomycosis?
Sabouraud’s or enriched blood agar at 30°C
How long does it take for blastomycosis colonies to develop?
Usually within 2 weeks
How is Blastomyces dermatitidis confirmed in culture?
Conversion to the yeast form at 37°C on rich medium
Detection of B. dermatitidis antigen A
Specific DNA probe
What serologic test is used for blastomycosis?
Enzyme immunoassay (EIA) for antigen A
What does a high antibody titer to antigen A indicate?
Progressive pulmonary or disseminated infection
What is the treatment for severe blastomycosis?
Amphotericin B
What is an effective treatment for localized blastomycosis?
6-month course of itraconazole
What are the other names for paracoccidioidomycosis?
Lutz-Splendore-Almeida Disease
Paracoccidioidal Granuloma
Lobo Disease
Brazilian Blastomycosis
South American Blastomycosis
In what regions is paracoccidioidomycosis endemic?
Confined to endemic regions of Central and South America, especially Brazil
What is the etiologic agent of paracoccidioidomycosis?
Paracoccidioides brasiliensis
Is paracoccidioidomycosis communicable?
No
In what population is paracoccidioidomycosis most common?
Males in rural areas of Latin America, particularly farmers
What is the natural habitat of Paracoccidioides brasiliensis?
Unknown
What is the appearance of Paracoccidioides brasiliensis in the mycelial phase?
On SDA: White, glabrous, leathery colony → turns tan-brown with age; short aerial mycelium
What is the appearance of Paracoccidioides brasiliensis in the yeast phase?
On blood agar: Cream to tan, moist, wrinkled colony → turns waxy with age
How long does Paracoccidioides brasiliensis take to grow?
Very slow-growing; usually requires 21–28 days
What is the microscopic appearance of Paracoccidioides brasiliensis in the mycelial phase?
Small, septate, branched hyphae with intercalary and terminal chlamydoconidia; few pyriform microconidia
What is the microscopic appearance of Paracoccidioides brasiliensis in the yeast phase?
Large, round to oval, thick-walled yeast cells with multiple buds, attached by narrow constrictions; resembles a “ship’s wheel” (mariner’s wheel/Mickey Mouse cap)
What areas of the body does Paracoccidioides brasiliensis prefer?
Cool areas (e.g., oropharynx, GIT, mouth)
How is paracoccidioidomycosis acquired?
By inhalation of Paracoccidioides brasiliensis, causing initial lung lesions
What happens to pulmonary granulomas in paracoccidioidomycosis?
May become active after dormancy, leading to chronic, progressive pulmonary disease or dissemination
What is the typical age range and gender of patients with paracoccidioidomycosis?
Men, 30–60 years old
What type of infection do younger individuals with paracoccidioidomycosis develop?
Acute or subacute progressive infection with a shorter incubation time
What is the common presentation of chronic paracoccidioidomycosis?
Yeasts spread from the lungs to other organs
What oral symptoms are common in paracoccidioidomycosis?
Painful sores in oral mucosa
What are the characteristics of oral lesions in paracoccidioidomycosis?
Ulcerative lesions with serpiginous (snake-like) active borders and a crusted surface
What histologic findings are seen in paracoccidioidomycosis?
Granulomas with central caseation or microabscesses
Yeasts observed in giant cells or directly in exudate from mucocutaneous lesions
What antigen extract is used for paracoccidioidomycosis testing?
Paracoccidioidin
What antigens can cross-react with paracoccidioidin?
Coccidioidin or histoplasmin
What specimens are used for diagnosing paracoccidioidomycosis?
Sputum, exudates, biopsies, or other lesion materials
What staining techniques are used for direct microscopic examination of paracoccidioidomycosis?
KOH or calcofluor white stain
What culture media is used for Paracoccidioides brasiliensis?
Sabouraud’s or yeast extract agar
What temperature is used to confirm yeast conversion in paracoccidioidomycosis
36°C
What do antibody titers in paracoccidioidomycosis correlate with?
Severity of disease
What is the most effective treatment for paracoccidioidomycosis?
Itraconazole
What other drugs can be used for paracoccidioidomycosis?
Ketoconazole, trimethoprim-sulfamethoxazole
What is the treatment for severe paracoccidioidomycosis?
Amphotericin B
What are the other names for Histoplasmosis?
Spelunker’s disease, Darling’s disease, Reticuloendothelial system cytomycosis
What is the etiologic agent of Histoplasmosis?
Histoplasma capsulatum
What is the teleomorph of Histoplasma capsulatum?
Ajellomyces capsulatum
What is the primary mode of transmission (MOT) of Histoplasmosis?
Inhalation of aerosolized conidia and hyphal fragments
Where does Histoplasma capsulatum grow in the environment?
As a mold in soil and avian habitats, enriched by alkaline nitrogenous substrates in guano
How did Histoplasma capsulatum get its name?
From the appearance of the yeast cells in histopathologic sections
In which regions is Histoplasmosis most commonly seen?
Midwest and Southern USA; endemic in Mississippi and Ohio River Valleys
Where are the endemic areas of Histoplasmosis?
Central and eastern states of the U.S. (Ohio River Valley and Mississippi River Valley)
When does acute Histoplasmosis occur?
When H. capsulatum is disturbed in its natural habitat, such as soil mixed with bird feces (e.g., starling roosts, chicken houses) or bat guano (caves)
Where did the largest urban outbreak of Histoplasmosis occur?
Indianapolis
Is Histoplasmosis communicable from person to person?
No
How can Histoplasma capsulatum be controlled in the environment?
It may be destroyed by spraying formaldehyde on infected soil
A stable variant in Africa that causes African histoplasmosis
Histoplasma capsulatum var. duboisii
How does African histoplasmosis differ from the classical form?
Causes less pulmonary involvement but more skin and bone lesions with abundant giant cells containing yeasts
What is Histoplasma capsulatum var. farciminosum known for?
It causes epizootic lymphangitis in horses
What is the colonial appearance of Histoplasma capsulatum in the mycelial phase?
White to brown or pink mold with a fine, dense, fluffy texture; reverse side may be white, yellow, or tan
What is the colonial appearance of Histoplasma capsulatum in the yeast phase?
Moist, white to cream, heaped colony; may be inhibited by cycloheximide or chloramphenicol
What is the growth rate of Histoplasma capsulatum?
Slow growing; requires 2–4 weeks at 25°C or 30°C
What is the microscopic appearance of Histoplasma capsulatum in the mycelial phase?
Septate hyphae
Round to piriform (pear-shaped) microconidia on soft branches or directly on hyphal stalks
Large, round, thick-walled, knobby tuberculate macroconidia form later
What is the microscopic appearance of Histoplasma capsulatum in the yeast phase?
Small, budding, round to oval yeast cells
Intracellular in mononuclear cells (can be seen with Giemsa or Wright’s stain)
A crude but standardized mycelial broth culture filtrate antigen from histoplasma
Histoplasmin
What does a positive Histoplasmin reaction indicate?
A delayed-type reaction acquired after initial infection
What antibodies can be measured serologically in Histoplasmosis?
Antibodies to both yeast and mycelial antigens
What are the main types of Histoplasmosis
Acute pulmonary histoplasmosis,
chronic pulmonary histoplasmosis,
severe disseminated histoplasmosis
What is the cause of acute pulmonary histoplasmosis?
Inhalation of a heavy inoculum of Histoplasma capsulatum
What are the radiographic findings in acute pulmonary histoplasmosis?
Hilar lymphadenopathy, pulmonary infiltrates, or nodules
In which group is chronic pulmonary histoplasmosis more common
Men, usually due to reactivation and precipitated by underlying pulmonary damage (e.g., emphysema)
Who is at risk for severe disseminated histoplasmosis?
Infants, the elderly, and immunosuppressed individuals
What are the clinical features of disseminated histoplasmosis?
Reticuloendothelial system involvement
Lymphadenopathy
Hepatosplenomegaly
High fever
Anemia
Mucocutaneous ulcers
What does histologic study reveal in Histoplasmosis?
Focal areas of necrosis within granulomas; yeasts may be present in macrophages
What specimens can be used to diagnose Histoplasmosis?
Sputum, urine, lesion scrapings, bone marrow aspirates, buffy coat blood cells, blood films, biopsy specimens
What is the best specimen to detect disseminated histoplasmosis?
Bone marrow cultures
What stains can be used to detect Histoplasma yeast cells?
Gomori methenamine silver, periodic acid-Schiff (PAS), calcofluor white, Giemsa (for bone marrow or blood smears)
What culture media is used to grow Histoplasma capsulatum?
Glucose-cysteine blood agar at 37°C, Sabouraud’s agar, inhibitory mold agar at 25–30°C
What is the minimum incubation period for Histoplasma culture?
4 weeks
How can recovery of Histoplasma be enhanced?
Using lysis centrifugation or fungal broth medium
How is Histoplasma identification confirmed?
In vitro conversion to the yeast form
Detection of species-specific antigen
PCR testing for specific DNA sequences
What serologic test is used to detect antibodies in Histoplasmosis?
Complement fixation (CF) test for histoplasmin or yeast cells
What CF titer indicates progressive disease?
≥ 1:32
What CF antibody indicates active histoplasmosis?
Anti-H antibodies
What CF antibody may arise from past exposure?
Anti-M antibodies
What is the most sensitive test for detecting circulating Histoplasma antigen?
Radioimmunoassay (RIA) or Enzyme immunoassay (EIA)
What happens to the Histoplasmin skin test in progressive disease?
May become negative
What is the treatment for mild to moderate Histoplasmosis?
Itraconazole
What is the treatment for disseminated Histoplasmosis?
Amphotericin B
What maintenance therapy is required for AIDS patients with Histoplasmosis?
Itraconazole
What sequelae may occur after recovery in immunocompetent patients?
Calcification in lungs, liver, spleen
What medium is used to convert Histoplasma to the yeast phase?
Pine’s medium, BHI Blood Agar, Glucose-Cysteine Blood Agar
