Systemic Mycoses

Question 1

Blastomycosis

Answer 1

Blastomyces dermatitidis
Dead/decaying material
Recreational/occupational exposure
Southeastern and central states: overlaps with Histoplasmosis, more towards the Carolinas and His on the Miss

Question 2

Blastomycosis pathogenesis

Answer 2

Inhalation of infectious particles

Inhalation of conida: asymptomatic, pulmonary disease, or extrapulmonary disseminated disease

Question 3

Blastomycosis clinical findings

Answer 3

50% asymptomatic
Pulmonary infection:
mild flu-like
severe resembles bacterial lobar PNA with high fever lobar infiltrates and cough
fulminant adult resp disease has high fever diffuse infiltrates and resp failure
subacute or chronic resembles TB or lung cancer, pulmonary mass lesions or fibronodular infiltrates
Chronic cutaneous:
Result of hematogenous dissemination, absence of pulmonary lesions, lesions are papules pustular indolent ulcerative-modular or verrucous, differential is squamous cell carcinoma
Extrapulmonary disseminated disease:
Skin and bone, prostate liver spleen kidney and CNS

Question 4

Blastomycosis diagnosis

Answer 4

Direct microscopy: sputum bronchoalveolar lavage or lung biopsy, presence of BRIAD BASED BUDDING YEAST
Culture: mycelia form not diagnostic, must convert to yeast
Immunidetection: exoantigen A
In situ hybridization

Question 5

Blastomycosis treatment

Answer 5

Antifungal: Amphotericin B

Corrective surgery

Question 6

Coccidioidomycosis

Answer 6

C. Immitis in California
C. Posadasii outside California
SW USA, northern Mexico, Central and South America

Question 7

Coccidioidomycosis pathogenesis

Answer 7

Most virulent of all mycotic pathogens
Inhalation of infectious particles, arthroconidia
Conversion to spherules in the lung -> spherules produce endospores -> progressive cleavage -> endospores released and form new spherules

Question 8

Coccidioidomycosis clinical presentation

Answer 8

Primary disease:
Asymptomatic in most
Flu-like illness
Hypersensitivity: immune complex formation
Secondary coccidioidomycosis:
Nodules, cavitary disease or progressive pulmonary disease
Disseminated disease:
Chronic/fulminant
Infection of lungs, meninges, bones and skin

Question 9

Coccidioidomycosis diagnosis

Answer 9

Direct microscopic histopatholigic examination: 
sputum, exudate, or tissue
Endosporulating spherule
Culture:
Due to highly infectious nature, culture is potential source of infection
Serology:
Agglutination and precipitin test
Complement fixation

Question 10

Coccidioidomycosis treatment

Answer 10

Primary: supportive care

Secondary or disseminated: Amphotericin B, Itraconazole, Fluconazole (particularly for meningitis)

Question 11

Histoplasmosis

Answer 11

Histoplasma capsulatum
Variant capsulatum: pulmonary and disseminated disease, eastern US and Latin America
Variant duboisii: skin and bone lesions, tropical areas of Africa
Both are thermal dimorphs
Found in soil, bat and avian habitats (soil with high nitrogen content)
Most endemic in Ohio, Mississippi, and Kentucky

Question 12

Histoplasmosis pathogenesis

Answer 12

Inhalation of microconida that was aerosolized by disturbance of soil
Phagocytosis by alveolar macrophages and neutrophils
Microconida convert budding yeast cells intracellular lay
Suppression of cell mediated immunity
Infection stays localized or disseminates

Question 13

Variant capsulatum clinical findings

Answer 13

Pulmonary infection:
Most asymptomatic (low exposure)
Self limiting flu-like illness (high exposure)
Lymphadenopathy and pulmonary infiltrate
Progressive pulmonary histoplasmosis:
Chronic pulmonary symptoms
Apical cavities and fibrosis
Progressive destruction secondary to immune response
Disseminated:
Chronic has weight loss and fatigue, oral ulcers and hepatosplenomegaly
Subacute has fever weight loss and malaise, oropharyngeal ulcers and hepatosplenomegaly, bone marrow involvement may lead to anemia leukopenia and thrombocytopenia, fatal if left untreated
Acute: fulminant process in immunicompromised pts, septic shock like presentation

Question 14

Variant duboisii African histoplasmosis differentiation

Answer 14

Larger thick walled yeast cells
Pronounced giant cell formation in infected tissue
Diminished pulmonary involvement
Greater frequency of skin and bone lesions

Question 15

Histoplasmosis diagnosis

Answer 15

Direct microscopic and histopathologic examination: sputum tissue bone marrow CSF blood, normally intracellular and clustered together
Culture:
Mold hyphae microconida and macroconidia
Conversion to yeast at 37C on enriched medium
Serology: Ag and Ab detection

Question 16

Histoplasmosis treatment

Answer 16

Most individuals recover without treatment

Chronic and disseminated require anti-fungal therapy
Amphotericin B, Itraconazole
Possible resection of pulmonary lesions

Question 17

Paracoccidioidomycosis

Answer 17

Paracoccidioides brasiliensis
Thermal dimorph
Saprobic and parasitic phase
Central and South America: predominately in young adult males - self limiting
Endemic in areas with high humidity, rich vegetation, moderate temperature and acid soil
Infection begins with inhalation or traumatic inoculation

Question 18

Paracoccidioidomycosis pathogenesis

Answer 18

Fungus has protein in cytoplasm which binds only to estrogen and not testosterone and this binding prevents conversion to yeast at 37C
Yeast wall polysaccharides (alpha-glucagon) stimulate granuloma formation

Question 19

Paracoccidioidomycosis clinical findings

Answer 19

Asymptomatic
Latent form:
Variable duration
Re activation leading to disease when host defenses are impaired
Symptomatic:
Adults present with chronic pulmonary disease
Resp issues
Disease progression leads to persistent cough, purulent sputum, chest pain, dyspnea, and fever
Modular lesions in lungs
No treatment leads to dissemination to other organs

Question 20

Paracoccidioidomycosis diagnosis

Answer 20

Direct microscopy:
Sputum, bronchoalveolar lavage, CSF or biopsy of ulcer
Presence of multiple buds distinguishes b/n P. brasiliensis from C. neoformans and B. dermatitidis
Culture
Immunidetection: exoantigen 1, 2, and 3
Serologic testing

Question 21

Paracoccidioidomycosis treatment

Answer 21

Amphotericin B
Ketoconazole
Itraconazole
Sulfanilamides