Endemic mycoses

Question 1

the meaning of dimorphic as it relates to the endemic mycoses

Answer 1

Can grow as either a test of a mould depending on environment (Yeast at 37 and mould in lab)

Question 2

Epidemiology of coccidioidomycosis

Answer 2

Endemic to hot dry places in western hemisphere - in US, California, Arizona, N Mexico, Texas. Some in mexico, Central and south america

Question 3

Mycology of coccidioidomycosis

Answer 3

Exists as mycelium (mould), but when spores inhaled it forms spherule (a multinucleated structure)

Question 4

Symptoms of coccidioidomycosis

Answer 4

Many have no symptoms or mild URTI. Others have influenza-like illness 3 weeks after exposure (cough, fever, drenching night sweats, pleuritic chest pain, or arthralgia). Often resolves w/o Tx, but can develop severe pneumonia and spread to skin, bone/joints, meningitis

Question 5

Diagnosis of coccidioidomycosis

Answer 5

Biopsy is best, DNA probe, maybe ABs

Question 6

Therapy for coccidioidomycosis

Answer 6

Amphoteirriicin B (for worst case), fuconazole, Itraconazole

Question 7

Epidemiology of histoplasmosis

Answer 7

Most endemic in the Mississippi and Ohio river valleys, Also parts of Australia, Africa, SE Asia, and South America, soil fungus that favours moderate climate & humidity. Found in bird and bat poop enhance growth

Question 8

Mycology of histoplasmosis

Answer 8

H. capsulatum exists in 2 forms – mycelial phase (present at ambient temperature) and the yeast phase (present at 37ºC or higher)

Question 9

Pathogenesis of histoplasmosis

Answer 9

Microconidia settle into the alveoli and are engulfed by neutrophils and macrophages; once intracellular mycelia are converted to the yeast form; migrate to lymph nodes and than to distant organs that are rich in macrophages (liver and spleen)

Question 10

Diagnosis of histoplasmosis

Answer 10

Most have mild flu-like illness. Severity depends on inoculum. Acute and possibly many complications. Fungal stain, or AB (slow)

Question 11

Acute histoplasmosis

Answer 11

symptoms include fever, chills, non-productive cough, chest pain (substernal related to enlargement of mediastinal/hilar lymph nodes, pleuritic pain is uncommon), malaise, myalgia, etc. CXR findings usually shows hilar/mediastinal lymphadenopathy (LN) or patchy reticulonodular infiltrates. Respiratory failure and death may ensue

Question 12

Complications of histoplasmosis

Answer 12

Massive enlargement of the mediastinal LNs; Histoplasmoma (lesion forms calcified mass); Fibrosing Mediastinitis (can lead to scarring and airway obstruction)

Question 13

Disseminated histoplasmosis

Answer 13

acute and chronic progressive disseminated histoplasmosis. Complications – CNS involvement, endocarditis, adrenal involvement. Acute is 100% fatal if untreated

Question 14

Therapy for histoplasmosis

Answer 14

bad disease use Amphotericin B then itraconazole (itraconazole for mild disease too)

Question 15

Epidemiology of blastomycosis

Answer 15

States along Ohio and Mississippi river basins (incl Manitoba), States/provinces by great lakes and St Lawrence. Parts of Africa, India, Isreal

Question 16

Mycology of blastomycosis

Answer 16

Blastomyces dermatitidis – grows as a mycelial form at room temperature and as yeast form at 37C. Inhale conidia, then Conidia that escape the host defenses are rapidly converted to the yeast form – resistant to phagocytosis

Question 17

Diagnosis of blastomycosis

Answer 17

Non-specific symptoms, usually non-productive cough. Chest Xray: some low things initially. Identify the fungus in smear or culture from tissue or exudates (culture takes 2-4 weeks of incubation). Serology weak

Question 18

Secondary infections to blastomycosis

Answer 18

Pulmonary infection: like chronic pneumonia; cutaneous: seeding through blood, cause lesions that look like skin cancer or ulcers, no lymphadenopathy; subcutaneous; bone/joint; genitourinary; CNS

Question 19

Therapy of blastomycosis

Answer 19

All cases need to be treated! Ketoconazole or itraconazole in immunocompetent patients, Amphotericin B for severely immunocompromised

Question 20

Important reminders when dealing with endemic mycoses

Answer 20

You need to ask about travel history a lot!