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I & I Part IV > Endemic Mycoses > Flashcards

Endemic Mycoses Flashcards

1
Q

Endemic fungal infections

A
  • These occur in immunologically normal and impaired hosts
  • May have generally defined geographic endemic zones
  • All are dimorphic
  • Include
  • Histoplasmosis
  • Blastomycosis
  • Sporotrichosis
  • Paracoccidioidomycosis
  • Penicilliosis (Talaromycosis)
  • Coccidioidomycosis
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2
Q

Histoplasmosis

A
  • Most common endemic mycosis in the United States
  • Described by Samuel Darling in Panama in 1906

-originally thought to be Leishmania

• One species associated with human disease

  • Histoplasma capsulatum
  • var capsulatum
  • var duboisii
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3
Q

Histoplasmosis - Mycology

A
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4
Q

Histoplasmosis - Ecology and epidemiology

A
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5
Q

Histoplasmosis - Clinical Disease

A

• Asymptomatic infection

  • 50-85% of all cases

• Acute pulmonary

  • Pneumonia
  • Pericarditis
  • Bob Dylan in 1997
  • Chronic pulmonary
  • Disseminated
  • Fibrosing mediastinitis
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6
Q

Acute Pulmonary Histoplasmosis

A
  • Often associated with a specific exposure
  • Dry cough, fever, fatigue
  • 5% erythema nodosum, myalgias, arthralgias
  • Patchy alveolar infiltrates on chest radiograph
  • Usually self-limited over several weeks
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7
Q

Chronic pulmonary histoplasmosis

A
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8
Q

Disseminated histoplasmosis

A

• Frequently associated with depressed cellular immune function

  • AIDS
  • Chronic course in older men

• Hepatosplenomegaly, lymphadenopathy, weight loss

  • mucous membrane ulcers
  • skin lesions
  • adrenal insufficiency
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9
Q

Histoplasmosis - Fibrosing mediastinitis

A
  • Excessive fibrosis enveloping mediastinal structures
  • Obstruction of vena cava & other structures
  • hemoptysis, dyspnea
  • may mimic nodular sclerosis Hodgkins disease
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10
Q

Histoplasmosis - Diagnosis

A

• Culture

  • growth as mold at 30°C
  • may take 6 weeks
  • DNA probe
  • Histological identification
  • budding yeasts 2-4 µm inside macrophages

• Antigen detection

  • enzyme immunoassay (EIA) for H. capsulatum polysaccharide
  • blood, urine, bronchoalveolar fluid, CSF
    • in >75% of diffuse pneumonia and disseminated disease
  • less likely positive in less severe infection
  • cross-reacts with Blastomyces, Penicillium, Paracoccidioides, Coccidioides
  • Serologic tests
  • complement fixing (CF) and immunodiffusion (ID)
  • yeast & mycelial antigens
  • persist for years
  • most useful for persistent and chronic pneumonia
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11
Q

Histoplasmosis Therapy

A

• Many cases do not require antifungal therapy

  • self-limited pulmonary
  • mediastinal fibrosis
  • pericarditis
  • Symptomatic pulmonary & disseminated diseas - liposomal amphotericin B
  • severe disease
  • itraconazole

• mild to moderate disease

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12
Q

Blastomycosis

A
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13
Q

Blastomycosis - Mycology

A
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14
Q

Blastomycosis - Clinical Presentation

A
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15
Q

Blastomycosis - Diagnosis

A

• Histopathology

  • broad-based budding yeast in tissue

• Culture

  • takes several weeks
  • mold difficult to identify by appearance difficult
  • exoantigen
  • Antibody
  • not useful
  • many cross-reactions
  • Antigen test now available
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16
Q

Blastomycosis - Treatment

A

• Pulmonary disease

  • mild to moderate: itraconazole
  • severe disease: amphotericin B

• Disseminated disease

  • CNS: amphotericin B
  • Other
  • Severe: amphotericin
  • Mild to moderate: itraconazole
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17
Q

Sporotrichosis

A
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18
Q

Sporotrichosis - Clinical Presentation

A

• Chronic subcutaneous suppurating infection

  • pustules
  • ulcers
  • lymphangitic spread

• Pneumonia and osteoarticular infection increasingly reported

  • older male, smoker and alcohol use
19
Q

Sporotrichosis - Diagnosis

A
  • mold usually grows 3-5 days at 30°C

• “daisy” clusters on microscopic examination - histopathology reveals 3-5 µm budding, oval yeasts

  • but rarely seen in human cases;
  • “asteroid bodies” radiating eosinophilic rays
20
Q

Sporotrichosis - Treatment

A

• Lymphocutaneous sporotrichosis

  • itraconazole

• 200 mg oral daily -

saturated solution potassium hydroxide (SSKI)

  • was standard treatment
  • 5 drops TID oral with increasing weekly
  • terbinafine

• 500 mg oral twice daily

  • limited experience
  • hyperthermia
  • may be effective because of thermal intolerance of S. schenckii
  • Pneumonia and osteoarticular disease
  • amphotericin B intravenously
  • itraconazole 200 mg oral twice daily
21
Q

Paracoccidioidomycosis

A
  • Endemic to Brazil
  • Name derived because of initial confusion with coccidioidomycosis
  • also called South American blastomycosis
  • Most cases in older men with heavy tobacco and alcohol use
  • Ulcerated lesions of the nares, oral cavity
  • Due to Paracoccidioides brasiliensis
  • dimorphic
  • yeast-form seen in tissue
  • “steering wheel”
  • Itraconazole primary therapy
22
Q

Penicilliosis (Talaromycosis)

A

• Penicillium marneffei (now called Talaromyces marneffei)

  • isolated from a bamboo rat in Vietnam in 1956
  • named after Hubert Marneffe, director of the Institut Pasteur in Indochina
  • dimorphic

• First non-iatrogenic human case reported in 1973

  • missionary with Hodgkins disease

• With the AIDS epidemic, now a common opportunistic infection in Southeast Asia

  • Thuy Le, M.D., Ph.D, Associate Professor, Duke University
  • M.D. 2002 from University of Arizona
  • Fever, weight loss, papular skin lesions hepatosplenomegaly, lymphadenopathy
23
Q

Penicilliosis (Talaromycosis) - Diagnosis

A
  • On culture, produces a red, diffusable pigment
  • Septate yeast seen on biopsy
24
Q

Penicilliosis (Talaromycosis) - Therapy

A
  • amphotericin B followed by itraconazole has been most commonly used
25
Q

Coccidioidomycosis

A

• Coccidioides is now recognized as two genetically distinct species

  • C. immitis

• mostly confined to the San Joaquin Valley of California

  • C. posadasii

• geographically diverse

  • No clear morphological, biochemical or clinical differences between these two species
26
Q

Life cycle of Coccidioides

A
27
Q

Common presenting symptoms of pulmonary coccidioidomycosis

A
  • Cough
  • Pleuritic chest pain
  • Fever
  • Usually acute (over days)
  • May be difficult to distinguish from community-acquired pneumonia (“CAP”) that is due to bacterial etiology
28
Q

Symptoms suggestive of pulmonary coccidioidomycosis

A
  • Night sweats
  • Fatigue
  • Rash
  • Headache
  • Weight loss
  • Symptoms persisting for weeks
29
Q

Rashes associated with primary pulmonary coccidioidomycosis

A
30
Q

Coccidioidomycosis - Distinctive radiographic features

A
  • Dense infiltrate
  • Upper lobe
  • Associated hilar or mediastinal adenopathy
31
Q

Diffuse or “miliary” pulmonary coccidioidomycosis

A

• Occurs in highly immunocompromised patients

  • presentation of AIDS in coccidioidal endemic region
  • manifestation of fungemia

• May also occur from high inoculum exposure

  • archeology
32
Q

Clinically disseminated coccidioidomycosis

A
  • Occurs in ≤1% of instances
  • Most common sites
  • Skin & soft tissue
  • Bone & joint
  • Meninges
  • Diffuse pulmonary disease

• Generally associated with a lack of specific cellular immune response

33
Q

Cutaneous Coccidioidomycosis

A
34
Q

Vertebral Coccidioidomycosis

A
35
Q

Coccidioidomycosis - Meningitis

A

• Presentation of subacute decreasing mental status, headache

  • One-half present without preexisting pneumonia

• Lymphocytic pleocytosis with hypoglycorrhachia

  • confused with tuberculous meningitis
  • coccidioidal meningitis > tuberculous meningitis in endemic region
  • Universally fatal if untreated
  • Course can be complicated by hydrocephalus
  • despite appropriate antifungal therapy
36
Q

Coccidioidomycosis - Diagnosis Culture

A
37
Q

Coccidioidomycosis - Diagnosis Histology

A
38
Q

Coccidioidomycosis - Diagnosis Direct Examination

A
39
Q

Coccidioidomycosis - Diagnosis Serology

A

•Serology is very commonly used in the diagnosis. While very specific, its sensitivity is not known and it may be negative early in the course of illness. There are a variety of serological tests and interpretation of results is different for each. In patients with disseminated disease, high titers of anti-coccidioidal IgG occur. These decline as the patient improves with therapy.

40
Q

Issues with coccidioidal serology

A

• TP (IgM)

  • False positive results

• latex agglutination (LPA), EIA

  • Titer not prognostically useful
  • Insensitive for diagnosis of meningitis

• CF

  • Elevated titers reflect worsening clinical disease
  • EIA IgG optical density ≠ titer

• Discrepancies between EIA IgG & other methods

  • Concentrating serum may increase diagnostic yield
41
Q

Coccidioidomycosis Treatment

A
  • Most patients will not require any therapy
  • Once started, prolonged therapy (≥12 months) is the rule
  • Relapse occurs in 15 - 30%
  • Meningitis appears to be rarely if ever cured
  • Potential for teratogenicity in women with high-dose azoles
42
Q

Indications for treatment of primary coccidioidal pneumonia

A
  • Weight loss >10%
  • Night sweats for > 3 weeks
  • Extensive pneumonia
  • Greater than 50% of one lung
  • Both lungs
  • Coccidioidal CF > 1:16
  • Inability to work
  • Persistence of symptoms for > 2 months
43
Q

Treatment of non-meningeal disseminated infection

A
  • Amphotericin B ± triazole for initial therapy in severly ill patients
  • Amphotericin B can then be tapered and patient left on long-term triazole
  • Length of therapy unclear
  • low or undetectable CF titer
  • evidence of cellular immunity
44
Q

Treatment of meningeal disease

A
  • Fluconazole or itraconazole
  • Follow for development of hydrocephalus
  • Failure
  • newer triazoles
  • intrathecal amphotericin B

• Treatment should be life-long

I & I Part IV (13 decks)

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