Pulmonary Fungal Infection 2 Flashcards by Justin Faulkner

What is the most important predisposition for susceptibility to opportunistic mycoses?

Prolonged Neutropenia

Underlying dz–determines severity

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What are the five serotypes of Cryptococcus neoformans and gattii?

Neoformans–A, D and AD

Gattii–B and C

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Where is cryptococcus neoformans found?

Environmental–found worldwide in soil contaminated with bird droppings—PIGEON

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Where is cryptococcus gatti found?

Found in litter under eucalyptus trees

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What is the structure of cryptococcus?

Oval yeast with narrow-based buds and wide polysaccharide capsule

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When is cryptococcus strain pathogenic?

At 37 C

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Is there human-to-human transmission of cryptococcus?

ONLY organ transplantation or needle stick–so in hospital

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What has increased the caseload of cryptococcal meningitis?

Use of steroids
Survival with malignancy
AIDS

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How is cryptococcosis transmitted?

Inhalation–pigeon droppings

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How does cryptococcosis travel through body?

Either using macrophages or as a bare yeast because of thick capsule

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Dissemination of cryptococcosis leads to?

Cryptococcal meningitis with SKIN Nodules

Seen mostly in AIDS pts

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What causes the organ damage seen with C. neoformans?

Tissue distortion from growing yeast

Very little inflammatory response or granuloma formation occurs with neoformans

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What are the virulence factors of cryptococcosis?

Capsule
Melanin in cell wall- antiphagocytic
Phospholipase B–allows tissue invasion

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Why are fever and stiff neck less common with cryptococcosis meningitis?

Little inflammation involved with cryptococcosis infection

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What complicates the dx of cryptococcosis infection?

Blunted inflammatory response–usually means pts present late in dz progression

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What is used for assessment of the CSF with cryptococcosis infection?

India ink stain– observe yeast with wide capsule

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What is used to stain a biopsy of cryptococcosis infection?

Methenamine silver
PAS
Mucicarmine

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How is cryptococcosis cultured?

37C on Sabouraud agar

Will produce melanin in culture

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What is crag in the context of cryptococcosis?

Serology–Latex agglutination for cryptococcal antigen in blood and CSF

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What is Cryptococcomas

Focal neurologic defects

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What is the tx for meningitis or cryptococcoma caused by cryptococcosis infection?

Amphotericin B plus flucytosine for 2 wks followed by 10 wks of fluconazole

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What is the tx for cryptococcosis infection involving the prostate

Fluconazole

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What is the tx for cryptococcosis infection involving the skin and bones?

Amphotericin B

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When is it safe to stop tx for a cryptococcosis infection?

CSF needs to be examined weekly— must have consistently failed cultures to DC tx

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What are the descriptive features of aspergillosis?

Mold--septate hyphae with V-shaped branches

What are the 4 syndromes caused by aspergillosis?

Allergic bronchopulmonary aspergillosis Aspergilloma or colonizing aspergilliosis: fungus ball in lung Chronic necrotizing pulmonary aspergillosis Invasive aspergillosis

What is allergic bronchopulomnary aspergillosis?

HSR to infection of bronchi by aspergillus Seen in asthmatic and CF pts

What is Aspergilloma

Fungus ball formation when aspergillus invades cavitary pulmonary lesions of TB, CF Hemoptysis is seen and can be life-threatening

What is Chronic necrotizing pulmonary aspergillosis?

Seen in immunocompromised pts--invades lungs causing pneumonia with hemoptysis and granulomas (can have hyphae within granuloma) High mortality rate

What is invasive aspergillosis?

Rapidly progressive invasion of blood vessels in severely immunosuppressed pts Involves infarction, hemorrhage, necorsis and is often fatal

What are the Virulence factors of aspergillus?

Gliotoxin--immunosuppressive Toxic metabolites interfere with phagocytosis and opsonization Proteases--involved in tissue invasion

Patient presents with positive skin test for aspergillus allergy and has a history of asthma or CF, coughing up brownish bronchial plugs containing hyphae, has fever, wheezing and pulmonary infiltrates that are NOT responsive to antibiotics and asthma/CF has been worse lately. Xray shows grape cluster of mucus-clogged bronchi. Dx?

Allergic bronchopulmonary aspergillosis

Pt presents with fungus ball in lung on X-ray that changes position when pt sits up. Mass does not invade tissue. A air crescent sign is seen on CT of the lung. Dx?

Aspergilloma or colonizing aspergilliosis

Pt presents with subacute pneumonia that is unresponsive to antibiotics. Pt has a history of COPD and has been on long-term steroid therapy. Has been on empiric tx for TB that has failed. dx?

Chronic pulmonary aspergillosis Usually seen with underlying dz (alcoholism, collagen-vascular dz, chronic granulomatous dz, or COPD) and with long-term corticosteroid therapy

Pt present with Hx of profound immunosuppression and COPD and is on corticosteroid therapy. Pt has fever, cough, dyspnea, pleuritic chest pain, neutropenia and hemoptysis. CT scan shows halo sign--ground glass infiltrate surrounding a nodular density. Dx?

Invasive aspergillosis

How is a culture prepared for aspergillosis and what is seen?

Visualize with silver stains See colonies with radiating chains of conidia that grows fast

What are some defining features of aspergillosis?

Septate hyphae branching at acute angles invading tissue Tissue necrosis Blood vessel invasion High serum levels of glactomannan antigen

What are laboratory findings seen with allergic bronchopulmonary aspergillosis?

High levels of aspergillus-specific IgE and eosinophilia Mucus with degenerating eosinophils and hyphae

What is the tx for allergic bronchopulomnary aspergillosis?

Oral corticosteroids which is what causes the others itraconazole

What is the tx for aspergilloma?

Surgical removal if hemoptysis and oral itraconazole

What is the treatment for invasive or Chronic necrotizing pulmonary aspergillosis?

Voriconazole and/or amphotericin B Decrease immunosuppression if possible High mortality

What are the underlying risk factors for Mucormycosis (Rhizopus) infection?

DM | Neutropenia

How is mucormycosis (Rhizopus) transmitted?

Airborne asexual spores Inhaled or ingested/introduced by trauma Invades tissues of pts with reduced immunity--DM, Burns, Leukemia, IV steroids or TNF blockers, iron overload

What cells are the main host defense against mucormycosis (Rhizopus)?

Neutrophils

What is seen with mucormycosis (Rhizopus) infection when involving rhino cerebral area?

Unilateral retro-orbital HA Facial pain Numbness Fever Progresses to: - Diplopia and visual loss - Reduced consciousness - Black pus - Necrotic eschars

What is seen cutaneously with a mucormycosis (rhizopus) infection?

cellulitis progressing to dermal necrosis and black eschar formation

What is seen on blood work of a patient with mucormycosis (rhizopus) infection?

Neutropenia Diabetic acidosis Iron overload

What is seen on biopsy of mucormycosis (Rhizopus)?

Nonseptate hyphae with broad irregular walls and branches at right angles Vascular invasion and necrosis with neutrophil infiltration

What is seen on a culture of mucormycosis (rhizopus)?

colonies with spores contained in sporangium

What is the tx for mucormycosis (rhizopus) infection?

If dx early tx underlying disorder and amphortericin B and aggressive surgical removal of necrotic tissue Very high mortality rate

What is unique under the microscope about fusarium?

Banana--shaped marcoconidia

What are the virulence factors for fusarium mycology?

Immunosuppressive mycotoxins Collagenases and proteases Ability to adhere to prosthetic material

What are the 3 presentations seen with fusarium?

Mycotoxicosis Immunocompetent local infection Immunosuppressed opportunistic infection

What is seen with mycotoxicosis caused by fusarium?

Widespread bleeding and immunosuppression with secondary sepsis--often fatal

What is seen with immunocompetent local infection caused by fusarium infection?

Seen with burns and contaminated contact lens solution--skin and cornea involved Allergic sinusitis Colonization of prosthetics and catheters

What is the tx for immunocompetent local infection caused by fusarium infection.

Amphotericin B Voriconazole Posaconazole

What are the predispositions exposing pts to an opportunistic infection caused by Fusarium?

Prolonged neutropenia Long-term use of steroids Profound T-cell deficiency (HSCT recipients)

What causes a disseminated fusarium infection and how does it present?

Invasion from sinus or wound site Presentation: -Fungemia with skin lesions that invaded from within the skin!!

What complicates culturing of fusarium?

Grow very easily on media BUT is environmentally ubiquitous so MANY samples and sites are need to differentiate from lab contamination

What is used for the prevention of Fusarium infection?

High-risk pts kept in HEPA filtered rooms at POSITIVE pressure with filtered water supplies and scrubbed-down showers