Respiratory Fungi Flashcards

Question

Paracoccidioides brasiliensis Characteristics

Answer 1

* Causes **South American Blastomycosis** * Morphology ⇒ dimorphic * **Septate hyphae** @ 25°C * **Yeast** form grow in vivo @ 37°C * Multiple daughter cells off a single parent cell connected by a thin isthmus ⇒ **blastoconidia** * Seen in tissue and can be grown in culture * **"Pilot wheel" morphology** seen w/ GMS stain or H&E in tissue

Answer 2

* Major systemic mycoses in **Latin America** \> **Central America** * **Highest incidence in Brazil** * Mold form grows in areas of high humidity, rich vegetation, and acidic soil * **Esp. along river banks in the Amazon** * **Common in rural areas** * Children frequently infected but asymptomatic * **Disease common in men 30-50 y/o**

Answer 3

**Inhalation or traumatic inoculation of conidia.** Most have contact with soil.

Answer 4

* **Primary disease** * Usually asymptomatic or self-limiting * **Adults** ⇒ _primary or reactivation disease_ * **Chronic pulmonary disease** * Productive cough, weight loss, fever * **Mucocutaneous forms** * **Juvenile form** * Flu-like, lymphadenopathy, hepatosplenomegaly * **Disseminated form** * Young children and immunocompromised

Answer 5

* **Demonstrate yeast form in tissue or sputum** * **"Pilot wheel"** ⇒ yeast * Don't confuse with tuberculate macroconidia of Histoplasma ⇒ spores * These won't be found in tissue or sputum samples * Organisms grown in **culture** need biosafety cabinet * **Serology** ⇒ evaluate response to treatment

Answer 6

**Itraconazole for 6 months.** Severe infections may require Amphotericin B.

Answer 7

* Class **⇒ Zygomycetes aka Mucormycetes** * Order **⇒ Mucorales** * Genera ⇒ **Rhizopus**, **Mucor** * Causes rare, sporadic disease worldwide * When they do occur ⇒ **acute and rapidly progressive** * Mortality rates of 70-100%

Answer 8

"Mucormycetes" * Cause **Mucormycosis** * **Molds that grow rapidly** * Morphology * **Broad hyphae w/ few or no septa** * Asexual spores contained in sporangium ⇒ **sporangiospores** * Root-like structure called **rhizoids**

Answer 9

* Ubiquitous in soil and decaying matter worldwide * **Transmission via spores** * **Inhalation, ingestion, or contamination of wounds** * **Nosocomial spread may occur through HVAC systems** * Esp. near construction sites * Hospital outbreaks associated w/ contaminated dressings/tongue depressors * Causes **invasive zygomycosis** in immunocompromised pts and diabetics

Answer 10

* Organ or BM transplant recipient * Diabetic ketoacidosis * Renal failure * Hematologic malignancy * Neutropenia

Answer 11

* **Pulmonary zygomycosis** * Primary infection in neutropenic pts * Pulmonary invasion, infarcts in pulmonary vessels, and hemorrhage * **Rhinocerebral zygomycosis** * Invasive infection * Starts in nasal cavity, sinuses, or orbit * Extends into face and CNS * Most common in DKA and hematologic malignancy * **Cutaneous zygomycosis** * Primary or secondary * Nodular with ecchymotic center

Answer 12

* **Angioinvasive** * Similar to aspergillus infection * **Tissue and vessel infarction** * **Dissemination** * May cause disease in multiple organ systems * **Cutaneous manifestations** from invasive infection or following traumatic injury

Answer 13

* Tissue biopsy for direct microscopy and culture * Stain with **KOH w/ calcofluor white** * **See broad irregularly branched, twisted or folded hypae w/ few septa** * Culture is frequently negative

Answer 14

* **Amphotericin B** * **Surgical debridement** * Correct underlying condition * Mortality high (50%)

Answer 15

* ***Aspergillus fumigatus*** and ***Aspergillus flavus*** * Most commonly associated with **invasive disease** * Opportunistic fungi * Disease usually associated with **severe neutropenia** * **Found ubiquitously** in the environment * Infection is acquired exogenously

Answer 16

* Exist as **molds** * Composed of **septate hyphae** * Branches @ **45° angles** ⇒ _dichotomous branching_ * Characteristic of Aspergillus * Reproduce **asexually** by **conidiaphore formation**

Answer 17

**Spread by inhalation of conidiaspores** No person to person transmission

Answer 18

* **Seen in people with chronic asthma or CF** * Symptoms * **Episodic wheezing, fever, eosinophilia** * **Transient pulmonary infiltrates** * May become severe with age * Can lead to fibrosis

Answer 19

* **Usually seen in those with underlying lung diease** * Particularly those with **pre-existing cavities** in the lung * **Non-allergic colonization** * Chronic process with development of pathological changes in the lung * Formation of Aspergillus containing granulomas * Causes **"fungus ball"** formations on CXR * Granulomas must be surgically removed + antifulgal medications

Answer 20

* **Only in immunocompromised individuals** * Risk factor ⇒ neutropenia * May involve **pulmonary, sinus, cerebral, or cutaneous sites** * Pathogenesis involves **_angioinvasion_**, thrombosis, and dissemination to other organs * Damage caused by **tissue infarcts, hemorrhage, and necrosis**

Answer 21

* **Gomeri silver stain** of tissue sections * ID by dichotomously branched (45° angle) septate hyphae * Isolation in culture on **Sabouraud's Dextrose Agar (SDA)** * _Allergic aspergillosis_ * Elevated specific IgE * Eosinophilia * Positive skin test (Type I) to Aspergillus Ag

Answer 22

* Conidia (inhaled) ⇒ **MΦ** * Hyphae ⇒ **PMNs** * Line up along hyphal walls and secrete lysosomal enzymes * Patrol blood vessels * Aspergillus is an angioinvasive organism * Neutropenia is the #1 risk factor for invasive aspergillosis

Answer 23

**Amphotericin B** for invasive aspergilliosis Surgical removal of aspergilloma