L31: Fungal Infections of the Respiratory Tract

Question 1

Zygomycoses (mucormycosis)

Answer 1

Group of uncommon but potentially fatal infection caused by fungi belonging to Zygomycetes class; infection rare in normal healthy individuals but can occur in people with immunosuppression, diabetes, or burns

Question 2

3 main genera of zygomycetes

Answer 2

1. Rhizopus
2. Absidia
3. Mucor
   - -All have non-septate hyphae

Question 3

Rhinocerebral zygomycosis

Answer 3

Most common form of zygomycosis, primarily diabetic patients, originates in sinuses

Question 4

Where else can zygomycotic infections occur?

Answer 4

Zygomycotic infections of the lungs, skin and GI tract can occur in immunosuppressed or burn patients

Question 5

Diagnosis of zygomycoses

Answer 5

In tissue section, broad aseptate hyphae are frequently observed branching at right angles

Question 6

Treatment of zygomycoses

Answer 6

Amphotericin B

Question 7

What causes candidiasis?

Answer 7

Yeast of the genus Candida (mostly Candida albicans)

Question 8

Candida albicans

Answer 8

Considered normal flora and present in environment, exists in yeast, pseudohyphal, and hyphal forms

Question 9

Oral candidasis (thrush)

Answer 9

Seen in infants, adults after steroids/antibiotics, AIDS patients

Question 10

How does thrush present?

Answer 10

Diffuse erythema and white cheesy patches on the surface of the buccal mucosa, throat, tongue, and gums; plaques can be scraped or wiped away revealing lesion

Question 11

Diagnosis of thrush

Answer 11

Direct observation of Candida in clinical material (generally don’t need cultures)

Question 12

Treatment of thrush

Answer 12

Oral formulations (mouth washes or lozenges) of nystatin and azole compounds

Question 13

Basic info about systemic mycoses

Answer 13

ALL present initially as pulmonary infection – diverse group of presentations, not opportunistic, found in environment, acquired by inhalation of fungal elements

Question 14

Systemic mycoses that are dimorphic fungi (4 types)

Answer 14

Histoplasma capsulatum, Blastomyces dermatitidis, Paracoccidioides brasiliensis, Coccidioides immitis

Question 15

Systemic mycoses that is encapsulated yeast

Answer 15

Cryptococcus neoformans (also has a worldwide distribution)

Question 16

Regional trends of histoplasmosis

Answer 16

Most prevalent in distinct regions of North/Central America, endemic in Mississippi and Ohio River valleys

Question 17

Cause of histoplasmosis

Answer 17

Histoplasma capsulatum; found in soil under humid climate conditions, infection acquired by inhalation of micro- or macroconidia from environment

Question 18

Histoplasmosis transmission

Answer 18

From bird/bat droppings, gets inhaled and can survive in macrophages (converts to yeast form and replicates there) – normally immune system takes care of it on its own

Question 19

Pulmonary histoplasmosis

Answer 19

Mild flu-like illness with dry cough, fever, fatigue – can sometimes cause small calcifications on CXR

Question 20

Chronic pulmonary and disseminated histoplasmosis

Answer 20

Typically occur in immunocompromised individuals – experience fever, night sweats, anorexia, weight loss, fatigue and respiratory symptoms – also hepatomegaly, splenomegaly, and lymphadenopathy

Question 21

Diagnosis of histoplasmosis

Answer 21

Direct observation of organisms (yeast form) in tissues or clinical samples, cultivation of organisms from clinical samples, serology (detected Ag or Ab)

Question 22

Treatment of histoplasmosis

Answer 22

Amphotericin B (but AIDS patients/immunosuppressed individuals need lifelong suppressive therapy with azoles)

Question 23

Regional trends of blastomycosis

Answer 23

Endemic in Ohio and Mississippi river valley and a little bit in Missouri and Arkansas river basins

Question 24

Cause of blastomycosis

Answer 24

Blastomyces dermatitidis (very large with very thick cell walls)

Question 25

Disease process of blastomycosis

Answer 25

Pulmonary disease with potential to disseminate, acquired through inhalation of spores from environment, normally asymptomatic

Question 26

Symptoms of acute blastomycosis

Answer 26

Cough, fever, chills, arthralgia, myalgia (may also mimic bacterial pneumonia with chest pain and sputum)

Question 27

Symptoms of chronic pulmonary blastomycosis

Answer 27

Cough, fever, night sweats, weight loss, sputum production (mimics TB)

Question 28

Symptoms of disseminated disease

Answer 28

Skin lesions and bone infections -- must be treated

Question 29

Diagnosis of blastomycosis

Answer 29

Observation of distinct yeast forms in sputum or biopsy material

Question 30

Treatment of blastomycosis

Answer 30

Amphotericin B, azoles for uncomplicated pulmonary disease (if treated at all)

Question 31

Regional trends of paracoccidioidomycosis

Answer 31

Limited to tropical regions of South and Central America (90% of disease occurs in men)

Question 32

Cause of paracoccidioidomycosis

Answer 32

Paracoccidioides brasiliensis; forms ship's wheel or Mickey Mouse ears

Question 33

Disease process of paracoccidioidomycosis

Answer 33

Most infections asymptomatic, pulmonary infection and disseminated disease possible

Question 34

Diagnosis of paracoccidioidomycosis

Answer 34

Observation, cultivation, and serology

Question 35

Regional trends of coccidioidomycosis

Answer 35

Throughout Western hemisphere, highly endemic in San Joaquin Valley (CA) and southern Arizona -- follow drought-rain-drought pattern

Question 36

Life cycle of coccidioidomycosis

Answer 36

Arthrocanidia (big hyphae) break in pieces and blow around; once inside forms spherules (look like bags of yeast) inside body

Question 37

Disease process of coccidioidomycosis

Answer 37

Most individuals asymptomatic, pulmonary disease can be mild to moderate influenza-like syndrome -- normally spontaneously resolves

Question 38

Disseminated disease in coccidioidomycosis

Answer 38

Rare, develops within one year of infection, infects bones, joints, skin, and CNS ("desert rheumatism")

Question 39

Coccidial meningitis

Answer 39

Develops slowly with increasing headache, fever, stiff neck, and other neurological signs

Question 40

Diagnosis of coccidioidomycosis

Answer 40

Observation (spherule!), cultivation, serology

Question 41

Treatment of coccidioidomycosis

Answer 41

Azole or Amphotericin B

Question 42

Cryptococcosis basics

Answer 42

Found throughout the world, leading form of fungal meningitis

Question 43

Cause of cryptococcosis

Answer 43

Cryptococcus neoformans (NOT DIMORPHIC, encapsulated yeast), can be isolated from environment -- comes from pigeon/bird droppings

Question 44

Fungal meningitis

Answer 44

Most commonly recognized form of cryptococcal infection, develops slowly and causes intermittent bouts of headache, irritability, dizziness and other CNS -- life-threatening (common in AIDS patients)

Question 45

Diagnosis of cryptococcosis

Answer 45

India ink stain, cultivation, serology

Question 46

Pneumocystis jiroveci (carinii) pneumonia (PCP)

Answer 46

Highly lethal, occurs mostly in immunocompromised (AIDS)

Question 47

P. jiroveci

Answer 47

Eukaryotic organism, related to fungi -- not much known about it

Question 48

Presentation of PCP

Answer 48

Initiated through inhalation of cysts, asymptomatic infection in healthy individuals but when symptomatic = dyspnea, nonproductive cough, fever

Question 49

Diagnosis of PCP

Answer 49

Identification of organisms (trophozoite, sporozoites, cysts) in clinical material

Question 50

Basics of aspergillosis

Answer 50

Aspergillus (many diff. species), rarely pathogenic in normal individual, wide range of clinical disease in immunocompromised individuals

Question 51

2 main fungal causes of aspergillosis

Answer 51

A. fumigatus and A. flavus -- not dimorphic, septic hyphae that grow inside our tissues

Question 52

Acute pulmonary infection (aspergillosis)

Answer 52

Colonization of pre-existing lung lesions with "fungus balls" that are typically unilateral and asymptomatic

Question 53

Invasive/disseminated/systemic infection

Answer 53

Occurs primarily in leukemia, neutropenia, or organ/marrow transplant patients, often fatal if not detected