Micro - Mycology

Question 1

Most fungal spores are _____ (sexual/asexual).

Answer 1

Asexual

Question 2

Asexual fungal spores are also known as what?

Answer 2

Conidia

Question 3

A gardener has an arm pustule with ascending lymphangitis. You biopsy it and see a fungus. What is it and how do you treat it?

Answer 3

Sporotrichosis (“rose gardener’s disease”) caused by Sporothrix schenckii;
treatment is itraconazole or potassium iodide

Question 4

A girl has hyperpigmented skin patches. You biopsy the skin and see “spaghetti
and meatballs” on KOH prep. Diagnosis?

Answer 4

Tinea versicolor, caused by Malassezia furfur fungus

Question 5

Name two systemic mycoses that are transmitted by inhalation of asexual spores.

Answer 5

Coccidioidomycosis and histoplasmosis

Question 6

What do histoplasmosis, paracoccidioidomycosis, and blastomycosis have in
common?

Answer 6

They are all systemic mycoses caused by dimorphic fungi (mold in soil, but yeast 
in tissue (remember: mold = cold; heat = yeast)

Question 7

Histoplasmosis is endemic in what area of the United States?

Answer 7

The Mississippi and Ohio River valleys

Question 8

Histoplasmosis is most commonly transmitted via what substance?

Answer 8

Bird or bat droppings

Question 9

Blastomycosis is endemic in what areas of the United States?

Answer 9

The states east of the Mississippi River; it is also common in Central America

Question 10

What is the characteristic microscopic appearance of blastomycosis?

Answer 10

Big, broad-based budding

Question 11

A 40-year-old male from Central America presents with dyspnea and
granulomatous skin nodules. What diagnosis do you expect?

Answer 11

Blastomycosis

Question 12

Coccidioidomycosis is endemic in what area of the United States?

Answer 12

The southwestern United States, including California

Question 13

What are two colloquial names for disease caused by coccidioidomycosis?

Answer 13

San Joaquin Valley fever and desert valley fever (desert bumps)

Question 14

Paracoccidioidomycosis is endemic in what area?

Answer 14

Latin America

Question 15

The yeast that causes paracoccidioidomycosis has what appearance on
microscopy?

Answer 15

The “captains wheel” appearance

Question 16

What is the treatment of choice for local infection with dimorphic fungi?

Answer 16

Fluconazole or ketoconazole

Question 17

What is the treatment of choice for systemic infection with dimorphic fungi?

Answer 17

Amphotericin B

Question 18

Systemic mycoses can mimic which other infectious disease with granuloma
formation?

Answer 18

Tuberculosis

Question 19

Histoplasmosis has what appearance under microscopy?

Answer 19

Macrophages filled with yeast (remember: Histo Hides in macrophages)

Question 20

All systemic mycoses can cause what type of illness?

Answer 20

Pneumonia that can disseminate

Question 21

In addition to pneumonia, what other illnesses can coccidioidomycosis cause?

Answer 21

Meningitis with dissemination to skin and bone

Question 22

Describe the sizes of the four dimorphic fungi in relation to the size of a red blood
cell.

Answer 22

Histoplasmosis: smaller; blastomycosis: same; coccidioidomycosis and
paracoccidioidomycosis: larger

Question 23

Tinea versicolor is caused by what organism?

Answer 23

Malassezia furfur

Question 24

An athlete presents with hypopigmented macules on her upper back after a summer
of exercising. What is your diagnosis and what is the treatment?

Answer 24

Tinea versicolor; treat with topical miconazole and selenium sulfide

Question 25

What are the characteristic skin lesions of tinea pedis, cruris, corporis, and capitis?

Answer 25

Pruritic lesions with central clearing that resembles a ring (the infection is colloquially known as ringworm)

Question 26

Tinea pedis, tinea cruris, tinea corporis, and tinea capitis are caused by what organisms?

Answer 26

Dermatophytes (ie, Microsporum, Trichophyton, Epidermophyton)

Question 27

What animals are commonly reservoirs for Microsporum?

Answer 27

House pets

Question 28

What is the typical microscopic appearance of the agent causing tinea versicolor on KOH prep?

Answer 28

"Spaghetti and meatballs" (Malassezia furfur)

Question 29

Pets infected with Microsporum can be treated with what?

Answer 29

Topical azoles

Question 30

What causes hypopigmented patches of tinea versicolor?

Answer 30

Degradation of lipids by Malassezia furfur, producing acids that damage melanocytes

Question 31

Dermatophytes have what microscopic appearance in KOH prep?

Answer 31

Visible mold hyphae

Question 32

What four patient populations commonly contract oral and esophageal thrush as a result of Candida infection?

Answer 32

Neonates, steroid users, patients with diabetes, and patients with AIDS

Question 33

How is Candida albicans diagnosed microscopically?

Answer 33

Yeast with pseudohyphae in culture, germ tubes at body temperature

Question 34

Vulvovaginitis caused by Candida albicans commonly occurs in what types of patients?

Answer 34

Women with a high vaginal pH, diabetes, and/or a recent history of antibiotic use

Question 35

What three diseases are caused by Aspergillus fumigatus?

Answer 35

Allergic bronchopulmonary aspergillosis, lung cavity aspergilloma ("fungus ball"), and invasive aspergillosis

Question 36

Aspergillus fumigatus is a ____ (mold/yeast/dimorphic) with a _____ branching pattern and ____ hyphae.

Answer 36

Mold (not dimorphic); V-shaped (remember: Acute Angles in Aspergillus); septate

Question 37

Cryptococcus neoformanscauses what two diseases?

Answer 37

Cryptococcosis and cryptococcal meningitis

Question 38

Which two tests can be used to diagnose cryptococcal infection?

Answer 38

India ink stain and latex agglutination test

Question 39

Where can the heavily encapsulated yeast of Cryptococcus neoformans be found in nature?

Answer 39

Soil and pigeon droppings

Question 40

On what medium is Cryptococcus neoformanscultured?

Answer 40

Sabouraud’s agar

Question 41

What stain can be used to visualize Cryptococcus neoformans?

Answer 41

India Ink

Question 42

How are Mucorand Rhizopus species morphologically different | from Aspergillus species?

Answer 42

Mucor and Rhizopus have irregular, nonseptate hyphae with wide-angle branching, while Aspergillus have more uniform septate hyphae with acute-angle branching

Question 43

A patient exposed to bat droppings develops pneumonia. You see macrophages filled with yeast on microscopy. Diagnosis?

Answer 43

Histoplasmosis

Question 44

A pigeon keeper on immunosuppressants develops meningitis. You sample the cerebrospinal fluid and see heavily encapsulated yeast. Diagnosis?

Answer 44

Cryptococcus neoformans infection