Deck 27: Medically Significant Fungi

Question 1

A young man notices a darkened area of skin on the palm of his hand.It seems to be increasing in size over the past 2 weeks.His health care provider collects a skin scraping for microscopic examination, which shows septate hyphal elements and budding cells.This organism is most likely:

A)Malassezia furfur.
B)Mucor spp.
C)Hortaea werneckii.
D)Microsporum canis.

Answer 1

C
Tinea nigra, characterized by brown to black nonscaly macules that occur most often on the palms of the hands and soles of the feet, is caused by H.werneckii.The disease is endemic in the tropical areas of Central and South America, Africa, and Asia.Diagnosis of tinea nigra can be made by direct examination of skin scrapings placed in 10% to 20% KOH.Microscopic examination shows septate hyphal elements and budding cells.CDC PHIL #4206

Question 2

A patient with thickened and discolored nails was diagnosed with onychomycosis.A scraping of the nail was sent for culture.Microscopic analysis of the mold colony growth revealed the following morphology.The most likely identity of this organism is:

A)Microsporum canis.
B)Sporothrix schenckii.
C)Aspergillus fumigatus.
D)Trichophyton mentagrophytes.

Answer 2

D
Onychomycosis, infection of the nails, is most often caused by dermatophytes but also may be the result of infection by other fungi.Nails become thick, discolored, and flakey.Some common agents that infect the nails are Trichophyton rubrum, T.mentagrophytes, and T.tonsurans, as well as Epidermophyton floccosum.Trichophyton mentagrophytes makes both microconidia and macroconidia.Microconidia are primarily globose but may appear tear-shaped.Microconidia are found primarily in clusters described as grapelike or "engrape." Macroconidia are thin walled, smooth, and cigar shaped, with four to five cells separated by parallel cross walls.CDC PHIL # 15105

Question 3

A patient with very pale patches on his arms and legs is examined at his physician's office.His physician orders a fungal culture.The fungus shows a spaghetti-and-meatball appearance on the direct smear.What organism is it?

A)Microsporum canis
B)Malassezia furfur
C)Trichophyton rubrum
D)Epidermophyton floccosum

Answer 3

B
Microscopic examination of the direct smear in potassium hydroxide (KOH) preparations reveals budding yeasts, approximately 4 to 8 mm, along with septate, sometimes branched, hyphal elements.This microscopic appearance has gained M.furfur the term spaghetti and meatballs fungus.

Question 4

A bone marrow transplant patient develops an abrupt fever with respiratory distress.Despite treatment with antifungal medications, the patient dies on the fifth day.The following organism was isolated from both sputum and blood cultures.Identify the organism shown below.

A)Rhizopus spp.
B)Mucor spp.
C)Histoplasma capsulatum
D)Aspergillus spp.

Question 5

The following organism is isolated from a case of tinea capitis.The organism grew rapidly producing tan mold colonies.This organism is most likely:

A)Trichophyton rubrum.
B)Epidermophyton audouinii.
C)Fonsecaea compacta.
D)Microsporum gypseum.

Question 6

After returning from a vacation trip to the Amazon River delta in Brazil, a man notices a white dirtlike substance on his axilla hair that does not wash off in the shower.His health care provider samples the hairs and sends them to the laboratory for culture.Straw-colored yeastlike colonies show the following microscopic morphology.This is most consistent with an identification of:

A)Malassezia furfur.
B)Trichosporon spp.
C)Microsporum audouinii.
D)Trichophyton rubrum.

Question 7

The following organism was isolated from an immunocompetent patient with chronic sinusitis.This organism is most likely:

A)Mucor spp.
B)Rhizopus spp.
C)Alternaria spp.
D)Curvularia spp.

Question 8

This organism was isolated from a diabetic patient with a sinus infection.The mold was extremely fast growing with a dirty white surface.Microscopic observation revealed wide aseptate hyphae without rhizoids.This organism is most likely:

A)Mucor spp.
B)Microsporum spp.
C)Sporothrix schenckii.
D)Malassezia furfur.

Question 9

What is the causative agent of black piedra?

A)Microsporum canis
B)Trichosporon beigelii
C)Piedraia hortae
D)Sporothrix schenckii

Question 10

The following organism was isolated from the sputum culture of a cancer chemotherapy patient.This organism is most likely:

A)Mucor spp.
B)Penicillium spp.
C)Geotrichum spp.
D)Alternaria spp.

Question 11

A patient returning from a trip to tropical Africa comes to his physician noting scaly patches of skin along the waistband, which are lighter in color than his normal skin.A skin scraping reveals budding yeast and short septate hyphal elements, with some branching present.This organism, shown below, is most likely:

A)Malassezia furfur.
B)Trichophyton schoenleinii.
C)Microsporum audouinii.
D)Trichophyton rubrum.

Question 12

A recreational cave explorer develops a productive cough and fever.A sputum culture is sent to the laboratory for bacterial, fungal, and mycobacterial cultures.A white mold colony develops on Sabouraud's agar after 5 days at 22° C.Identify the organism shown below.

A)Histoplasma capsulatum
B)Toxoplasma gondii
C)Microsporum tonsurus
D)Paracoccidioides brasiliensis

Question 13

A young boy develops itchy, dry scaly lesions on his leg with a raised, red, outer edge.A culture of the lesion reveals the following organism in a lactophenol cotton blue stain.This organism is most likely:

A)Trichophyton spp.
B)Mucor spp.
C)Microsporum canis.
D)Blastomyces dermatitidis.

Question 14

A student working for the summer at a plant nursery has a nodular lesion on his forearm that develops a draining tract.The following organism is isolated from the culture at 22C.Identify the organism shown below.

A)Trichosporon boydii
B)Sporothrix schenckii
C)Trichophyton rubrum
D)Microsporum canis

Question 15

A patient who wears long-term contact lenses comes to her physician after noting a small spot on her cornea.Collection of the lesion for culture produced a fast-growing mold with a slight pink color on the surface.Microscopic review showed the following organism.This organism is most likely:

A)Sporothrix schenckii.
B)Fusarium spp.
C)Mucor spp.
D)Geotrichum spp.

Question 16

What is the causative agent of tinea nigra?

A)Microsporum canis
B)Trichosporon beigelii
C)Piedraia hortae
D)Hortaea werneckii

Question 17

A graduate student returning from a month-long fieldwork experience in South America develops a dark nodular lesion on his left hand.Microscopic examination of the nodule reveals dark, coinlike inclusions.The following organism grows in culture.This organism is most likely:

A)Cladosporium spp.
B)Candida spp.
C)Coccidioides immitis.
D)Cryptococcus neoformans.

Question 18

A Seattle woman with HIV complains of headaches and also displays some memory loss.Because of her history, the physician collects cerebrospinal fluid (CSF) and sends it to the laboratory for analysis.The following image is seen using India ink stain.What is the most likely identification of this organism?

A)Coccidioides immitis
B)Blastomyces dermatitidis
C)Cryptococcus gattii
D)Candida albicans

Question 19

This organism was isolated from a sinus aspirate of a patient with chronic sinusitis and respiratory allergies.Identify the organism shown below.

A)Candida albicans
B)Alternaria spp.
C)Mucor spp.
D)Pseudallescheria boydii

Question 20

All of the following are examples of dimorphic fungi except:

A)Candida albicans.
B)Coccidioides immitis.
C)Histoplasma capsulatum.
D)Sporothrix schenckii.

Question 21

All of the following organisms cause cutaneous mycoses except:

A)Sporothrix schenckii.
B)Trichophyton beigelii.
C)Microsporum canis.
D)Epidermophyton floccosum.

Question 22

For potassium hydroxide (KOH) to work properly, what is done to speed up the dissolution of the keratin and skin layers?

A)Mix gently.
B)Let the slide sit for 30 minutes before reading.
C)Heat gently, then cool.
D)Let sit under an ultraviolet light for 20 minutes.

Question 23

What organism is found in the San Joaquin Valley region of California?

A)Sporothrix schenckii
B)Penicillium marneffei
C)Coccidioides immitis
D)Paracoccidioides brasiliensis

Question 24

What organism frequently presents in fungus balls?

A)Fonsecaea compacta
B)Penicillium marneffei
C)F.pedrosoi
D)Aspergillus fumigatus

Question 25

Chromoblastomycosis is caused by all the following organisms except:

A)Fonsecaea compacta.
B)Penicillium marneffei.
C)Fonsecaea pedrosoi.
D)Phialophora verrucosa.

Question 26

What organism is one of the primary opportunistic infections in AIDS patients?

A)Pneumocystis jirovecii
B)Hortaea werneckii
C)Coccidioides immitis
D)Paracoccidioides brasiliensis