Question 1

Identify the following:

Accepted Answer

This species makes both microconidia and macroconidia.Microconidia are primarily globose but may appear tear-shaped and measure 2.5 to 4 mm.Microconidia are primarily found 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.These conidia measure about 7 mm by 20 to 50 mm and are produced singly on undifferentiated hyphae.CDC PHIL # 3213

Question 2

Identify the following:

Accepted Answer

As with other Zygomycetes,Mucor has been implicated in rhinocerebral zygomycosis in addition to disseminated disease.Sporangiospores are formed in sporangia on erect sporangiophores.Rhizoids,typical of some Zygomycetes,are not found in Mucor.The sporangia frequently remain intact,as opposed to Rhizopus spp.,in which the sporangia typically collapse.CDC PHIL # 3961

Question 3

Identify the following:

Accepted Answer

The fusiform,moderately thick-walled conidia measure 8 to 15 mm by 25 to 60 mm and may have as many as six cells.In some isolates,the distal end of the macroconidium may bear a thin,filamentous tail.Abundant macroconidia and microconidia produced by most isolates of this species result in a powdery,granular appearance on colony surfaces.CDC PHIL # 3939

Question 4

Identify the following:

Accepted Answer

Curvularia isolates are most often implicated in chronic sinusitis in immunocompetent patients.Multicelled conidia are produced on sympodial conidiophores.This genus is easier to identify because of the frequently crescent-shaped conidia with three to five cells of unequal size,with an enlarged central cell.CDC PHIL 4512

Question 5

All of the following are examples of dimorphic fungi EXCEPT:

Accepted Answer

These dimorphic fungi include a mould phase and either a yeast or spherule phase.The yeast or tissue state is seen in vivo or when the organism is grown at 37° C with increased CO₂.The mould phase is seen when the organism is grown at room temperature.Thermally dimorphic fungal species associated with human disease include Blastomyces dermatitidis,C.immitis,H.capsulatum var.capsulatum,Paracoccidioides brasiliensis,S.schenckii,and Penicillium marneffei.

Question 6

Identify the following:

Accepted Answer

Geotrichum has been implicated in pulmonary disease in immunocompromised patients.Microscopic evaluation reveals abundant arthroconidia formed from the vegetative hypha that occur either single or branched.CDC PHIL #3056

Question 7

Identify the following:

Accepted Answer

The M.furfur complex causes tinea versicolor,a disease characterized by patchy lesions or scaling of varying pigmentation.M.furfur may be identified by visualizing skin scrapings from characteristic lesions in a potassium hydroxide preparation or by observing yellow fluorescence with a Wood's lamp upon examination of the infected body site.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.The microscopic appearance has gained M.furfur the term "the spaghetti and meatballs" fungus.CDC PHIL #2916

Question 8

What is the causative agent of tinea nigra?

Accepted Answer

Tinea nigra,characterized by brown to black nonscale macules that occur most often on the palms of the hands and soles of the feet,is caused by P.werneckii.

Question 9

Identify the following:

Accepted Answer

Fusarium is frequently seen in mycotic dermatitis.In bone marrow transplant patients,mortality from infections caused by the fusaria approaches 100%.Normally,abundant macroconidia with fewer microconidia are produced on a vegetative hyphae.Macroconidia are banana or canoe shaped and are formed singly,in small clusters,or they may cluster together in mats termed sporodochia.CDC PHIL #4010

Question 10

Identify the following:

Accepted Answer

Although these isolates may be recovered from virtually any source,they are primarily implicated in chronic fungal sinusitis.Patients are often misdiagnosed and treated for an extended time for bacterial sinusitis.Microscopic evaluation reveals short conidiophores bearing Conidia in chains that lengthen in an acropetal fashion.Multicelled conidia have angular cross-walls and taper toward the distal end.Alternaria spp.are dematiaceous,rapidly growing fungi with colonies ranging from shades of gray,to brown,to black.CDC PHIL #3963

Question 11

Identify the following:

Accepted Answer

Histoplasmosis is acquired by the inhalation of the microconidia of Histoplasma capsulatum var.capsulatum.Histoplasmosis is also known as reticuloendothelial cytomycosis,cave disease,spelunker's disease,and Darling's disease.H.capsulatum grows as a white to brownish mold.Early growth of the mycelial culture produces round to pyriform microconidia measuring 2 to 5 mm.As the colony matures,large echinulate or tuberculate macroconidia,a characteristic of the species,are formed.
CDC PHIL #10958

Question 12

What is the causative agent of black piedra?

Accepted Answer

P.hortae is the causative agent of black piedra,an infection that occurs on the hairs of the scalp.

Question 13

Identify the following:

Accepted Answer

Direct examination of tissue may reveal S.schenckii as small,cigar-shaped yeast.Although the organism may occasionally be seen in a Gram-stained smear,wet mounts of material are often unrewarding because of the small numbers of organisms present.Microscopic examination from culture reveals thin,delicate hyphae bearing conidia developing in a rosette pattern at the end of delicate conidiophores.Dark-walled conidia are also produced along the sides of the hyphae.CDC PHIL #10603

Question 14

Identify the following:

Accepted Answer

Younger cultures are primarily composed of budding blastoconidia,whereas the older mycelial portion of the colony shows hyphae with blastoconidia in clusters.Annelloconidia are seen in older hyphal colonies.CDC PHIL #3066

Question 15

Identify the following:

Accepted Answer

Aspergillus spp.are the second most isolated fungus after Candida spp.Aspergillus fumigatus is the species most commonly isolated; other pathogenic species include A.flavus,A terreus,and A.niger.Aspergillus may be either uniseriate or biseriate.Uniseriate species are those whose phialides attach directly to the vesicle at the end of the conidiophore.Biseriate species possess a supporting structure called a metula.Metulae are attached directly to the vesicle,and then attached to each metula is a phialide.Chains of conidia can be aligned in very straight,parallel columns or in a radiating pattern around the vesicle,and the conidia can be rough or smooth.CDC PHIL #300

Question 16

Identify the following:

Accepted Answer

Trichosporon spp.produce both arthroconidia and blastoconidia.CDC PHIL #3936

Question 17

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

Accepted Answer

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 18

Identify the following:

Accepted Answer

Macroconidia are spindle shaped with echinulate,thick walls; measuring 12 to 25 mm by 35 to 100 mm and have 3 to 15 cells.The tapering,sometimes elongated,spiny distal ends of macroconidia are key features that distinguish this species.Microconidia are abundantly formed by most isolates,and these may be the only conidia present in cultures that have been serially transferred.CDC PHIL #3209

Question 19

Identify the following:

Accepted Answer

An infrequent cause of disease,Cladosporium is primarily recovered as a laboratory contaminant.Infections are typically confined to the sinuses or following traumatic inoculation.Cladosporium forms brown,to olive,to black hyphae and conidia.Conidiophores are erect and may branch into several conidiogenous cells.Spherical to ovid conidia form blastically on the end of each previously formed conidium.Branched conidium-bearing cells may dislodge,and the three scars of each of these cells give them the appearance of a shield.CDC PHIL #3214

Question 20

Identify the following:

Accepted Answer

Cryptococcus spp.are important causes of meningitis and pulmonary disease.C.neoformans,the most notable pathogen in this group,has become one of the major causes of opportunistic infection in AIDS patients.The organism is commonly found in soil contaminated with pigeon droppings and is most likely acquired by inhalation.Cryptococcus spp.are surrounded by a capsule that produces the characteristic mucoid colonial appearance.Cryptococcus spp.are noted for producing blastoconidia only,without producing true hyphae or pseudohyphae on cornmeal agar.CDC PHIL #4037

Quiz 27: Medically Significant Fungi

Identify the following:

Identify the following:

Identify the following:

Identify the following:

All of the following are examples of dimorphic fungi EXCEPT:

Identify the following:

Identify the following:

What is the causative agent of tinea nigra?

Identify the following:

Identify the following:

Identify the following:

What is the causative agent of black piedra?

Identify the following:

Identify the following:

Identify the following:

Identify the following:

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

Identify the following:

Identify the following:

Identify the following: