Characteristic Features of Fungi Seen in Direct Examination of Clinical Specimens:

Question 1

Small; oval to round budding cells; often found clustered in histiocytes; difficult to detect when present in small numbers

Answer 1

Histoplasma capsulatum

Question 2

Small; oval to round to cigar-shaped; single or multiple buds present; uncommonly seen in clinical specimens.

Answer 2

Sporothrix spp.

Question 3

Cells exhibit great variation in size; usually spherical but may be football-shaped; buds single or multiple and “pinched off”; capsule may or may not be evident; occasionally, pseudohyphal forms with or without a capsule may be seen in exudates of cerebrospinal fluid.

Answer 3

Cryptococcus spp.

Question 4

Small; bottle-shaped cells, buds separated from parent cell by a septum; emerge from a small collar.

Answer 4

Malassezia furfur (in fungemia)

Question 5

Cells are usually large, double refractile when present; buds usually single; however, several may remain attached to parent cells; buds connected by a broad base.

Answer 5

Blastomyces spp.

Question 6

Cells are usually large and are surrounded by smaller buds around the periphery (“mariner’s wheel appearance”); smaller cells may be present (2-5 μm) and resemble H. capsulatum; buds have “pinched-off” appearance

Answer 6

Paracoccidioides brasiliensis

Question 7

Spherules vary in size; some may contain endospores, others may be empty; adjacent spherules may resemble Blastomyces spp.; endospores may resemble H. capsulatum but show no evidence of budding; spherules may produce multiple germ tubes if a direct preparation is kept in a moist chamber greater than/equal to 24 hr.

Answer 7

Coccidioides spp.

Question 8

Large, thick-walled sporangia containing sporangiospores are present; mature sporangia are larger than spherules of Coccidioides; hyphae may be found in cavitary lesions.

Answer 8

Rhinosporidium seeberi
(protozoan pathogen that is studied in mycology)

Question 9

Cells usually exhibit single budding; pseudohyphae, when present, are constricted at the ends and remain attached like links of sausage; hyphae, when present, are septate.

Answer 9

Candida spp. except Candida glabrata

Question 10

Short, curved hyphal elements are usually present, along with round yeast cells that retain their spherical shape in compacted clusters; “spaghetti and meatballs.”

Answer 10

M. furfur (in tinea versicolor)

Question 11

Hyphae are large, ribbonlike, often fractured or twisted; occasional septa may be present;
smaller hyphae are confused with those of Aspergillus spp., particularly Aspergillus flavus

Answer 11

Mucorales: Mucor, Rhizopus, and other genera

Question 12

Hyaline, septate hyphae are commonly seen;
chains of arthroconidia may be present.

Answer 12

Dermatophytes, skin and nails

Question 13

Arthroconidia on periphery of hair shaft producing a sheath indicate ectothrix infection; arthroconidia formed by fragmentation of hyphae in the hair shaft indicate endothrix infection.
Long hyphal filaments or channels in the hair shaft indicate favus hair infection.

Answer 13

Dermatophytes, hair

Question 14

Hyphae are septate and exhibit dichotomous, 45-degree branching; larger hyphae, often disturbed, may resemble those of Mucorales.

Answer 14

Aspergillus spp.

Question 15

Hyphae and rectangular arthroconidia are present and sometimes rounded; irregular forms may be present

Answer 15

Geotrichum spp.

Question 16

Hyphae and rectangular arthroconidia are present and sometimes rounded; occasionally, blastoconidia may be present.

Answer 16

Trichosporon spp

Question 17

Dematiaceous polymorphous hyphae are seen; budding cells with single septa and chains of swollen rounded cells are often present; occasionally, aggregates may be present in infection caused by Phialophora and Exophiala spp.

Answer 17

Bipolaris spp., Cladosporium spp., Curvularia spp., Exophiala spp., Exserohilum spp., Hortaea werneckii, Phialophora spp.

Question 18

Brown, round to pleomorphic, thick-walled cells with transverse septations; commonly, cells contain two fission planes that form a tetrad of cells (sclerotic bodies).

Answer 18

Cladosporium carrionii
Fonsecaea compacta
Fonsecaea pedrosoi
Phialophora verrucosa
Rhinocladiella aquaspersa

Question 19

White, soft granules without a cementlike matrix.

Answer 19

Acremonium
-Acremonium falciforme
-Acremonium kiliense
-Acremonium recifei

Question 20

Black, hard grains with a cementlike matrix at the periphery

Answer 20

Aspergillus
-Aspergillus nidulans

Question 21

White, soft granule without a cementlike matrix.

Answer 21

Curvularia
-Curvularia geniculata
-Curvularia lunata

Question 22

Black, soft granules, vacuolated, without a cementlike matrix, made of dark hyphae and swollen cells.

Answer 22

Exophiala
-Exophiala jeanselmei

Question 23

White, soft granules without a cementlike matrix.

Answer 23

Fusarium
-Fusarium moniliforme

Question 24

Black, soft granules without a cementlike matrix; the periphery is composed of polygonal swollen cells and the center has a hyphal network.

Answer 24

Madurella -Madurella grisea

Question 25

Black to brown, hard granules;
two types:
(1) rust-brown, compact, filled with cement-like matrix;
(2) deep brown, filled with numerous vesicles, 6-14 μm in diameter, cementlike matrix in periphery, central area of light-colored hyphae.

Answer 25

Madurella mycetomatis

Question 26

White, soft granules with cementlike matrix at the periphery.

Answer 26

Neotestudina
-Neotestudina rosatii

Question 27

White, soft granules composed of hyphae and swollen cells at the periphery in a cementlike matrix.

Answer 27

Pseudallescheria
-Pseudallescheria boydii

Question 28

Black, soft granules composed of polygonal swollen cells at the periphery; center is network of hyphae; no cementlike matrix

Answer 28

Pyrenochaeta
-Pyrenochaeta romeroi