Mycology review

A patients sputum specimen contains a dimorphic fungus. If the sputum is put on a slide and a coverslip added, what would you expect to observe?

a. Aseptate hyphae

b. Septate hyphae

c. Aerial hyphae

d. Yeasts

d. Yeasts

Penicillium produce what type of conidia?

a. Annelloconidia

b. Phialoconidia

c. Blastoconidia

d. Poroconidia

b. phialoconidia

Bipolaris produce what type of conidia?

a. Annelloconidia

b. Phialoconidia

c. Blastoconidia

d. Poroconidia

d. poroconidia

Microconidium are

a. Septate

b. Aseptate

c. Pseudohyphae

d. Microaleuriospores

d. microaleuriospores

c. pseudohyphae

Blastoconidia that have elongated are termed:

a. Chlamydospores

b. Mother cells

c. Pseudohyphae

d. True hyphae

A patient is seen by his physician for a hard, nonmoving nodule below the skin on his right index finger. There are no other symptoms. Circle the letter of the correct answer. The infection that this patient is most likely presenting is:

a. Superficial

b. Cutaneous

c. Subcutaneous

d. Systemic

c. subcutaneous

d. aseptate

a. sporangiospores

e. zygospores

The taxonomic phylum Zygomycota is distinct in that the hyphae are usually

______________ . The typical asexual reproductive structures are ______________ , and the sexual stage is characterized by the formation of

______________ .

a) Sporangiospores

b) Arthroconidia

c) Ascospores

d) Aseptate

e) Zygospores

f) Basidiospores

g) Septate

left: Ascus

right top: Cleistothecium

Right bottom: Ascospores

1.    The fungal organism most acommonly found in vaginal infections is:

a.    Geotrichum candidum

b.    Coccidioides immitis

c.    Candida albicans

d.    Cryptococcus neoformans

C. candida albicans

1.    Which is the most useful mounting fluid for nail scrapings?

a.    Saline

b.    Potassium hydroxide

c.    Acetic acid

d.    Lactophenol cotton blue

B. Potassium Hydroxide

1.    List 3 general rules for good collection of fungal specimens.

a.     

b.     

c.     

a. spec. collected rom correct site

b. sterile collection technique

c. adequate specimen delivered promptly and adequately labeled

Two fungi that may be found in CSF are _______ and________.

crypto. neoformans and candida spp.

T /F   Granules from subcutaneous lesions only represent necrotic material and therefore should be disregarded.

False

  T/F   Fungal growth can be easily detected in blood culture bottles because the broth medium quickly becomes cloudy/turbid like bacteria.

False

1.    The best medium to isolate fungal opportunists from a nonsterile site is:

a)    Inhibitory mold agar

b)   Brain Heart infusion agar with blood, gentamicin, chloramphenicol and cycloheximide

c)    BHI agar with blood

d)   Dermatophyte test medium

A inhibitory mold sugar

1.    The best medium to isolate Cryptococcus neoformans in bronchial washings from an AIDS patient is:

a.    Sabouraud brain heart infusion agar

b.    MacConkey agar

c.    Inhibitory mold agar

d.    Birdseed agar

D. birdseed agar

What is considered an intermediate growth rate for fungus?

mature colony in 6-10 days

T/F   Potato dextrose agar promotes sporulation?

True

1.    Canoe/Banana shaped macrophialoconidia with foot cells are diagnostic of:

a.    Paecilomyces spp.

b.    Curvularia spp.

c.    Fusarium spp.

d.    Nigrospora spp

C. Fusarium spp.

  T /F   Dematiaceous organisms exhibit light-colored hyphae and/or conidia.

False

T/F   Aspergillus fumigatus produces phialides and phialoconidia only at the end of the vescicle.

True

  T /F   The cornea of the eye is easily susceptible to infection.

False

T/F   In aspergillosis the etiologic fungus may be isolated only once and still be considered significant.

True

  Otomycosis involves:

a.    Deep inner ear infections

b.    Middle ear infections

c.    External ear infections

d.    A deep understanding of Macro-economics

C. external ear infections

T /F   Acremonium exhibits repeatedly forking conidiophores with terminal balls of conidia.

False

  T/ F   Potato dextrose agar promotes sporulation?

True

Circle the letter(s) of the statement(s) that pertain to the genus Trichophyton.
a. Smooth, thin-walled macroconidia
b. Generally numerous macroconidia
c. Microconidia in grapelike clusters
d. Numerous or few microconidia
e. Rough spindle-shaped macroconidia

a, c, d

T/F Epidermaphyton produces no microconidia

True

T/F, E. floccosum macroconidia may be confused with those of T.
verrucosum

False

Circle all that apply: Test(s) that help differentiate T. mentagrophytes from T.
rubrum.
a. Urease test
b. Trichophyton nutritional agar tests
c. Red pigment on potato destrose agar
d. Polished rice grains test
e. In vitro hair perforation

A, c, e

T/F All dermatophytes infecting humans cause cutaneous mycoses, but not all cutanoueous mycoses are elicited by dermatophytes

True

Hair fluorescence is produced from infection with organisms of
the ________________ genus.

microsporum

T/F Dermatophytes are usually rapid growers.

False

common name for dermatophytosis of the foot or tinea pedis
is ______________________.

athletes foot

his organism is an etiologic agent of epidemic dermatophytosis of the foot in
summer camps and institutions. It does not infect hair.
a. Trichophyton violaceum
b. Epidermophyton floccosum
c. Microsporum audouinii
d. Trichophyton mentagrophytes
e. Trichosporon beigelii

B. epidermophyton floccosum

10. c,d,e,f

11. c

12. D

13. B

14. B

15. D

Choose all that apply: Torulopsis glabrata may be normal flora of:
a. Vagina
b. Throat
c. Stool
d. All of the above
e. B and C

D. all of the above

Ascomycota

sexual reproduction resulting in ascospores

Basidiomycota

sexual reproduction resulting in basidospores

Zogomycota

asexual reproduction resulting in zygospores

Deuteromycota

asexual reproduction resulting in conidia

(includes most pathogenic fungi)

Clinically important fungi

all have an asexual name

(anamorph)

some have a sexual name

(teleomorph)

Conidiogenesis

asexual formation of conidia

Conidiophore

supportive stalk for the conidia

may be conidiogenous or support the conidiogenous cells.

Blastic

type of conidiogenesis where the parent cell enlarges and a septum separates the enlarged portion into a daughter cell.

Thallic

A septum forms first and then the growing point ahead of it becomes the daughter cell.

Arthric

A daughter cell fragments withint the hyphal strand.

Holo

all wall layers of the parent cell are involved in daughter conidium development

Blastoconidia

holoblastic conidia formed by budding along hyphae, pseudophyphae, or a single cell (i.e. yeast)

Poroconidia

holoblastic conidia produced through a pore in the parent cell wall.

Phialoconidia

conidia arising from a phialide, - first is developed holoblastically

- the rest are enteroblastically derived

phialide

vase-shaped cell that may be ringed at the top by a cup-shaped collarette.

Annelloconidia

conidia arising from an annellide

- the first one develops holloblastically

- the subsequent are enteroblastically derived

annellide

a vase-shaped cell that exhibits a new ring of material as each conidium passes through.

Chlamydoconidia

thick-walled hyphal survival conidium formed during poor environmental conditions, which germinate and produce conidia when a better climate occurs

- may be terminal, sessile, or intercalary

Chlamydospore

thick-walled vesicle of C. albicans and some other yeast which neither germinates nor produces conidia when mature.

Arthroconidia

conidia produced by fragmentation of the hyphal strand through separation points

- may form adjacently or separated by disjunctor cells.

Sporangia

- asexual sac-like structures at the tip of support stalk.

- contain sporangiospores

- produced by Zygomycota

Microconidia

- smaller conidia in fungi that produce both large and small conidia

- usually single-celled, round, ovoid, pear shaped, or club shaped

Macroconidia

- larger conidia in fungi that produce both

- may be single celled, but usually multicelled.

Antheridium

male cell

Ascogonium

female cell

Ascus

zygote

Ascospores

formed by nuclear division within the ascus

Ascocarp

protective sac which houses the asci & ascospores

Cleistothecium

completely enclosed ascocarp

Basidium

- club-shaped mother cell from which basidiospores arise

(Filobasidiella neoformans)

(( Cryptococcus neoformans ))

Basidiospores

- sexual spore formed by the fusion of two compatible nuclei and cells into a zygote

Basidiocarp

- protective structure which houses basidia and basidiospores

Zygophore

- arm of hyphae that extends toward another compatible arm to produce a zygospore

Zygospore

- sexual spore formed by fusion of two compatible hyphal arms

Zygosporangium

- thick outer layer covering a zygospore

Mycelia sterilia

no reproductive structures just lots of hyphae

Morphology :

Cottony / Wooly

Very high dense aerial mycelium

Morphology:

Velvety

low aerial mycelium

Morphology:

granular or powdery

dense production of conidia

Morphology:

Glabrous

waxy, smooth, no aerial mycelium

Morphology:

Rugose

Deep furrows irregularly radiating from center

Morphology:

Umbonate

button-like central elevation

Morphology:

Verrucose

wrinkled, convoluted surface

Hyaline

lightly colored conidia and hyphae

Calcofluor white

- binds to chitin

- fluoresces under UV

SAB

Sabourad Dextrose Agar

nonselective media

- acid pH of 5.6

nutritionally poor - limits bacterial growth but allows opportunist and pathogens to grow

BHI with blood

nutritionally richer for specimens with normally sterile body sites

Other nonselective media

Potato dextrose agar

corn meal media

potato flake agar

BHI w/GM & CH

antibiotics inhibit bacteria and Nocardia will not grow

BHI with cycloheximide

additionally inhibits fungal opportunists

DTM

Dermatophyte test media

frequently used in dermatology offices with antibiotics and phenol red

SH Primary Isolation Media

BHI blood agar with chloramphenicol and gentamicin

Potato Dextrose Agar

Secondary Subculture Media

Corn meal with tween 80

Potato Flakes Agar

Incubation Temperatures

25 - acceptable but some organisms multiply slower

30 - general temperature for incubation of fungal cultures

37 - may actually inhibit some fungi

Incubation time

Rapid growers - 5 days or less

Intermediate - 6-10 days

Slow growers - 11-21 days

Lactophenol Cotton Blue

- phenol kills organism

- lactic acid preserves fungal structures

- cotton blue stains chitin

Culture preservation

- distilled water

- freezing

- lyophilization

- oil overlay

Fungal opportunists

saprobic

airborne

abundant sporulation

inhalation

rapid-growing (4-5 days)

poor growth at 35-37

often pigmented

usually nonpathogenic

Fungal pathogens

- generally slow growing

- may require special media

- no wide variety of pigmentation