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MYCOLOGY AND VIROLOGY > Diagnostic Mycology PART 1 > Flashcards

Diagnostic Mycology PART 1 Flashcards

1
Q

Characteristic Features of Fungi Seen in Direct Examination of Clinical Specimens: Morphologic Form Found in Specimens

A
  1. Yeastlike
  2. Spherules
  3. Yeast and pseudohyphae or hyphae
  4. Pauciseptate hyphae
  5. Hyaline septate hyphae
  6. Dematiaceous septate hyphae
  7. Sclerotic bodies
  8. Granules
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2
Q

Yeastlike fungi:

A

1.Histoplasma capsulatum (2-5)
2.Sporothrix spp. (2-6)
3.Cryptococcus spp. (2-15)
4.Malassezia furfur (infungemia) (1.5-4.5 )
5.Blastomyces spp. (8-15)
6.Paracoccidioides brasiliensis (5-60)

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3
Q

Small; oval to round budding cells;
often found CLUSTERED IN HISTIOCYTES;
difficult to detect when present in small
numbers

A

Histoplasma capsulatum

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4
Q

Small; oval to round to CIGAR SHAPED
single or multiple buds present;
uncommonly seen in clinical specimens

A

Sporothrix spp.

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5
Q

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

A

Cryptococcus spp.

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6
Q

Small; BOTTLE SHAPED cells, buds separated
from parent cell by a septum;
emerge from a small collar.

A

Malassezia furfur (in fungemia)

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7
Q

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

A

Blastomyces spp.

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8
Q

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

A

Paracoccidioides brasiliensis

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9
Q

Spherules Fungi:

A
  1. Coccidioides spp. 10-100
  2. Rhinosporidium seeberi 6-300 (protozoan pathogen that is studied in
    mycology)
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10
Q

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

A

Coccidioides spp.

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11
Q

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

A

Rhinosporidium seeberi

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12
Q

Yeast and pseudohyphae or hyphae fungi:

A
  1. Candida spp. except Candida glabrata 5-10
  2. M. furfur (in tinea versicolor) 3-8 (yeast)
    2.5-4 (hyphae)
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13
Q

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.

A

Candida spp. except Candida glabrata

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14
Q

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

A

M. furfur (in tinea versicolor)

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15
Q

Pauciseptate hyphae Fungi:

A

Mucorales: Mucor,Rhizopus, and other
genera 10-30

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16
Q

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

A

Mucorales: Mucor, Rhizopus, and other
genera

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17
Q

Hyaline septate hyphae Fungi:

A
  1. Dermatophytes, skin and nails 3-15
  2. Dermatophytes, hair 3-15
  3. Aspergillus spp 3-12
  4. Geotrichum spp. 4-12
  5. Trichosporon spp. 1-4 by 8
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18
Q

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

A

Dermatophytes, skin and nails

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19
Q

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

A

Dermatophytes, hair

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20
Q

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

A

Aspergillus spp.

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21
Q

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

A

Geotrichum spp.

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22
Q

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

A

Trichosporon spp.

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23
Q

Dematiaceous septate hyphae fungi:

A

1.Bipolaris spp.,
2.Cladosporium spp.,
3.Curvularia spp.,
4.Exophiala spp.,
5.Exserohilum spp.,
6.Hortaea werneckii,
7.Phialophora spp

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24
Q

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

A

BEECCH Phia 2-6

1.Bipolaris spp.,
2.Cladosporium spp.,
3.Curvularia spp.,
4.Exophiala spp.,
5.Exserohilum spp.,
6.Hortaea werneckii,
7.Phialophora spp

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25
Q

Sclerotic bodies Fungi:

A

1.Cladosporium carrionii
2.Fonsecaea compacta
3.Fonsecaea pedrosoi
4.Phialophora verrucosa
5.Rhinocladiella aquaspersa

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26
Q

White, soft granules without a
cementlike matrix. 200-300

A

Acremonium
2.Acremonium falciforme
3.Acremonium kiliense
4.Acremonium recifei

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27
Q

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

A

sclerotic bodies
(5-20)
1.Cladosporium carrionii
2.Fonsecaea compacta
3.Fonsecaea pedrosoi
4.Phialophora verrucosa
5.Rhinocladiella aquaspersa

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28
Q

Black, hard grains with a cementlike
matrix at the periphery

A

Aspergillus 500-1000
-Aspergillus nidulans

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29
Q

White, soft granule without a cementlike
matrix. 65-160 dm/mm

A

Curvularia
-Curvularia geniculata
-Curvularia lunata

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30
Q

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

A

Exophiala 200-300
-Exophiala jeanselmei

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31
Q

White, soft granules without a
cementlike matrix 200-500

A

Fusarium
-Fusarium moniliforme

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32
Q

300-600 size range granule

A

Fusarium solani

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33
Q

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

A

Madurella 350-500
-Madurella grisea

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34
Q

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.

A

Madurella mycetomatis 200-900

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35
Q

White, soft granules with cementlike
matrix at the periphery. 300-600

A

Neotestudina
-Neotestudina rosatii

36
Q

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

A

Pseudallescheria 200-300
-Pseudallescheria boydii

37
Q

fungal infections that involve hair, skin, or nails without direct invasion of deeper tissue

A

Superficial (cutaneous) mycoses

38
Q

Infections that are confined to the subcutaneous tissue without dissemination to distant sites

A

Subcutaneous mycoses

39
Q

Four categories of mycoses according to the type of infection:

A

Superficial (cutaneous) mycoses
Subcutaneous mycoses
Systemic mycoses
Opportunistic mycoses

40
Q

Affects the skin and hair epidermis

A

Superficial Mycoses

41
Q

Affects the skin and nail

A

Cutaneous Mycoses

42
Q

Affects the subcutaneous tissues

A

subcutaneous mycoses

43
Q

Affects organs

A

Systemic or deep mycoses

44
Q

usually occur in immunocompetent hosts, are not always as virulent, and may lead to
subclinical disease.

A

primary pathogens

45
Q

Infect immunocompromised hosts. Opportunistic pathogens include almost any fungus present in the environment

A

Opportunistic pathogens

46
Q

Virulence factors:

A

1.The organism’s size (with inhalation, the organism must be small enough to reach the alveoli)
2.The organism’s ability to grow at 37°C at a neutral pH
3. Conversion of the dimorphic fungi from the mycelial form into the corresponding yeast or spherule form in the host
4.Toxin production

47
Q

most common specimens collected for fungal culture

A

Respiratory Tract Secretions

48
Q

For optimal recovery of fungi, media without antibiotic and a media containing antibacterial antibiotics should be used to prevent
overgrowth of contaminants

A

Respiratory Tract Secretions

49
Q

antifungal agent cycloheximide prevents overgrowth by rapidly growing molds and should be included in at least one of the culture media

A

Respiratory Tract Secretions

50
Q

Specimens may be stored at room temperature if processing is completed
within 2 hours; if processing is delayed, specimens should be refrigerated
at 4°C

A

Respiratory Tract Secretions

51
Q

centrifuged and the concentrated sediment used to inoculate the culture medium; cultures should be examined daily

A

Cerebrospinal Fluid (CSF)

52
Q

< 1 mL spx submitted for culture:

A

Cerebrospinal Fluid (CSF)

53
Q

centrifuged, 1-drop aliquots of the sediment should be placed on several areas on the agar surface

A

Cerebrospinal Fluid (CSF)

54
Q

should be processed promptly. If prompt processing is not possible, samples should be kept at room temperature or placed in a 30°C incubator, specimens should NEVER be refrigerated.

A

Cerebrospinal Fluid (CSF)

55
Q

provide an accurate method for determining the cause in many instances of disseminated fungal infections

A

Blood

56
Q

placed directly onto microscopic slides and
inoculated onto non inhibitory media in either a X- or C-shaped pattern.

A

Corneal scrapings

57
Q

concentrated by centrifugation and the
sediment should be used for smears and culture.

A

Vitreous humor aspiration:

58
Q

Media containing cycloheximide should be avoided to prevent inhibition of potential isolates

A

Eye (Corneal Scrapings or Vitreous Humor)

59
Q

Samples collected from lesions may be obtained by scraping the skin or nails with a scalpel blade or microscope slide; infected hairs are removed by plucking them with forceps.

A

Hair, Skin, and Nail Scrapings

60
Q

Only the _____should be sampled, because the
centers often contain non viable organisms

A

leading edge of skin lesions

61
Q

Hair, Skin, and Nail Scrapings Specimens should be placed in a sterile container; they should not be

A

refrigerated

62
Q

Hair, Skin, and Nail Scrapings Cultures should be incubated

A

minimum of 21 days at 30°C before
being reported as negative.

63
Q

should be transported to the laboratory within 24 hours of collection using culture transport swabs; swabs should be kept moist in sterile
tubes

A

Vaginal

64
Q

Vaginal cultures should be

A

screened for yeasts and incubated at 30°C for 7 days

65
Q

Urine samples collected for fungal culture should be processed as soon after collection as possible; 24-hour urine sample is

A

unacceptable for culture

66
Q

All urine samples should be centrifuged and the sediment cultured using a____to provide adequate isolation of colonies.

A

loop

67
Q

Because urine often is contaminated with gram-negative bacteria, media containing ____ must be used to ensure the recovery of fungi.

A

antibacterial agents

68
Q

If urine processing is completed within 2 hours, samples may remain at room temperature, if processing is delayed,

A

specimens should be refrigerated at 4°C

69
Q

If a urine transport system is used, samples may be stored at room temperature for up to ?

A

72 hours

70
Q

All tissues should be processed before culturing by ___; not grinding is critical

A

mincing

71
Q

Tissue pieces should be pressed into the appropriate culture media so that they are partially embedded, and the cultures should be incubated

A

at 30°C for 21 days (incubation may be extended if clinical suspicion of
a mycotic disease is high)

72
Q

Bone marrow may be collected in a

A

heparinized syringe.

73
Q

Tissue, Bone Marrow, and Sterile Body Fluids
The sample should be placed directly onto the surface of appropriate culture media
and incubated at

A

30°C for 21 days

74
Q

should be concentrated by centrifugation before culturing, and at least 1 mL of specimen should be placed on the surface of appropriate culture media

A

Sterile body fluids

75
Q

TRUE OR FALSE
All specimens should be cultured as soon as possible to ensure the recovery of fungi.

A

TRUE

76
Q

are satisfactory for the recovery of fungi;

A

Agar plates or screw-capped agar tubes

77
Q

preferred, because they provide better aeration of cultures, a large surface area for better isolation of colonies, and greater ease of handling

A

plates

78
Q

TRUE OR FALSE
Dishes should be opened and examined in a certified biological safety cabinet (BSC)

A

TRUE

79
Q

are used, the tube should be as large as possible to provide an adequate surface area for isolation.

A

culture tubes

80
Q

After inoculation, tubes should be placed in a _____for at least ___ to allow the specimen to absorb to the agar surface and
prevent settling at the bottom of the tube.

A

horizontal position
1 to 2 hours

81
Q

Cotton-plugged tubes are unsatisfactory for fungal cultures.

A

TRUE

82
Q

Cultures should be incubated at______ days before they are reported as negative

A

room temperature, or preferably at 30°C,
for 21 to 30 days

83
Q

Addition of 0.5 mg/mL of cycloheximide and 16 mg/mL of chloramphenicol to media has been advocated to inhibit the growth of contaminating molds and bacteria, respectively.

A

TRUE

84
Q

better results have been achieved using a combination of _____as antibacterial agents. Ciprofloxacin at a concentration of 5 mg/mL may be used.

A

5 mg/mL of gentamicin and 16 mg/mL of chloramphenicol

85
Q
A

MYCOLOGY AND VIROLOGY (10 decks)

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