Dermatophytes

Question 1

Dermatophytes are _______ that infect only ___________ epidermal structures including?

Answer 1

molds, keratinized, superficial skin, hair, feathers, horns, hooves, claws, and nails.

Question 2

Infections caused by dermatophytes are called?

Answer 2

ringworm or dermatophytosis.

Question 3

Other yeast and saprophytic fungi cause __________ infections _______ infections caused by dermatophytes; hence the generic term _________ is used to represent all fungal infections of skin.

Answer 3

cutaneous, mimicking, dermatomycosis

Question 4

Dermatophytes: Morphology
* No __________ state (culture): produce _______, ________ hyphae collectively
called _________.
* The asexual reproductive units (______) are found in the _____ mycelium.
* They can develop ________ and _________.

Answer 4

parasitic, septate, branching, mycelium, conidia, aerial, microconidia, macroconidia

Question 5

List the Hyphal characteristics.

Answer 5

spirals, nodules, rackets, chandeliers, and
chlamydioconidia (chlamydiospore)

Question 6

Dermatophytes Parasite state: only ______ and __________ (_______) another asexual
reproductive unit are seen. Sexual spores (_______) are ____ in the parasitic phase.

Answer 6

hyphae, arthroconidias, arthrospores, ascospores, absent

Question 7

What can be seen in the image below?

Answer 7

Question 8

What are the Three important genera of Dermatophytes?

Answer 8

Microsporum, Trichopyton in animals, and Epidermophyton primarily in humans

Question 9

What is the traditional culture medium for identifying Dermatophytes?

Answer 9

Saboroud’s dextrose agar

Question 10

Some dermatophytes in ____ and ____ (but not in ______) produce _______ __________ visible under ultraviolet light (366nm, Wood’s light) (?)

Answer 10

skin, hair, culture, green fluorescence, Microsporum canis

Question 11

What can be seen in the image below?

Answer 11

Some dermatophytes in skin and hair (but not in culture) produce
green fluorescence visible under ultraviolet light (366nm, Wood’s
light) (Microsporum canis)

Question 12

What can be seen in the image below?

Answer 12

Some dermatophytes in skin and hair (but not in culture) produce
green fluorescence visible under ultraviolet light (366nm, Wood’s
light) (Microsporum canis)

Question 13

What can be seen in the image below?

Answer 13

Some dermatophytes in skin and hair (but not in culture) produce
green fluorescence visible under ultraviolet light (366nm, Wood’s
light) (Microsporum canis)

Question 14

Question 15

How are Dermatophytes transmitted?

Answer 15

• Transmission: Direct and indirect

Question 16

Dermatophytes Pathogenesis:

Answer 16

Proteolytic enzymes (elastase, collagenase, keratinase). Inflammation
with high iron influx, iron is available for fungi growth.

Question 17

Infectious unit (________) –> defect in ________ ______ –> ?
development –> hyphae develops into _________ –> growth pattern in ________ skin –> hair invasion (________) –> germination with ____ formation –> ______ strands growth ____ the hair.

Answer 17

Conidium, stratum corneum , germ tube, hyphae branch, arthroconidia, hairless, ringworm, spore, hyphal, along

Question 18

Accumulation of arthroconidia outside the hair shaft = ?
Accumulation of arthroconidia inside the hair shaft = ?

Answer 18

ectothrix, endothrix

Question 19

Question 20

Question 21

Ringworm normally regress __________, unless ________ bacterial infection(s) is present.

Answer 21

spontaneously, secondary

Question 22

________ animals are more susceptible to dermatophyte infection. Crowding of animals increased ________. Dermatophytes are ________ distributed.

Answer 22

Young, prevalence, globally

Question 23

___________ IR has limited role in protection, ________ IR is decisive in protection and recovery. _______-mediated and _______-mediated hypersensitivity may occur. ____________ __.________ vaccine is used in Europe in cattle.

Answer 23

Humoral, cellular, Antibody, cellular, Mycelial T. verrucosum

Question 24

Dermatophytes: Laboratory diagnosis
- M. ______ and M. _______ may emit fluorescence (Wood’s lamp)

Answer 24

canis, audouini

Question 25

What samples would you collect if trying to diagnose a patient with Dermatophytes? What would you do with those samples?

Answer 25

• Skin scrapings and hair samples for hyphae and arthroconidia observation + 10-20% KOH

Question 26

What stain would you use to ID dermatophytes?

Answer 26

Stain: lactophenol cotton blue

Question 27

What culture would you use to ID dermatophyte infection? At what temperature and for what period of time?

Answer 27

• Culture: Sabouraud’s dextrose agar, 25°C, up to 4 weeks

Question 28

if conducting PCR, what gene would you look for?

Answer 28

• PCR: chitin synthase 1 gene

Question 29

How would you treat a dermatophyte infection? Control?

Answer 29

• Treatment: topical and systemic; miconazole, econozole,
  ketoconazole, itraconazole, and thiobendazole.
  Betadine, chlorhexidine (lotions, ointments)
• Control: disinfection of utensils, equipment and facilities. Screening animals with Wood’s lamp

Question 30

Microsporum canis is generally regarded as a _________ dermatophyte, but it often attacks humans. Most human infections
are acquired from ______. It is the etiologic agent of roughly ____% of the cases of feline ringworm and about ____% of the
cases of canine ringworm in North America; in cats, the infection is most often _________, whereas in dogs, the disease is
more ______. The _____ is the most common site of infection, with areas of ______ around the nose, eyes, and ears, but
the infection can become _______. In addition to humans, cats, and dogs, numerous animals can serve as hosts (?) Microsporum canis produces a _____-_________ fluorescence in _____, and it is associated with small _______ spores. Its colonies are _____ to ____ in color with a characteristic ____, to ______-____ reverse

Answer 30

zoophilic, animals, 98, 70, subclinical, obvious, head, alopecia, generalized, bats,
canaries, cattle, chimpanzees, chinchilla, donkeys, foxes, gibbons, goats, gorillas, guinea pigs, horses, jaguars, lions, lynx,
monkeys, orangutans, pigs, rabbits, sheep, tigers, and others., yellow, greenish, hair, ectothrix, white, buff, yellow, orange-brown

Question 31

What condition is this person suffering from? Explain the causative agent. What can be seen in the slides on the left and in the middle?

Answer 31

Ringworm infection cuased by Microsporum canis.
Microsporum canis produces a yellow-greenish fluorescence in hair, and it is associated with small ectothrix spores. Its colonies are white to buff in color with a characteristic yellow to
orange-brown reverse.

Question 32

Question 33

Microsporum gypseum. This is a __________ dermatophyte that often attacks ____ and ______. It has been isolated from these species (?). _________ _______ spores are typical but ____ in number, and
fluorescence is _____ or ____. The colonies grow ____, producing a _____, ______, ____ to _______
brown surface with a pale ______ to ___ reverse.

Answer 33

geophilic, humans, animals, baboons, buffaloes, cats, cattle, chickens, chimpanzees, chinchillas, dogs, fowl,
guinea pigs, horses, leopards, monkeys, mice, parrots, rabbits, rats, squirrels, tapirs, tigers, and other species (7)

large, ectothrix, few, dull, absent, fast, flat, powdery, buff, cinnamon, yellow, tan

Question 34

What condition is this animal suffering from? Explain the causative agent. What can be seen in the slides on the right and in the middle?

Answer 34

Ringworm caused by Microsporum gypseum.
The colonies grow fast, producing a flat, powdery, buff to cinnamon
brown surface with a pale yellow to tan reverse.

Question 35

What microbe can be seen here?

Answer 35

Question 36

What microbe can be seen here?

Answer 36

Question 37

What microbe can be seen here?

Answer 37

Question 38

What microbe can be seen here?

Answer 38

Question 39

Trichophyton erinacei is a _______ dermatophyte primarily associated
with ringworm in _______, but occasionally it has been isolated from ____ and ____, ____, and ______. Hair invasion is normally ______. The perfect state has ___ been reported. Colonies can be described as?

Answer 39

zoophilic, hedgehogs, mice, rats, dogs, humans, ectothrix, not, flat, powdery, white to ivory white, with a clear yellow diffusing pigment
underneath

Question 40

What condition this patient suffering from? What microbe causes this condition?

Answer 40

Ringworm caused by Trichophyton erinacei.

Question 41

What microbe causes this ?

Answer 41

Trichophyton erinacei.
Colonies are flat,
powdery, white to ivory white, with a clear yellow diffusing pigment
underneath

Question 42

What can be seen in the image below?

Answer 42

Question 43

Trichophyton equinum is a ________ species that
rarely attacks ______; it causes ringworm in _____ and ______, and occasionally, in ____. _____ and _____ are most susceptible, at first
developing swellings that can be felt through the ____. These can progress to small
________ ______ with an ____, a condition often
known as ______ ____. ______ develops as the
lesions enlarge and turn chronic; _____ may fall off
from healed lesions, leaving _____ areas with a ____ eaten appearance.
Hair invasion is by large ______ spores; there is
no _________, and the perfect state has ____
been reported. Colonies are described as?

Answer 43

zoophilic, humans, horses, donkeys, dogs, Foals, yearlings, hair, inflamed ulcers, exudate, girth itch, Alopecia, crusts, bald, moth, ectothrix, fluorescence, not

white to cream- colored with a bright yellow to dark pink or brown reverse

Question 44

What condition is this animal suffering from? What is the causative agent?

Answer 44

Ringworm, Trichophyton equinum

Question 45

What microbe causes this ?

Answer 45

Trichophyton equinum

Question 46

Presently, T. verrucosum
is regarded as the primary cause of ringworm in _____.This _____ dermatophyte often attacks _____; it has been isolated
from (?).
Trichophyton verrucosum produces very _______ ______ spores in ____. Infected hair in humans is not _______, but some florescence
has been noted in ___. Colonies are ____ growing, _______, deeply ______, and _____ to _____. Unlike other dermatophytes, the organisms grows best at ____°C .

Answer 46

cattle, zoophilic, humans, buffalo, canaries, cats, cattle, dogs, donkeys, dromedaries,
fowl, goats, horses, mules, pigs, sheep, and zebu.

large ectothrix, chains, fluorescent, cattle, slow, heaped, folded, white, yellow, 37

Question 47

What condition is this animal suffering from? What is the causative agent?

Answer 47

Ringworm, T. verrucosum

Question 48

What microbe causes this ?

Answer 48

T. verrucosum
Colonies are slow growing, heaped, deeply folded, and white to yellow.

Question 49

What microbe can be seen here?

Answer 49

T. verrucosum

Question 50

Epidermophyton floccosum is the only ______ accepted species in this genus. E. floccosum infects only ____ and _____, and it is virtually confined to _____. Reports of infections in domestic animals are essentially ______, but there are some of isolations from ____ and from a ____. Since ____ is not attacked, there is no ______ under Wood’s lamp. Colonies are usually ?

Answer 50

widely, skin, nails, humans, nonexistent, mice, dog, hair, fluorescence, greenish yellow, olive, or khaki, powdery, with radial furrows and a yellow to tan reverse

Question 51

What condition is this animal suffering from? What is the causative agent?

Answer 51

Tinea pedis
Epidermophyton floccosum

Question 52

What can be seen here?

Answer 52

Macroconidia

Question 53

What can be seen here?

Answer 53

Epidermophyton floccosum
Colonies are usually greenish yellow, olive, or khaki, powdery, with radial furrows and a yellow to tan reverse.

Question 54

What can be seen here?

Answer 54

Chlamydioconidia