Cutaneous and Subcutaneous Mycoses PART1

Question 1

Cutaneous Mycoses:

Answer 1

Microsporum
Trichophyton
Epidermophyton

Question 2

Subcutaneous Mycoses

Answer 2

Mycetoma
Chromoblastomycosis
Phaeohyphomycosis
Sporotrichosis

Question 3

-Most common fungal infections of humans. Usually referred to as tinea (Latin for “worm” or “ringworm”)

Answer 3

Cutaneous Mycoses/ TINEA

Question 4

Ringworm of the body

Answer 4

Tinea corporis

Question 5

Ringworm of the groin or “jock itch”

Answer 5

Tinea cruris

Question 6

Ringworm of the scalp and hair

Answer 6

Tinea capitis

Question 7

Ringworm of the beard

Answer 7

Tinea barbae

Question 8

Ringworm of the nail

Answer 8

Tinea unguium

Question 9

-Members of this genus are widely
distributed and are the most
important and common causes of
infections of the feet and nails
- Commonly seen in adult infections
- Most cosmopolitan species are
anthropophilic or “human loving”
- Hairs infected with organisms do not fluorescence under the UV light of a Woods lamp

Answer 9

Trichophyton

Question 10

Calcofluor white/KOH preparations reveal the presence of hyaline septate hyphae or arthroconidia

Answer 10

Trichophyton

Question 11

-Infected hairs may reveal the hair shaft to be filled with masses of large arthroconidia (4-7 um) in chains (endothrix infection). Infected hairs that show external masses of spores that
ensheaths the hair shaft (ectothrix infection)

Answer 11

Trichophyton spp.

Question 12

infected hairs reveal hyphae and air spaces within the shaft

Answer 12

Trichophyton Shoenleinii

Question 13

Trichophyton spp. Initial growth must be subcultured onto _____ to induce sporulation

Answer 13

cornmeal agar or potato dextrose agar

Question 14

are the most common species recovered in the clinical laboratory

Answer 14

T. rubrum and T. mentagrophytes

Question 15

is slow-growing, produces a flat/heaped-up
colony, generally WHITE TO REDDISH, with cottony or velvety surface

Answer 15

Trichophyton rubrum

Question 16

Characteristic cherry-red color best observed on the reverse side of the colony (after 3-4 weeks of incubation)

Answer 16

T. rubrum

Question 17

T. rubrum Two types of colonies may be produced:

Answer 17

fluffy and granular

Question 18

microconidia are uncommon in most of the
fluffy strains and more common in the granular strains. Microconidia occur as small, teardrop-shaped conidia often borne laterally along the sides of the hyphae
- Macroconidia are less common; they appear in granular strains as thin-walled, smooth-walled, multi celled, cigar-shaped conidia with three to eight septa
- has no specific nutritional requirements
- Does not perforate hair in vitro or produce
urease

Answer 18

T. rubrum

Question 19

produce two distinct colonial forms:
downy variety recovered from patients with tinea pedis and the granular variety recovered from lesions acquired by contact with animals

Answer 19

T. mentagrophytes

Question 20

• Rapidly growing colonies
• Appear white to cream-colored or yellow
• Cottony or downy
• Coarsely granular to powdery
• May produce a few spherical microconidia
• Reverse side of colony is usually ROSE BROWN, occasionally orange to deep red (may be confused for T. rubrum)

Answer 20

T. mentagrophytes

Question 21

-colonies sporulate freely;
- microconidia in grapelike clusters and thin-walled, smooth walled, cigar-shaped macroconidia measuring 6 × 20 μm to 8 × 50 μm, with two to five septa
- Macroconidia characteristically exhibit a definite narrow attachment to their base.
- Spiral hyphae may be found in one third of the isolates recovered.

Answer 21

T. mentagrophytes

Question 22

• produce urease within 2 to 3 days after
  inoculation onto Christensen’s urea agar
• Perforate hair unlike T. rubrum

Answer 22

T. mentagrophytes

Question 23

Responsible for an epidemic form of tinea capitis that commonly occurs in children

Answer 23

T. tonsurans

Question 24

causes a low-grade superficial lesion of varying
severity and produces circular, scaly patches of
alopecia (loss of hair)

Answer 24

T. tonsurans

Question 25

The stubs of hair remain in the epidermis of the scalp after the brittle hairs have broken off, which may give the typical “black dot” ringworm appearance

Answer 25

T. tonsurans

Question 26

-Cultures of develop slowly and are typically buff to brown, wrinkled, and suedelike in appearance. - colony surface shows radial folds and often develops a craterlike depression in the center with deep fissures

Answer 26

T. tonsurans

Question 27

Reverse side of the colony is YELLOWISH TO REDDISH BROWN. Numerous microconidia with flat bases are produced on the sides of hyphae.

Answer 27

T. tonsurans

Question 28

- With age, the microconidia tend to become pleomorphic, are swollen to elongated, and are referred to as balloon forms

Answer 28

T. tonsurans

Question 29

-T. tonsurans growth is greatly enhanced by the presence of ____in casein agar

Answer 29

thiamine or inositol

Question 30

Colonies are small, heaped, and folded; occasionally they are flat and disk-shaped.

Answer 30

T. verrucosum

Question 31

At first, they are glabrous and waxy, with a short aerial mycelium. Colonies range from GRAY TO WAXLIKE TO BRIGHT YELLOW, The reverse of the colony most often is nonpigmented but may be yellow

Answer 31

T. verrucosum

Question 32

causes a severe type of infection called favus; characterized by the formation of yellowish cup-shaped crusts, or scutulae on the scalp

Answer 32

T. schoenleinii

Question 33

A distinctive invasion of the infected hair, the favic type, is demonstrated by the presence of large, inverted cones of hyphae and arthroconidia at the base of the hair follicle and branching hyphaethroughout the length of the hair shaft

Answer 33

T. schoenleinii

Question 34

Slow grower (30 days or longer) - produces a WHITE TO LIGHT GRAY colony with a waxy surface

Answer 34

T. schoenleinii

Question 35

-Colonies have an irregular border consisting mostly of submerged hyphae, which tend to crack the agar. - The surface of the colony is usually nonpigmented or tan, furrowed, and irregularly folded

Answer 35

T. schoenleinii

Question 36

The reverse side of the colony is usually tan or nonpigmented.

Answer 36

T. schoenleinii

Question 37

The hyphae tend to become knobby and club-shaped at the terminal ends, with the production of many short lateral and terminal branches

Answer 37

T. schoenleinii

Question 38

All strains may be grown in a vitamin-free medium and grow equally well at room temperature or at 35°C to 37°C.

Answer 38

T. schoenleinii

Question 39

- Very slow growing - Beginning as cone-shaped, cream-colored, glabrous colonies

Answer 39

T. violaceum

Question 40

-Later these become heaped up, verrucous (warty), violet to purple, and waxy in consistency. - Colonies may often be described as “port wine” in color. - The reverse side of the colony is purple or nonpigmented.

Answer 40

T. violaceum

Question 41

- microconidia and macroconidia generally are not present; only sterile, distorted hyphae and chlamydoconidia are found

Answer 41

T. violaceum

Question 42

- Growth of T. violaceum is enhanced on media containing

Answer 42

thiamine

Question 43

-Early detection medium (Kane and Smitka) = 4% casein and 0.5% yeast extract - organism is recognized by its early hydrolysis of casein and very slow growth rate

Answer 43

T. verrucosum

Question 44

Very slow growing

Answer 44

T. violaceum

Question 45

Slow grower (30 days or longer)

Answer 45

T. schoenleinii

Question 46

Slow grower (14-30 days)

Answer 46

T. verrucosum