Fungal skin infections checkpoints

Question 1

I. What enzyme do all the dermatophytes secrete?

Answer 1

I. keratinase

Question 2

II. What are some of the common species of dermatophytes that cause tinea infections? And visually

Answer 2

I. Trichophyton- a few smooth-walled cylindrical, club-shaped, cigar-shaped macro, prominent micro, coiled or spiral-shaped hyphae
II. microsporum- rough-walled, spindle shaped macro, prominent micro (infects hair and skin)
III. epidermophyton- macroconidia- smoothwalled “clubshaped”, no micro

Question 3

III. Do species of Microsporum typically infect the nails?

Answer 3

I. Only hair and skin

Question 4

IV. Describe the appearance of tinea corporis (ringworm).

Answer 4

I. It looks like a parasitic worm

Question 5

V. Pityriasis versicolor is cause by which genus of fungi? How do they appear upon staining?

Answer 5

I. Malassezia globose

II. KOH staining reveals meatballs and spaghetti appearance

Question 6

VI. Which dermatophyte species can be ID by using a Wood’s lamp?

Answer 6

I. M. Canis

Question 7

VII. Which form(s) does Candida take during invasive diseases when isolated from host tissue?

Answer 7

I. Mold form

Question 8

VIII. Where are the chlamydospores commonly found on Candida?

Answer 8

I. At the terminal end

Question 9

IX. When grown in serum at 37°C, what structure grows from the yeast form of Candida and can be used in diagnosis?

Answer 9

I. Yeast cells begin to form a hyphae called a germ tube

Question 10

X. Which areas of the body does Candida spp. commonly colonize?

Answer 10

I. Mouth, skin and nails, GU, GI, disseminated

Question 11

XI. What are some of the major risk factors that contribute to invasive candidiasis?

Answer 11

I. DM, immunocompromised pt.