IB. Medical mycology | 24. Dermatomycosis (causative agents and diseases).

Question 1

I. Basics
1. What are the major mycoses types of dermatomycosis?

Answer 1

• Superficial mycoses
• Cutaneous mycoses
• Subcutaneous mycoses

Question 2

I. Basics
2. Give a simple definition of Superficial mycoses?

Answer 2

infections limited to the outermost layers of the skin and hair

Question 3

I. Basics
3. Give a simple definition of Cutaneous mycoses?

Answer 3

infections involving the dermis, subcutaneous tissues, muscle and fascia

Question 4

I. Basics
4. Give a simple definition of Subcutaneous mycoses?

Answer 4

infections that extend deeper into the epidermis, as well as invasive hair and nail diseases

Question 5

I. Basics
4. What are Clinical manifestations suggestive of fungal infection?

Answer 5

1. flu-type infection: that has lasted longer than a viral flu
2. chronic respiratory problem: with weight loss and night sweats
3. fever of unknown origin: that does not respond to antibacterial agents
4. any infection with negative bacterial cultures: that does not respond to antibiotics and that does not appear viral
5. signs of meningitis
6. exposure to dust with bird or bat guano

Question 6

I. Basics
5. What are Predisposal factors of fungal infections?

Answer 6

1. diseases causing immunosupression: tumours, AIDS, steroid therapy, diabetes mellitus
2. trauma: burnt wounds - moulds, stabbed injuries - subcutaneous mycosis
3. iatrogenic mycosis: during the immunosupression therapy: irradiation, corticosteroid therapy, administration of broad spectrum antibiotics, cytostatic therapy
4. Nosocomial infections: fungi associated to plastic surfaces (catheters)
5. „voluntarily risks”: alcoholism, drug abusers, microbiologists, mycologists

Question 7

I. Superficial mycoses
1. What are the main features of Superficial mycoses?

Answer 7

1. affect the outermost layer of skin and hair
2. generally do not induce a cellular response to the infection
3. Superficial cosmetic fungal infections of the skin or hair shaft
4. No living tissue is invaded
5. No pathological changes
6. Patient unaware of infection

Question 8

I. Superficial mycoses
2. What is the main source of Superficial mycoses?

Answer 8

Malassezia species → (Pityriasis versicolor)
- Flaky, discolored patches on chest and back

Question 9

I. Superficial mycoses
3. What are the features of Malassezia furfur?

Answer 9

1. Yeast
2. spreading: direct contact, contaminated clothes
3. rarely may cause an opportunistic fungaemia
4. Malassezia folliculitis – after sun exposure
5. is a chronic mild superficial disease of the stratum corneum epidermidis
6. light-skinned patients: lesions initially pink then pale brown
7. dark-skinned patients: skin loses colour, becomes depigmented
8. Occures on trunk, neck, head

Question 10

I. Superficial mycoses
4. How does Malassezia furfur spread?

Answer 10

spreading: direct contact, contaminated clothes

Question 11

I. Superficial mycoses
5. What are the symptoms by Malassezia furfur in light-skinned and dark-skinned patients?

Answer 11

• Light-skinned patients: lesions initially pink then pale brown
• dark-skinned patients: skin loses colour, becomes depigmented

Question 12

I. Superficial mycoses
6. Where does superficial mycoses caused by Malassezia furfur occur?

Answer 12

ccures on trunk, neck, haed

Question 13

I. Superficial mycoses
7. How do we diagnose Superficial mycoses?

Answer 13

• direct microscopic examination of scrapings of infected skin treated with 10-20% KOH
• „spaghetii and meat balls”

Question 14

I. Superficial mycoses
8. How do we treat Superficial mycoses?

Answer 14

• selenium sulfide shampoo
• Ketoconazole, fluconazole – 1-2 weeks

Question 15

II. Subcutaneous mycosis
1. What are the main features of Subcutaneous mycosis?

Answer 15

1. They are present in soil or on vegetation
2. traumatic inoculation by contaminated material
3. in rare cases they become systemic and produce life-threatening disease

Question 16

II. Subcutaneous mycosis
2. Give an example of Subcutaneous mycosis?

Answer 16

Sporotrichosis – typical lymphatic spread with ulceration

Question 17

II. Subcutaneous mycosis
3. What are the treatments for Subcutaneous mycosis?

Answer 17

• local treatment: potassium iodide
• itraconazole
• fluconazole
• amphotericin B

Question 18

III. Cutaneous mycoses
1. What are the features of Cutaneous mycoses?

Answer 18

1. infect only the superficial keratinized tissue (skin, hair, nails)
2. most are unable to grow at 37°C or in the presence of serum
3. 25°C on Sabouraud’s dextrose agar for 2 weeks
4. infections begin in the skin after trauma and contact
5. are classified as: geophilic, zoophilic, anthropophilic depending on their usual habitat

Question 19

III. Cutaneous mycoses
2. Give the classification of cutaneous mycoses?

Answer 19

geophilic, zoophilic, anthropophilic depending on their usual habitat

Question 20

III. Cutaneous mycoses
3A. What are the 2 main Cutaneous mycoses?

Answer 20

1. Dermatophytosis
2. Candidiasis

Question 21

III. Cutaneous mycoses
3B. What are the causative organisms of Dermatophytosis?

Answer 21

• Microsporum
• Trichophyton
• Epidermophyton

Question 22

III. Cutaneous mycoses
3C. What are the causative organisms of Candidiasis?

Answer 22

ausative organisms: Candida albicans, C. tropicalis, C. krusei, ….

Question 23

III. Cutaneous mycoses
4A. How does Cutaneous mycoses begin?

Answer 23

infections begin in the skin after trauma and contact

Question 24

III. Cutaneous mycoses
5. What are the risk factors for Cutaneous mycoses?

Answer 24

moisture, warmth, specific skin chemistry, composition of sebum, prespiration, youth heavy exposure, genetic predisposition

Question 25

III. Cutaneous mycoses 6. What is trichophytin?

Answer 25

a crude antigen preparation that can be used to detect immediate or delayed type hypersensitivity to dermatophytic antigens - Trichophyton is a genus of fungi, which includes the parasitic varieties that cause tinea, including athlete's foot, ringworm, jock itch, and similar infections of the nail, beard, skin and scalp. Trichophyton fungi are molds characterized by the development of both smooth-walled macro- and microconidia.

Question 26

III. Cutaneous mycoses 7. What are the features of Geophilic, zoophilic and antropophilic?

Answer 26

1. Geophilic fungus: Inhabit soil where they decompose keratinaceous debris, dead animals 2. Zoophilic: Parasitic in animals 3. Antropophilic: Parasitic to man

Question 27

III. Cutaneous mycoses - Tinea Pedis (Athlete's Foot) 8A. What is Tinea Pedis (Athlete's Foot)?

Answer 27

1. Tinea pedis is the most prevalent of all dermatophytoses 2. a chronic infection of the toe webs 3. Hyperkeratosis of the sole. 4. There is itching between the toes and the development of small vesicles that rupture and discharge a thin fluid 5. the skin of the toe webs becomes macerated and peels (Trichophyton rubrum, Epidermophyton floccosum)

Question 28

III. Cutaneous mycoses - Tinea Pedis (Athlete's Foot) 8B. What are the varieties of Tinea Pedis (Athlete's Foot)?

Answer 28

other varieties are: the vesicular, ulcerative, and moccasin types, with hyperkeratosis of the sole. (Trichophyton rubrum, Epidermophyton floccosum)

Question 29

III. Cutaneous mycoses - Tinea Pedis (Athlete's Foot) 8C. What is the chronic form of Tinea Pedis (Athlete's Foot)?

Answer 29

peeling and cracking of the skin are the principal manifestations, accompanied by pain and pruritus

Question 30

III. Cutaneous mycoses 9. What is tinea capitis?

Answer 30

1. Microsporum sp. 2. tinea capitis is dermatophytosis of the scalp and hair 3. infection of the hair takes place just above the hair root 4. the infection produces dull gray, circular patches of alopecia, scaling, and itching 5. in prepubescent children, epidemic tinea capitis is usually self limiting

Question 31

III. Cutaneous mycoses 10. What is tinea barbae?

Answer 31

involves the bearded region - cattle (Trichophyton rubrum, T. mentagrophytes)

Question 32

III. Cutaneous mycoses 11. What is favus?

Answer 32

an acute inflammatory infection of the hair follicle caused by T. schoenleinii

Question 33

III. Cutaneous mycoses 12. What is the treatment for both Tinea capitis (Microsporum sp.) and Tinea barbae (Trichophyton rubrum, T. mentagrophytes)?

Answer 33

- Treatment: scalp infections are treated with griseofulvin for 4 - 6 weeks - Shampoos and miconazole cream or other topical antifungal agents may be effective if used for weeks - Ketoconazole, itraconazole and terbinafine

Question 34

I. Superficial mycoses 9. What are the causative agents of Superficial mycoses?

Answer 34

Question 35

II. Subcutaneous mycosis 4. What are the causative agents of Subcutaneous mycosis?

Answer 35

Question 36

I. Superficial mycoses 9. What are the causative agents of Superficial mycoses?

Answer 36

Question 37

III. Cutaneous mycoses 13. What are the causative agents of subcutaneous mycosis?

Answer 37

Question 37

II. Subcutaneous mycosis 4. What are the causative agents of Subcutaneous mycosis?

Answer 37