NAJRAN UNIVERSITY College of Applied Medical Sciences

1. NAJRAN UNIVERSITY College of Applied Medical Sciences Medical Mycology Superficial mycosis By Dr. Ahmed Morad Asaad Associate Professor of Microbiology

2. Clinical classification • The most important classification for clinicians into: • 1- Superficial (cutaneous) mycosis • Infection of keratinized tissues (skin, hair or nail): • Tineaversicolor • Dermatophytosis • 2-Subcutaneous mycosis • Infection of subcutaneous tissues (deep ulcerated skin lesion) and rarely spread to systemically • Chromomycosis • Sporotrichosis • 3- Systemic (deep) mycosis • Infection of viscera involoving different body organs. It is divided into:

3. A)- Pathogenic fungai infection: • Histoplasmosis • Blastomycosis • B)- Opportunistic fungi infection: • Candidiasis • Aspergillosis • Cryptococcosis • 4- Mycotoxicosis: by fungal toxins in food • Mushroom poisoning • Aflatoxin by Aspergillusflavus

4. Superficial mycosis Classification: 1- Pityriasisversicolor-------- Skin 2- Tineanigra-------------------Skin 3- Black pidera----------Hair 4- White pidera---------Hair

5. Pityriasisversicolor Causative agent: Malasseziafurfuris the causative agent of Pityriasisversicolor and Pityriasisfolliculitis. M. furfur is a lipophilic yeast living on the skin as part of the normal flora.

6. Clinical manifestations: • Pityriasisversicoloris associated with hyperpigmented or hypopigmentedlesions in patients. • A chronic, superficial fungal disease of the skin characterised by well-demarcated white, pink, or brownish lesions • Fungaemia: M. furfurhas also been reported as causing catheter acquired fungaemia

7. Laboratory diagnosis: Clinical material: Skin scrapings from patients with superficial lesions, blood and indwelling catheter tips from patients with suspected fungaemia. 2. Direct Microscopy: Skin scrapings taken from patients with Pityriasisversicolor stain rapidly when mounted in 10% KOH show characteristic clusters of thick-walled round, budding yeast-like cells and short angular hyphal forms up to 8um in diameter. These microscopic features are diagnostic for Malasseziafurfur and culture preparations are usually not necessary.

8. From skin biopsy From skin scrapping

9. 3. Culture: Culture is only necessary in cases of suspected fumgaemia. M. furfur is a lipophilic yeast, therefore in vitro growth must be stimulated by natural oils or other fatty substances. The most common method used is to overlay Sabouraud's dextrose agar containing cycloheximide (actidione) with olive oil or alternatively to use a more specialized media like Dixon's agar which contains glycerol mono-oleate (a suitable substrate for growth). 4. Serology: There are currently no commercially available serological procedures for the diagnosis of Malasseziainfections.

10. Management: The most appropriate antifungal treatment for pityriasisversicolor is to use a topical imidazole in a solution or lathering preparation. Ketoconazole shampoo has proven to be very effective.

11. Tineanigra A superficial fungal infection of skin characterised by brown to black macules which usually occur on the palmar aspects of hands and occasionally the plantar and other surfaces of the skin. The aetiological agent is Hortaeawerneckii a common saprophytic fungus believed to occur in soil, compost, humus and on wood in humid tropical and sub-tropical regions.

12. Laboratory diagnosis: 1. Clinical Material: Skin scrapings. 2. Direct Microscopy: Skin scrapings should be examined using 10% KOH. Skin scrapings mounted in 10% KOH showing pigmented brown to dark olivaceous (dematiaceous) septatehyphal elements and 2-celled yeast cells producing annelloconidia typical of Hortaeawerneckii.

13. 3. Culture: Clinical specimens should be inoculated onto primary isolation media, like Sabouraud's dextrose agar. 4. Serology: Not required for diagnosis. Management: Usually, topical treatment with Whitfield's ointment (benzoic acid compound) or an imidazole agent twice a day for 3-4 weeks is effective.

14. White piedra White piedra is a superficial cosmetic fungal infection of the hair shaft caused by Trichosporonbeigelii. Infected hairs develop soft greyish-white nodules along the shaft.

15. Laboratory diagnosis: 1. Clinical Material: Epilated hairs with white soft nodules present on the shaft. 2. Direct Microscopy: Hairs should be examined using 10% KOH. Look for irregular, soft, white or light brown nodules, 1.0-1.5 mm in length, firmly adhering to the hairs. 3. Culture: Hair fragments should be implanted onto primary isolation media, like Sabouraud's dextrose agar. Colonies of Trichosporonbeigelii are white or yellowish to deep cream colored, smooth, wrinkled, velvety, dull colonies with a mycelial fringe.

16. 4. Serology: Not required for diagnosis. Management: Shaving the hairs is the simplest method of treatment. Topical application of an imidazole agent may be used to prevent reinfection

17. Black piedra Black piedra is a superficial fungal infection of the hair shaft caused by Piedrahortae forming hard black nodules on the shafts of the scalp, beard, moustache and pubic hair.

18. Laboratory diagnosis: 1. Clinical Material: Epilated hairs with hard black nodules present on the shaft. 2. Direct Microscopy: Hairs should be examined using 10% KOH and Parker ink. Look for darkly pigmented nodules that may partially or completely surround the hair shaft. Nodules are made up of a mass of pigmented with a stroma-like centre containing asci. 3. Culture: Hair fragments should be implanted onto primary isolation media, like Sabouraud's dextrose agar. Colonies of Piedrahortae are dark, brown-black and take about 2-3 weeks to appear.

19. 4. Serology: Not required for diagnosis. Management: The usual treatment is to shave or cut the hairs short, but this is often not considered acceptable, particularly by women. In-vitro susceptibility tests have shown that Piedrahortae is sensitive to terbinafine and it has been successfully used