Superficial Mycosis.pptx

Superficial Mycosis

1. Dr. Arun Kumar Parthasarathy Ph.D Dept. of Microbiology D.Y Patil Medical College, Kolhapur Superficial Mycosis

2. Fungal infection in human can be classified according to the tissues involved Superficial Mycosis Subcutaneous mycosis Systemic mycosis Opportunistic mycosis Fungal infection in humans are broadly classified into two types depending on the tissue affected Superficial and Deep mycosis

3. Superficial Mycosis Surface Infections Fungi live exclusively on the dead layers of the skin and its appendages They have no contact with living tissue and no elict inflammatory response Only changes produced are cosmetic effects Example:- Tinea (Pityriasis versicolor), Tinea nigra and pidra Cutaneous infection Infection generally confined to the cornified layer of the skin and appendages Various inflammatory and allergic responses are induced in the host by the presence of fungus and by their metabolic products Dermatophytosis caused by a group of fungi called the Dermatophytes

4. Superficial Mycosis Pityriasis versicolor ( Tinea versicolor ):- Chronic, usually asymptomatic involvement of the stratum corneum Distribution:- Worldwide distribution More prevalent in tropics Occurs mainly in young adults Causative agent:- Malassezia furfur (formerly Pityrosporum orbiculare ) Lipophilic, yeast –like fungus

5. Clinical features:- Characteristic discrete or confluent macular areas of discolorisation or depigmentation occur on the skin of the chest, abdomen, upper limbs and back. The fungus may be demonstrated on normal skin and the disease may be considered an opportunistic infection. Diagnosis:- Examination of skin scrapings shows an abundant of yeast like cells and short, branched filaments. The fungus can grown on Sabouraud dextrose agar covered with layer of olive oil.

6. Tinea nigra Localized infection of stratum corneum, particularly of the palms, producing black or brownish macular lesions Distribution:- Mainly occurs in Tropics Causative agent:- 1. Exophiala werneckii (formerly Cladosporium wernickii , Hortea wernickii ) 2. Exophiala castellanii Diagnosis:- Skin scraping show brownish, branched, septate hyphae and budding cells. Colonies on Sabouraud dextrose agar are grey or black in color.

7. Piedra Fungal infection of hair Characterized by the presence of firm, irregular nodules along the hair shaft, These nodules composed of fungal elements cemented together on the hair 2 varieties of Piedra are recognized Black piedra - Piedraia hortae White piedra – Trichospora beigelii

8. Cutaneous Mycoses (Dermatophytoses) Dermatophytoses (commonly called tinea or ringworm) refers to infection of keratinized structures (Hair, Nail and Skin). Caused by group of Ketaniophilic fungi called Dermatophytes Infection may be acute or chronic Chronic course with episodes of remission and exacerbation Characteristics of Dermatophytes:- Hyaline filamentous fungi that digest keratin by enzymatic but unable to invade living tissue Variety of pathological changes occur in the infected host because of fungi and their metabolic products Resist to chlorhexidine Classified into 3 groups depending on their usual habitat.

9. Genera of Dermatophytes 3 genera of Dermatophytes Microsporum (16) - M. gypseum, M.canis, M.nanum Trichophyton (24)– T.rubrum, T.mentagrophytes, T.verrucosum Epidermatophyton (1) - E. floccosum About 40 species of Dermatophytes are known to cause infections in humans and animals

10. Clinical aspects of Dermatophytosis More common in males than females Clinical classification is according to the anatomical site involved Tinea barbae (barber’s itch)- involves the bearded area of the face and neck Tinea corporis ( Tinea glabrosa )- ringworm of smooth or non-hairy skin of the body Tinea imbricata- special type of T.corporis found in tropics, characteristics extensive concentric rings of papulosquamous scaly patches Tinea capitis- ringworm of scalp, favus and Kerion are variants Tinea cruris (jock itch)- involves the groin and perineum Tinea pedis (athlete’s foot)- ringworm of the foot Tinea manuum- involves the hand Tinea unguium- involves the nails

11. Dermatophytoses-Causative agent Sr.No Disease Common causative agents 1 Tinea capitis Microsporum species Trichophyton species 2 Favus Microsporum gypseum Trichophyton schoenleinii Trichophyton violaceum 3 Tinea barbae Trichophyton rubrum Trichophyton mentagrophytes Trichophyton verrucosum 4 Tinea imbricata Trichophyton concentricum 5 Tinea corporis Trichophyton rubrum and other Dermatophytes 6 Tinea cruris Epidermatophyton floccosum Trichophyton rubrum 7 Tinea pedis Epidermatophyton floccosum Trichophyton rubrum

12. Clinical features:- Lesion in the skin tend to be circular, dry, erythymatous, scaly and itchy Lesions of the hair include Kerion, scarring and alopecia Favus:- A chronic type of ringworm in which dense crusts (Scutula) develop in the hair follicles, leading to alopecia and scarring Kerion:- sever boggy lesions with marked inflammatory reaction that sometimes develops in scalp due to Dermatophytes Nails infected by Dermatophytes are deformed, friable and discolored and there is accumulation of debris under the nails. In lesions Dermatophytes appear as hyphae and arthrospores

13. Pathogenicity Dermatophytes grow only on the keratinized layer of the skin and its appendages Do not ordinarily penetrate living tissue Mechanisms of pathogenesis are unclear Fungal products may responsible for inciting local inflammation Hypersensitivity of fungal infection may play a vital role and may be responsible for sterile vesicular lesions The reaction may follow oral antifungal therapy and confused with an allergic drug reaction Called dermatophytids (or id reactions) Hypersensitivity can be demonstrated by skin testing with fungus antigen trichophytin

14. Laboratory diagnosis Specimens:- Scraping of skin and nail Short length of plucked hair from scalp Scraping are taken from the edges of ringworm lesions Direct Microscopy examination:- 10-20% KOH wet mount preparation Suspected Tinea capitis, fungal elements looked by exposure to UV light (wood’s lamp examination). Infected hair will fluorescent 2 types of hair infection may be distinguished in wet mounts Ectothrix- arthrospores are seen as a sheath surrounding the hair Endothrix- arthrospores are inside the hair shaft

15. Culture:- Sabouraud glucose neopeptone agar containing Chloramphenicol Sabouraud dextrose agar containing Chloramphenicol and Cycloheximide Dermatophytes Test Medium (DTM) Cycloheximide –Inhibits the saprophyte molds, Gentamicin- and Chlortetracycline- Inhibit the bacteria Phenol Red- indicator changes yellow to red within 14 days when the medium is alkaline as a result of dermatophytes. Temp:- 25-30 ºC upto 21 days

16. Colony Character Trichophyton:- Colonies may be powdery, velvety or waxy with pigmentation characteristic of different species. Macroconidia- usually rare, elongated and blunt ends, smooth, thin walls & Variable in shape (Cylindrical, fusiform or clavate), vary in number of septa (2-8) and in size (20-50 X 4-6 µm). They are arranged in singly or in clusters Microconidia- abundant , arranged in clusters along the hyphae on conidiophores Hyphae:- Special type of hyphae , Spiral hyphae Racquet hyphae Favic chandeliers

17. Microsporum:- colonies are velvety, cottony or powdery with white to brown pigmentation Macroconidia - Numerous, typically thick walled and rough (varying from minutely to strongly roughened) Varying in shape ( fusiform to obovate ) No. of septa :- 3-15 and size:- 5-100 X 3-8 µm Microconidia- Scarce, pyriform or clavate, usually arranged in singly along the sides of the hyphae.

18. Epidermatophyton:- colonies are powdery and greenish yellow Microconidia- Absent Macroconidia- club shaped, 2-6 septa, Size:- 20-40 X 6-8 µm in size Thin and slightly thick walled and are singly or clusters

19. Trichophyton mentagrophytes White to tan, cottony or powdery pigment variable Trichophyton rubrum Velvety, red pigment on reverse Trichophyton violaceum Very slow growing , waxy, violet or purple pigment Microsporum canis Cottony, orange pigment on reverse Microsporum audouinii Velvety, brownish slow growing Microsporum gypseum Powdery buff colored Epidermatophyton floccosum Yellowish green, powdery Colony Character

20. Trichophyton mentagrophytes Clusters of microconidia , cigar shaped macroconidia with terminal rat-tail filaments Trichophyton rubrum Few, long , pencil shaped macroconidia Trichophyton violaceum Hyphal swelling, chlamydospores, favic chandelier, disorted hyphae, conidia rare. Identification

21. Microsporum canis Abundant thick walled spindle shaped macroconidia with upto 15 septa Microsporum audouinii Thick walled chlamydospores, conidia rare and irregular Microsporum gypseum Abundant thin walled macroconidia with 4-6 septa Epidermatophyton floccosum Club shaped macroconidia in clusters Identification

22. Cellophane tape mount

23. Hair Perforation test Useful in differentiating Trichophyton rubrum from T.mentagrophytes To observe hair perforation, short (5-10mm)strands of human hair placed in a Petri dish with 20 ml of autoclaved distilled water 2 or 3 drops of 10% sterilized yeast extract are added to the petri dish Hair strands are inoculated with small fragments of test fungus grown of SDA Incubate at 25-30C and the hair stands are removed and observed microscopically at weekly intervals upto 1 month T.rubrum- surface erosin of hair shafts in this test T.Mentragrophytes – wedge shaped perforation perpendicular to hair shaft

24. Urease test Useful for distinguishing isolate of T.mentagrophytes from T.rubrum Urease splits urea in Christensen's medium, producing ammonia, which raises the pH and causes a color from amber to pink (Phenol red) T.mentagrophytes- produces bright pink color (positive) T.rubrum- No color change (Negative)