Dermatophyte: Tineas or ring worms (Mycoses) – Basic microbiology, parasitology, and immunology; nature, reproduction, growth, and transmission of common microorganisms and parasites in Bangladesh; prevention including universal precaution and immunization, control, sterilization, and disinfection; and specimen collections and examination. Students will have an understanding of common organisms and parasites caused human diseases and acquire knowledge about the prevention and control of those organisms.
Dermatophyte: Tineas or ring worms (Mycoses)
Dermatophyte:
A dermatophyte infection, also known as dermatophytosis or tinea, refers to a group of fungal infections that can affect the skin, hair, and nails.
Or,
Dermatophytosis is a contagious infection caused by fungi known as dermatophytes. It is also an inflammatory reaction in the host of the superficial tissues such as the epidermis, hair, and nails.
Or,
Dermatophytes are a group of fungi which are keratinophilic and have the ability to infect the skin and skin appendages i.e. hair & nail.
Properties/Features of Dermatophytes:
➤ They are keratinophilic, so infect keratin containing tissue i.e. skin, nail & hair.
➤ Utilize ‘keratin’ for metabolism.
➤ Cannot grow at 37°C, so they do not produce any systemic disease.
➤ They cannot grow in serum.
Types of Dermatophytosis:
Different types of dermatophytosis affect the body in different ways. Some types are mild, but some of them are serious. The common types of dermatophytosis include:
Tinea Pedis
Tinea pedis, also called Athlete’s foot, is a common skin infection of the feet caused by fungus.
Tinea Unguium
Tinea unguium, also known as Onychomycosis, is a fungal infection of the nail.
Tinea Corporis
Tinea corporis, also called tinca circinata and tinea glabrosa, is a superficial fungal infection of the arms and legs, especially on glabrous skin.
Tinea Cruris
Tinea cruris, also referred to jock itch, is a fungal infection in the groin area in either sex, but more often in males. The infection results in itching or a red with flaking skin.
Tinea Manuum
Tinea manuum or tinea manus, is a fungal infection of the hand. It is more aggressive than tinea pedis but similar to in look. The observed symptoms in tinea manuum patients are itching, burning, cracking, and scaling.
Tinea Capitis
Tinea capitis, also known as herpes tonsurans and scalp ringworm, is a cutaneous fungal infection of the scalp.
Tinea Barbae
Tinea barbae, also called Barber’s itch, is a fungal infection of the hair due to the infection around the bearded area of men.
Tinca Facici
Tinea faciei is a fungal infection of the face.
Tinea Versicolor
Tinea versicolor, also called pityriasis versicolor, is a fungal infection of the skin.
Tinea Nigra
Tinea nigra is a superficial mold infection of the stratum corneum that causes dark brown to black painless patches on the palms of the hands and the soles of the feet.
Transmission:
➤ Dermatophytes are transmitted by direct contact with an infected host (human or animal) or by direct or indirect contact with infected shed skin or hair in fomites such as clothing, combs, hair brushes, theatre seats, caps, furniture, bed linens, shoes, socks, towels, hotel rugs, sauna, bathhouse, and locker room floors. Also, transmission may occur from soil-to- skin contact. Depending on the species the organism may be viable in the environment for up to 15 months.
➤ While even healthy individuals may become infected, there is an increased susceptibility to infection when there is a preexisting injury to the skin such as scars, burns, excessive temperature and humidity. Adaptation to growth on humans by most geophilic species resulted in diminished loss of sporulation, sexuality, and other soil-associated characteristics.
Lab, diagnosis:
Principle; Diagnosis is based on the demonstration of fungal structure on the specimen by microscopic examination, and isolation and identification of fungus from culture.
Steps:
Specimen:
➤ Skin-scrapping
➤ Nail – Clipping
➤ Hair-Plucking
Microscopic examination: Dissolve the specimen in KOH solution.
➤ Skin-10% KOH for at least 1 hour
➤ Hair-20% KOH for at least 10 hours
➤ Nail-40% KOH for at least 10 hours
Findings:
➤ Skin & nail: Septate hyphae with arthrospore.
➤ Hair: Ectothrix (fungal spores outside the hair shaft) and endothrix (fungal spores inside the hair shaft).
Isolation & identification from culture:
➤ Specimen is incubated in Sabouraud’s dextrose agar media at 25 30°C (room temp.) for 3-4 weeks.
Findings:
➤ Naked eye:
- Colour: Green, red, white and brown.
- Texture: Cottony, powdery and velvety appearance.
➤ Microscopic examination from colony:
- Microconidia & macroconidia
Treatment:
A) Topical drugs:
➤ Whitfields ointment
➤ Antifungal creams: Miconazole, clotrimazole, terbinafine, econazole – Apply 2 or 3 times/day for 2-4 weeks.
➤ Antifungal shampoo: 2% Ketoconazole, two to three times weekly for 2-4 weeks
B) Systemic drugs (for extensive infections):
➤ Griseofulvin 500 gm daily for 2-6 weeks for skin and hair involvement, 6 months in nail involvement or
➤ Fluconazole 50 mg daily for 6 weeks
Ringworm
Definition: Ringworm is the skin infection caused by a fungus.
Site of involvement:
➤ Trunk or whole body (tinea corporis)
➤ Scalp (tinea capitis)
➤ Groin area (tinea cruris)
➤ Feet (tinea pedis)
➤ Nails (tinea unguium)
➤ Beard (tinea barbae)
Mode of transmission:
➤ Direct skin to skin contact with an infected person or pet
➤ Indirect contact with object or surface that an infected person or pet has touched such ascaps, combs, brushes, bed linens, telephones etc.
➤ Incubation period: 10-14 days after contact. Ringworm of the skin appears 4 – 10 days after contact
Clinical features:
➤ Ring worm of the scalp or beard usually begins as a small pimple that becomes larger, leaving scaly patches of temporary baldness. Infected hairs become brittle and break off
easily.
➤ Ringworm of the body shows up as a flat, red and itchy round patch anywhere on the skin except for the scalp and feet. The groin is a common area of infection. As the rash gradually expands, its center clears to produce a ring.
➤ Ringworm of the foot is also called athletes foot. It appears as a scaling or cracking of the skin, especially between the toes.
Treatment:
C) Topical drugs:
➤ Whitfields ointment
➤ Antifungal creams: Miconazole, clotrimazole, terbinafine, econazole – Apply 2 or 3 times/day for 2-4 weeks.
➤ Antifungal shampoo: 2% Ketoconazole, two to three times weekly for 2-4 weeks
D) Systemic drugs (for extensive infections):
➤ Griseofulvin 500 gm daily for 2-6 weeks for skin and hair involvement, 6 months in nail involvement or
➤ Fluconazole 50 mg daily for 6 weeks
Complication of ringworm:
➤ Cracking or eroding of the skin between toes and fingers
➤ Eczematous change of the involved area
➤ Allergic dermatitis
➤ Secondary bacterial infections can develop in cracked skin or in hair follicles
Preventive and controlling measures of ringworm
➤ Educate the public, especially parents, about the risk of ringworm form infected person and pets.
➤ Keeping common use areas clean, especially in schools, day care centers, gyms, and locker rooms. Disinfect sleeping mats and gym mats after each use.
➤ Keep the skin clean and dry
➤ Infected person should follow these steps to keep the infection from spreading
➤ Complete treatment as instructed, even after symptoms disappear
➤ Do not share towels, caps, clothing, hair brushes, or other personal items with others minimize close contact with others until treated
➤ Make sure the person or animal that was the source of infection gets treated
Read More….