Dermatophyte: Introduction, lab diagnosis and treatment

Dermatophyte

Dermatophyte is a  pathogenic fungus that grows on skin, mucous membranes, hair, nails, and other body surfaces, causing ringworm and related diseases.. It is a group of three genera Trichophyton, Microsporum and Epidermophyton. It causes infection called ringworm. Clinically ringworm is of following types depending on the site of body involved. Tinea axillaries (axilla),tinea barbae(beard area),tinea corporis(non-hair skin),tinea capitis( hanir and scalp),tinea cruris(groin),tinea pedis(foot).The most common ringworm in human is due to Trichophyton rubrum.

Case report

A 33 years old , male  patient with complain of itching in groin region came in Derma OPD,  dermatologist checked the patient. Doctor got ringworm and thus suggested him for potassium hydroxide (KOH) mount and also for fungal culture.

Potassium hydroxide (KOH) mount report:

Potassium hydroxide (KOH) preparation of a skin scale, showing ringworm fungi with branching hypahe as shown above picture.

Impression: Branching fungal hyphae seen

Doctor advised him to use clotrimazole cream as medication and follow up after two weeks.

Finally , patient got rid off fungal infection.

Clotrimazole uses to treat skin infections such as ringworm and candidiasis. This cream  is also using to treat a skin condition known as pityriasis (tinea versicolor), a fungal infection that causes a lightening or darkening of the skin of the neck, chest, arms, or legs. Clotrimazole is an azole antifungal that works by preventing the growth of fungus. This is reason, patient benefited in this case.

Laboratory Diagnosis

Laboratory diagnosis is useful for identification of dermatophytes.

Potassium hydroxide (KOH) mount

Culture and sensitivity

If there is fungal growth, Lactophenol Cotton Blue (LPCB) preparation is necessary.

Similarly,  biochemical tests are also necessary to conform fungi in species level.

From the above case-

Potassium hydroxide (KOH) mount is with branching hyphae

similarly, growth of dermatophyte on Dermatophyte Test  Medium (DTM) observed after 14 days due to being slow grower as shown above figure.

Lactophenol Cotton Blue (LPCB) preparation is showing fungal structures i.e. microconidia, macroconidia ,hypahe resembling to Trichophyton species.

To go with species level biochemical tests are necessary.

Treatment

On the basis of type infection, treatment is of either topical or oral.

Tinea manus (hands), tinea corpora (body), tinea cruris (groin), tinea pedis (foot) and tinea facie (face) treates topically.

Tinea unguum (nails) usually will require oral treatment with terbinafine, itraconizole, or griseofulvin. Griseofulvin is usually not as effective as terbinafine or itraconizole. Tinea capitis (scalp) treats  orally, as the medication must be present deep in the hair follicles to eradicate the fungus. Usually griseofulvin gives orally for 2 to 3 months. Clinically dosage up to twice the recommended dose might use due to relative resistance of some strains of dermatophytes.Tinea pedis is usually treated with topical medicines, like ketaconazole or terbinafine , and pills, or with medicines that contains miconazole, clotrimazole. Antibiotics may be necessary to treat secondary bacterial infections that occur in addition to the fungus i.e. from scratching.Tinea cruris (groin) should be kept dry as much as possible.

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