Microscopy and Culture of Skin, hair and nail

Microscopy and Culture of Skin, hair and nail

It is important that good quality samples are sent to the laboratory otherwise results may be misleading and repeat specimens indicated.

Skin and Nail Specimens should be collected into a Dermapak or similar black card packet. If these are not available then a sterile, plain, plastic universal may be used. Please do not use ad-hoc packets or sellotape as culture may fail due to overgrowth of contaminating saprophytic fungi. Microscopy will be impeded by specimen affixed to sellotape. If toothbrushes are used to sample scalp skin, please note this prevents microscopic examination of the sample. A scalp skin scraping or hair pluck is preferable.

Sample collection

Clean lesions with surgical spirit or 70% alcohol before collecting samples. This minimizes contamination and is an aid to microscopy if greasy ointments or powders have been applied

Be sure to include as much material as possible so that full laboratory investigations can be carried out. It is always useful to have enough skin or nail to repeat the culture if necessary

• Skin : Collect material by scraping from the edges of the lesions, ideally with a scalpel blade.
• Nail : If possible, collect the subungual debris in addition to nail clippings. Sample the discolored, dystrophic or brittle parts of the nail only, sampling as far back as possible from the distal part of the nail.
• Hair : Pluck hairs from the affected area with forceps (infected hairs come out easily) and scrape the scalp with a scalpel. Preferably, the sample should include hair roots, the contents of plugged follicles and skin scales. Hair cut with a scissors is unsatisfactory as the focus of infection is usually below or near the surface of the scalp. Sterile toothbrushes may be useful but preclude microscopy on the sample.

Storage of specimens

Skin and nail specimens should be stored at room temperature, as dermatophyte fungi may be killed at 4 - 6 ^oC. Swabs from mucous membranes should be stored in the refrigerator prior to dispatch.

Use(s):

Diagnosis of fungal infection by microscopy and culture.

Description:

Microscopy for yeasts, mycelium and other fungal elements; culture of any viable fungi present and identification of any clinically significant species. Antifungal susceptibility testing is undertaken where appropriate or requested.

Results:

Microscopy is reported as "No fungus seen" or positive with a description of the fungal cells seen.
Culture is reported as the identity of any significant fungi isolated.