Subcutaneous tissue and skin specimens

            1.   Burn specimens

                  The surface of burn wounds will become colonized by the patient's microflora or by environmental organisms. When the organism load is large, infection of underlying tissue may occur, and bacteremia may ensue. Cultures of the surface alone are misleading; therefore, biopsies of deeper tissue are often indicated. Additionally, organisms may not be distributed evenly in the burn wound, so sampling of different areas of the burn is recommended.

                  a.   Disinfect the surface of the burn with 70% alcohol and then with  a 10% solution of povidone-iodine. Allow the disinfectant to dry prior to collecting the specimen. Note: Blood cultures should be used to monitor patient status. 

                  b.   Collect a punch biopsy sample (3 to 4 mm) for quantitative culture. Transport to lab without addition of saline in sterile container.

            2.   Superficial wound, bacterial

                  a.   Syringe aspiration is preferable to swab collection.

                  b.   Disinfect the surface of the wound with 70% alcohol and then with a 10% solution of povidone-iodine. Allow the disinfectant to dry prior to collecting the specimen.

                  c.   Using a 3 to 5 ml syringe directly or with a 22 to 23 gauge needle, a physician will aspirate the deepest portion of the lesion. If a vesicle is present, collect both fluid and cells from the base of the lesion.

                  d.   If the initial aspiration fails to obtain material, inject sterile, nonbacteriostatic 0.85% NaCl subcutaneously.

                  e.   Repeat the aspiration attempt.

            3.   Superficial lesions, fungal

                  a.   Clean the surface with sterile water.

                  b.   Using a scalpel blade, scrape the periphery of the lesion border.  Samples from scalp lesions should include hair that is selectively collected for examination. If there is nail involvement, obtain scrapings of debris or material beneath the nail plate. Transport in a sterile container.

            4.   Ulcers and nodules

                  a.   Clean the area with 70% alcohol and then with a 10% solution of povidone-iodine.

                  b.   Remove overlying debris.

                  c.   Curette the base of the ulcer or nodule.

                  d.   If exudate is present from ulcer or nodule, collect it with a syringe or sterile swab.

           

Table 10 - Collection considerations for subcutaneous tissue and skin specimens

      ^aRate of recovery of HSV and varicella-zoster virus is highest from the youngest lesions (vesicles), then from pustules, ulcers, and crusted lesions, in that order.