Health Guide

Direct burn culture

What is this test?

This test detects and isolates microorganisms from a burn site. This test is used to monitor for a suspected bacterial infection of the skin in burn patients. A sample of wound material, drainage, or skin from a burn site may be collected for this test [1][2][3][4][5].

What are related tests?

  • Biopsy of skin

Why do I need this test?

Laboratory tests may be done for many reasons. Tests are performed for routine health screenings or if a disease or toxicity is suspected. Lab tests may be used to determine if a medical condition is improving or worsening. Lab tests may also be used to measure the success or failure of a medication or treatment plan. Lab tests may be ordered for professional or legal reasons. You may need this test if you have:

  • Bacterial infection of skin

When and how often should I have this test?

When and how often laboratory tests are done may depend on many factors. The timing of laboratory tests may rely on the results or completion of other tests, procedures, or treatments. Lab tests may be performed immediately in an emergency, or tests may be delayed as a condition is treated or monitored. A test may be suggested or become necessary when certain signs or symptoms appear.

Due to changes in the way your body naturally functions through the course of a day, lab tests may need to be performed at a certain time of day. If you have prepared for a test by changing your food or fluid intake, lab tests may be timed in accordance with those changes. Timing of tests may be based on increased and decreased levels of medications, drugs or other substances in the body.

The age or gender of the person being tested may affect when and how often a lab test is required. Chronic or progressive conditions may need ongoing monitoring through the use of lab tests. Conditions that worsen and improve may also need frequent monitoring. Certain tests may be repeated to obtain a series of results, or tests may need to be repeated to confirm or disprove results. Timing and frequency of lab tests may vary if they are performed for professional or legal reasons.

How should I get ready for the test?

Wound material/drainage:

Before a wound culture, you may be offered medication for pain. You will need to have your body in a position to allow the healthcare worker access to the wound.


Written consent may be required for a skin biopsy. Review the consent form with the healthcare worker and ask any questions that you have before signing the consent form.

Tell the healthcare worker if you have a medical condition, or are using a medication or supplement that causes excessive bleeding. You should also report if you have a history of allergic or other reactions to local anesthetics.

How is the test done?

A sample of wound material, drainage, or skin may be collected for this test[2][3].

Wound material/drainage:

A wound culture sample may be made up of cells, tissue, or fluid. Methods used to obtain a wound culture vary depending on many factors, including the location and type of wound. Before the procedure, the healthcare worker will usually clean the area with antiseptic solution, and place sterile cloth around the wound. To collect a sample from certain wounds, the healthcare worker will press or squeeze near or on the wound and use a sterile swab to gather fluid, cells, or tissue. The swab may also be inserted deeply into the wound and rotated to collect a sample. For a deep wound, a needle and syringe may be used to draw material from the base of the wound for the sample.


Skin tissue biopsies may be collected using the excision, punch, or shave methods. After a biopsy site is selected and cleaned, local anesthetic will be given to numb the area. If excision is done, a scalpel is used to completely remove a skin area such as a growth or lesion. If the punch method is used, a hollow tool is rotated on the sample area to obtain a tiny core of tissue, which is then removed with tweezers. If the shave method is used, only tissue that sticks out above the skin line (such as a growth) will be removed.

How will the test feel?

The amount of discomfort you feel will depend on many factors, including your sensitivity to pain. Communicate how you are feeling with the person doing the procedure. Inform the person doing the procedure if you feel that you cannot continue with the procedure.

Wound material/drainage:

The amount of discomfort you feel will depend on many factors, including your sensitivity to pain. Communicate how you are feeling with the person doing the procedure. Inform the person doing the procedure if you feel that you cannot continue with the procedure.


Before the skin biopsy, a local anesthetic is given to the procedure site to numb the area. You may feel mild discomfort or stinging when the numbing medicine is injected. After the medication wears off, the biopsy area may be sore for several days.

What should I do after the test?

Wound material/drainage:

After a wound culture, follow the healthcare worker’s instructions regarding taking care of the wound. Call your healthcare worker if you have increasing pain, redness, swelling, discharge or bleeding from the wound. Inform them if you develop a fever, start vomiting, or have increasing fatigue.


After a skin biopsy is completed, pressure may be held on the area, and a dressing placed over the biopsy site. If the incision is large or deep, stitches, staples, or adhesive strips may be used to close the biopsy site. Ask for instructions for how to care for the bandage and how to monitor for signs and symptoms of infection. Contact your healthcare worker if you have a fever or increased pain, and if you see redness, swelling, or pus at the procedure site.

What are the risks?

Wound material/drainage: Ask the healthcare worker to explain the risks of this procedure to you before it is performed.

Skin tissue: A sample of skin tissue is collected by biopsy. Multiple methods and sites may be used for a biopsy. The risks for this procedure will vary depending on the method and location used to collect the sample. However, bleeding and infection are possible risks when having a skin biopsy. If you have medical condition, or are using a medication or supplement that causes excessive bleeding, you are at a higher risk of bleeding during or after this procedure. The person doing this procedure may need to perform it more than once. Talk to your healthcare worker if you have any concerns about the risks of this test.

What are normal results for this test?

Laboratory test results may vary depending on your age, gender, health history, the method used for the test, and many other factors. If your results are different from the results suggested below, this may not mean that you have a disease. Contact your healthcare worker if you have any questions. The following is considered to be a normal result for this test:

  • Adults and Children: Negative

What might affect my test results?

  • Results increased in [5]:
    • Sampling taken from pooled secretions or exudate or sloughing eschar (overgrowth)
    • Prolonged incubation of swab in transport media prior to analysis
  • Results decreased in [5]:
    • Sampling taken from a nonrepresentative desiccated area or area with residual topical agent (undergrowth)
    • Delay in transport to lab

What follow up should I do after this test?

Ask your healthcare worker how you will be informed of the test results. You may be asked to call for results, schedule an appointment to discuss results, or notified of results by mail. Follow up care varies depending on many factors related to your test. Sometimes there is no follow up after you have been notified of test results. At other times follow up may be suggested or necessary. Some examples of follow up care include changes to medication or treatment plans, referral to a specialist, more or less frequent monitoring, and additional tests or procedures. Talk with your healthcare worker about any concerns or questions you have regarding follow up care or instructions.

Wound material/drainage:

After a wound culture you may need to do wound care. Ask your healthcare worker for wound care instructions, including how often wound care should be done.


After a skin biopsy, healthcare workers may use stitches or staples to close the wound. A return appointment may be necessary to have the stitches or staples removed. Wound care may also be necessary. Ask your healthcare worker for instructions following the skin biopsy.

Where can I get more information?

Related Companies

  • Centers for Disease Control and Prevention -


[1] Elsayed S, Gregson DB, Lloyd T, et al: Utility of gram stain for the microbiological analysis of burn wound surfaces. Arch Pathol Lab Med 2003; 127(11):1485-1488.

[2] Sjoberb T, Mzezewa S, Jonsson K, et al: Comparison of surface swab cultures and quantitative tissue biopsy cultures to predict sepsis in burn patients: A prospective study. J Burn Care Rehabil 2003; 24:365-370.

[3] Tietz NW (Ed): Clinical Guide to Laboratory Tests, 3rd ed. W. B. Saunders, Philadelphia, PA, 1995.

[4] Kagan RJ & Warden GD: Management of burn wound. Clinics in Dermatol 1994; 12:47-56.

[5] Pruitt BA & McManus AT: Opportunistic infections in severely burned patients. Am J Med 1984; 76(3A):146-154.

Last Updated: 7/4/2018
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