Patient education: Bacterial wound culture (The Basics)

What is a bacterial wound culture? — This is a lab test. It is a way to check a wound for bacteria that could be causing an infection.

For a wound culture, a doctor or nurse takes a sample of cells from a wound. The sample is sent to a lab, where they add a special substance that causes bacteria to grow. If there are bacteria in the wound, these will show up within a few days.

Why might I get a bacterial wound culture? — Your doctor might order a wound culture:

●If you have signs of infection after getting a wound – A "wound" means something that cut open or broke the skin. This could be an injury like a cut, scratch, or bite. Or it could mean a cut made in the skin during surgery. Signs of infection might include swelling, pus, red streaks on the skin, or a bad smell. Wound infection can also cause symptoms like fever, chills, dizziness, or confusion.

●To help decide what antibiotics to prescribe – A culture can show what kind of bacteria are causing an infection. This is important for deciding how to treat it.

How do I prepare for a bacterial wound culture? — You do not have to do anything special to prepare. Your doctor or nurse might ask you about medicines you take. This includes any recent antibiotics, such as pills, creams, or ointments.

What happens during a bacterial wound culture? — To do a wound culture:

●The doctor will carefully clean the area around the wound. They might need to first remove some stitches, or remove damaged or dead tissue. If needed, they will use medicine to numb the area so this doesn't hurt.

●They will use a swab to get a small sample of fluid and cells from the wound. Sometimes, they can take the sample from the surface of the wound. Other times, they might need to get cells or tissue from deeper inside the wound.

●They will send the sample to a lab. The staff will look at the sample under a microscope to see if bacteria grow. They can also do tests to figure out the type of bacteria. This usually takes at least 1 to 2 days.

●They will cover your wound with a clean bandage if needed.

What do my results mean? — Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or if you use an online "patient portal," you might get an alert there when your results are ready.

●If your wound culture is "positive," this means that you do have bacteria in your wound. Your doctor or nurse will talk to you about what to do next. If you have an infection, your doctor will prescribe an antibiotic based on what type of bacteria was found.

●If your wound culture is "negative," this means that you do not have bacteria in your wound. If you have symptoms of infection but your wound culture is negative, your doctor or nurse might want to repeat the wound culture or do other tests to try to figure out the cause.

What else should I know?

●Follow all of your doctor's instructions for keeping your wound clean. Wash your hands before and after touching your wound or bandage.

●Call your doctor or nurse if you have any new signs of infection. These can include:

•Fever

•Redness, swelling, warmth, or increased pain around the wound

•A bad smell coming from the wound

•Pus (thick yellow, green, or gray fluid) draining from the wound

•Red streaks on the skin around the wound, or red streaks going up your arm or leg

More on this topic

Patient education: Taking care of cuts, scrapes, and puncture wounds (The Basics)
Patient education: Animal and human bites (The Basics)
Patient education: Surgical site infection (The Basics)
Patient education: Caring for an open surgical wound (The Basics)
Patient education: Caring for a closed surgical wound (The Basics)

Patient education: Animal and human bites (Beyond the Basics)