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Anaerobic Culture

Does this test have other names?

Wound culture

What is this test?

This test looks for certain bacteria in a wound or an infection in a fluid sample. These bacteria are called anaerobic because they don't need oxygen to grow.

Infections caused by anaerobic bacteria can occur almost anywhere in your body. These may be oral infections, lung infections, diabetes-related foot infections, infected bites, and gangrene. Identifying the specific bacteria that's causing your infection helps your doctor choose the appropriate treatment.

This test takes up to a week for results. That's because any bacteria from the sample need time to grow so they can be looked at in a lab. An anaerobic culture means the test is done without exposing the sample to oxygen.

Why do I need this test?

You may need this test if your doctor needs to find out the type of bacteria that's causing an infection in your body. Your doctor may order this test based on the location of the wound, tissue damage, unpleasant smell from the wound, or an infection-related abscess.

You may also have this test to see whether treatment for an infection is working.

What other tests might I have along with this test?

Your doctor may also order other tests, depending on your symptoms. These tests include:

  • Gram stain

  • Complete blood count, or CBC

  • Blood culture

  • Urine culture

  • Stool sample

  • MRSA screening

  • Imaging studies, such as ultrasound or CT scan, to find areas of infection or damaged tissue

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

Normal results are negative, meaning that no bacteria grew in your fluid sample. You may still have an infection, however, because anaerobic bacteria are difficult to grow in the lab.

A positive result means that bacteria grew in your fluid sample. But the bacteria that grow in a culture may not necessarily be the ones causing your infection.

How is this test done?

This test requires a sample of pus from your wound or abscess. Your doctor may use a large cotton swab to get the sample. But larger samples give better information, so your doctor may use a needle to draw fluid from your wound.

Does this test pose any risks?

This test poses few risks. You may have pain or discomfort when your health care provider collects the sample.

What might affect my test results?

Anaerobic bacteria are difficult to grow, and some bacteria may not grow in this test. This means you may have a false-negative result. Anaerobic bacteria picked up in the sample that are present in the area of the infection but are not causing the infection can also affect your results.

How do I get ready for this test?

You don't need to prepare for this test.  But be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.