What Is a Stool Culture?

If you’ve been having stomach problems, your doctor might order a stool culture or ask for a stool sample. This test can look in your poop for bacteria, a virus, or other germs that might be making you sick.

Why Do You Need It?

Your doctor could order this test if you show any of these symptoms:

Your doctor may be more concerned if:

  • You’re very young or elderly
  • You have a weakened immune system
  • You’ve traveled outside the United States
  • You’ve eaten contaminated food or water
  • Your symptoms are severe

You may need antibiotics to get rid of the infection or prevent other health problems, like dehydration (losing too much fluid).

How Is a Stool Culture Done?

You’ll need to give your doctor a sample of your poop. You won’t need to do this at the doctor’s office. Instead, you’ll be given a special container with a lid to take home. This may have your name and birthdate on it. If not, you can write it on the label.

Your doctor will go over how to collect the sample and any special instructions. In most cases, you’ll follow these steps:

Place something in your toilet to catch your poop. Your doctor may give you a small container or you could use a clean, empty plastic one that you have. If your stool isn’t loose or watery, you could also spread newspaper or plastic wrap over the toilet rim.

Make sure your poop doesn’t touch the inside of your toilet. It could pick up germs that aren’t yours.

Place the sample into the container. Don’t use your hands. Your doctor should give you a small spoon or spatula you can throw away after you use it.

Don’t overfill the container. For the test, you’ll only need to provide a sample that’s about the size of a walnut. Make sure to include any pieces that are bloody, slimy, or watery.

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Avoid getting urine mixed up with your stool. If you need to pee, do so before starting.

Put the container in a sealed plastic bag and wash your hands well with soap and water. Flush any leftover poop down your toilet.

Return the sample to your doctor’s office as soon as you can. It can be kept in your refrigerator until then, but for no more than 24 hours.

Tell your doctor about any medicines you’re taking, since these can affect your test results. He should also know if you’re taking any herbs, supplements, vitamins, over-the-counter, or illegal drugs.

When Do You Get the Results?

Once your sample gets to the lab, it will be smeared inside a special sterile plate that helps bacteria to grow. Any that does is looked at more closely under a microscope.

Most of the time, you should get results back within 1 or 2 days.

What Do the Results Mean?

If your test results are negative, that means that they’re normal. No germs were found in your poop and you don’t have an infection.

A positive test result means that your poop was infected with a germ, virus, or other type of bacteria. The lab will tell your doctor which type it is and which medicines will fight against it. That can help him decide how to treat it.

WebMD Medical Reference Reviewed by Carol DerSarkissian on January 22, 2017

Sources

SOURCES:

University of Rochester Medical Center: “Stool Culture.”

NHS Choices: “How should I collect and store a stool (faeces) sample?”

Labtestsonline.org/American Association for Clinical Chemistry: “Stool Culture.”

Kids Health from Nemours: “Stool Test: Bacteria Culture.”
Health Protection Scotland: “How to collect a faecal specimen at home.”

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