What is a stool
A stool culture can help your doctor understand and treat
problems with your digestive tract, or gastrointestinal tract. There are many
reasons why you might experience uncomfortable digestive symptoms. In some
cases, bacterial infections are the cause. Your doctor can order a stool
culture to check a sample of your stool, or feces, for harmful bacteria.
A stool culture is different from an ova and
parasite analysis of the stool. Sometimes it is necessary for the
laboratory staff to analyze someone’s stool under a microscope to see if any
ova (eggs) and parasites can be seen.
In a stool culture, laboratory staff will grow, or “culture,”
bacteria living in your stool. This can help them learn if any disease-causing
bacteria are present. They will smear a sample of your stool on special plates.
Those plates will contain a gel that acts as a growth media and will support
the growth of bacteria. Then laboratory staff will try to identify the bacteria
they find, using dye staining, microscope analysis, and other testing.
For example, laboratory staff may look for the following
bacteria in your stool:
- Campylobacter species
- Salmonella species
- Shigella species
If you’ve recently travelled outside of the United States or
have other risk factors, they may also check for:
- Vibrio species
- Escherichia coli 0157:H7 (a type of E. coli)
- Yersinia entercolitica
They may also perform other tests, including a test for the Clostridium
difficile (C. difficile) toxin or an ova and
parasite exam to look for parasites.
is a stool culture performed?
Infections of your digestive tract can cause uncomfortable
symptoms. In some cases, they can even be life threatening. Many different
infections cause similar symptoms, such as:
- nausea and vomiting
- abdominal pain and cramping
- severe diarrhea that has you going to the bathroom
every 30 minutes
- blood in your stool
Testing your stool for harmful organisms can help your
doctor identify the cause of your symptoms. A stool culture can help them learn
if harmful bacteria are present. It may also help them learn which treatments
may kill those bacteria.
is a stool culture performed?
To conduct a stool culture, your doctor will need to collect
a sample of your stool. They will likely give you a sample container to collect
it. This is usually a clean, dry, wide-mouth container with an airtight lid.
Some labs even include a special kind of toilet paper that can be used to
collect your sample. Alternately, you may be asked to provide your own sample
You can use a bedpan or other large container to collect
your stool sample. You can also collect a stool sample by loosely placing
plastic wrap over your toilet seat before defecating. Then you can use the
plastic wrap to transfer the sample into your collection container. Try to avoid
mixing urine or regular toilet paper into the sample.
The stool collection process can be more difficult with
infants in diapers or people with active diarrhea. If you’re collecting a stool
sample from your baby, your doctor may advise you to use a cotton swab to
collect a sample from their rectum. They may also advise you to place plastic
wrap in their diaper to collect a sample. It can be tricky to collect a sample
that’s free of urine. Ask your doctor for tips.
Your sample must be sent to a laboratory for culturing as
soon as possible. At the lab, technicians will smear a sample of your stool
onto plates containing gels that encourage bacterial growth. They will
examine the bacteria that grow under a microscope. They may stain them with
special dyes to help them identify the types of bacteria that grow. They may
also expose the bacteria to drugs that could potentially kill them. This can
help them learn what treatments may be effective.
The laboratory will send the results of your stool culture
to your doctor.
What do the results
Your doctor can help you understand the results of your stool culture. They
can also recommend appropriate follow-up steps, which may include treatment or
If harmful bacteria are found in your stool, your doctor may prescribe
antibiotics or other treatments. If no dangerous
bacteria are found, your symptoms may be due to other causes. Your doctor may
order more follow-up tests or examinations. For example, they may look for
signs of irritable
bowel syndrome, parasitic
infection, or other problems.
cultures: A healthy gut
When you’re healthy, a variety of “good” bacteria and other
organisms live inside your intestines. This normal flora is sometimes called
your microbiome. It helps to maintain your health. When you become infected
with disease-causing organisms, they can kill off good bacteria in your
intestines and make you sick.
Taking broad-spectrum antibiotics can also leave you
vulnerable to disease-causing organisms. These antibiotics kill off bacteria in
your intestines, including your normal flora or good bacteria. In some cases,
your normal flora may not reestablish themselves after a course of antibiotics.
This can leave you open to opportunistic infections.
Potentially harmful bacteria that are antibiotic-resistant
can survive and take over your digestive tract. For example, C.
difficile is one of those harmful bacteria. C.
difficile infections can be very difficult to treat. They can cause
pseudomembranous colitis. This condition is an uncomfortable and potentially
life-threatening inflammation of your colon.
A new and exciting treatment for C.
difficile is fecal bacteriotherapy. This is also called a stool
substitute transplant. In this procedure, a stool sample from a healthy person
is implanted into your colon. In a similar procedure, a purified bacterial
culture may be implanted in the same way. The good bacteria from donor stool or
a purified culture can recolonize your colon. This can help you recover from a
persistent C. difficile infection.