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Culture Stool

As Known As: Fecal Culture, Enteric Pathogen Culture, Bacterial stool Culture


What Is Stool Culture Test?


It is a laboratory test that is used for isolation and identification of the type of pathogenic organisms in your stool sample to figure out the basic culprit of your symptoms and signs. Your gastrointestinal tract normally contains gut flora; these bacteria not only help in the digestion of food but also protect your gut from the invasion of pathogenic bacteria. Overgrowth of gut flora or reduction in their quantity both lead to gastrointestinal problems. A healthy immune system usually fight-off the minor digestive infection. Still, with a weakened or impaired immune system, you may need antibiotics to treat the infection, including infants, older adults, and people with HIV/AIDS.


A laboratory technician will place a small amount of your stool sample in a sterile plastic dish containing nutrients that encourages the growth of specific pathogenic bacteria and watch for the growth of a colony of that bacterium. When a colony is produced, they observe them under the microscope to detect the type of bacteria causing the disease.


What Is The Test Used For?


The test is used to determine the causative agent of your digestive tract illness. A wide variety of bacteria can cause gastrointestinal tract infections. The test can detect bacteria like Salmonella, Shigella, Campylobacter, Yersinia, Vibrio Cholera, Enterohemorrhagic E.Coli, and Clostridium difficile. You may become infected with these bacteria by eating or drinking contaminated food and water, maintaining poor hygiene and sanitary conditions, traveling to endemic areas, and sometimes due to prolonged use of broad-spectrum antibiotics. Signs and symptoms of the gastrointestinal tract may include:


  • Abdominal pain and cramping
  • Tenesmus
  • Diarrhea that lasts more than a few days
  • Severe watery diarrhea
  • Stool containing blood and mucous
  • Fever
  • Nausea and vomiting
  • Loss of appetite
  • Weight loss
  • Dehydration


Not everyone with these symptoms needs to be tested, as your immune system fights them off in healthy individuals.


When And Why Do You Need To Get Tested?


This is a painless, quick, and relatively easy method to find out the infective cause of your digestive symptoms. Your healthcare practitioner may request this test:


  • If you experience any of the above-mentioned signs and symptoms of the gastrointestinal tract which are becoming chronic, severe, and persistent.
  • If your symptoms are getting worse or not going away with empirical treatment.
  • If you have a recent history of traveling to an endemic area.
  • If you have a recent history of prolonged use of antibiotics and you are an older adult, these factors increase the likelihood of Clostridium difficile as the cause of diarrhea.
  • If your stool DR suggests the presence of fecal leukocytes.
  • If complications are developing like dehydration, electrolyte imbalance, and CNS symptoms like dizziness and drowsiness.
  • If you have weak immunity like in infants and older adults or have known immunodeficiency conditions like HIV/AIDS.
  • A repeat test may be ordered to detect the bacteria after the completion of the treatment, to verify that you are no longer infected with pathogenic bacteria, as in some cases, you may become a carrier. A carrier is not ill themselves, but they shed bacteria in their stool and can infect others.


Your healthcare practitioner may order some other tests along with this test to reach the definitive diagnosis and to initiate appropriate treatment.


What Kind Of Sample Is Required?


A small amount of fresh stool sample is required to collect in a laboratory-provided container. The sample should not be contaminated with toilet water, urine, or toilet paper and should be transported to the laboratory within 2 hours of collection of the sample.


A rectal swab may also be used for sample collection. A culture collection swab is passed beyond the anal sphincter, carefully rotated there, and withdrawn. This swab is then placed in a stool culture transport vial and shipped to the laboratory. The rectal swab is not as good as stool culture in detecting a carrier state.


If you face a problem producing a sample, a green salad or high fiber diet may help your digestive tract move along.


Do You Need To Prepare For This Test?


You don’t need any preparation for this test; however certain medications may interfere with the test result, including antibiotics, enema, laxatives, multivitamins, or any illicit drugs. You should inform your healthcare provider about them before running this test. Your healthcare provider may also ask you certain questions about your recent travel history and what you ate in the last 48 hours to rule out the food-borne cause of your illness.


Are There Any Risks To This Test?


There is no risk associated with fecal culture test; however, your stool may contain infectious agents that you can spread to other individuals. Be sure to thoroughly wash your hands with soap and water after collecting your stool sample.


What Does The Test Results Mean?


The test result is usually generated between 3-5 days and is reported as positive or negative.

A positive result suggests that you are infected with a pathogenic bacteria, which is the most likely cause of diarrhea. A positive result is frequently reported with the name of bacteria isolated from the specimen. The most commonly involved bacteria include;


  • SALMONELLA: found in raw egg and poultry, contaminated fruits and vegetables, and reptiles. It causes typhoid fever.
  • CAMPYLOBACTER: found in unpasteurized milk and uncooked poultry. It can lead to serious conditions if it spreads to the blood. It can occasionally cause long-term complications of arthritis and Guillain-barre syndrome.
  • SHIGELLA: spread through contaminated food and water with stool.
  • E.COLI: most strains of E.Coli are considered the normal gut flora, but some strains like Enterohemorrhagic strain, E.Coli 0157:H7, and other toxin-producing strains can cause bloody diarrhea and hemolytic uremic syndrome.
  • CLOSTRIDIUM DIFFICILE: a toxin-producing bacteria, usually present as normal gut flora, but prolonged use of broad-spectrum antibiotics can result in their over-growth, which leads to serious diarrhea and complications. Other specific tests may be required for diagnosis, including PCR or antigen tests.
  • VIBRIO CHOLERA: spread through contaminated food and water. It causes watery diarrhea, which can result in severe dehydration.


A negative test result reflects that no pathogenic bacteria are isolated from your stool sample. Your healthcare provider may repeat the same test or order some new tests to teach the diagnosis.


You should consult your healthcare provider if you have any queries regarding your test result. 


Related Tests:


  • Ova and parasite stool test
  • Stool test for H.pylori antigen
  • Stool fat test
  • Clostridium difficile stool antigen test

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