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Co-culture, also known as microbiological culture of feces, is an examination that aims to identify the infectious agent responsible for gastrointestinal changes, and is usually requested by the doctor when there is suspicion of infection by Salmonella spp., Campylobacter spp., Escherichia coli or Shigella spp.
To perform this examination, it is recommended that the person evacuate and take the stool properly stored to the laboratory within 24 hours for analysis to be carried out and the bacteria responsible for the gastrointestinal alteration to be identified, in addition to the bacteria that are part of normal gut microbiota.
What is it for
Co-culture serves to identify microorganisms that may be related to gastrointestinal changes, such as food poisoning or intestinal infection. Thus, this exam can be ordered by the doctor when the person has some of the following symptoms:
- Abdominal discomfort;
- Diarrhea;
- Nausea and vomiting;
- Fever;
- General malaise;
- Presence of mucus or blood in the stool;
- Decreased appetite.
In most cases, in addition to requesting co-culture, the doctor also requests a parasitological stool examination, which is an examination that identifies the presence of parasites in the stool that are also responsible for gastrointestinal symptoms, such as Giardia lamblia, Entamoeba histolytica, Taenia sp. and Ancylostoma duodenale, for example. Learn more about the parasitological examination of feces.
How coproculture is done
In order to carry out co-culture, it is recommended that the person collect the feces, and the feces that have come into contact with the urine or the vessel should not be collected. In addition, if blood, mucus or other changes in the stool are seen, it is recommended that this part be collected, as there is a greater probability of identifying the microorganisms possibly responsible for the infection.
In some cases, it may be suggested by the doctor that the collection be made using a swab directly from the person's rectum, this collection being more frequently performed in people who are hospitalized. See more about stool examination.
After collection and adequate storage of the sample, it must be taken to the laboratory for analysis. In the laboratory, the feces are placed in specific culture media that allow the growth of invasive and toxigenic bacteria, which are those that are not part of the normal microbiota or that do but that produce toxins and lead to the appearance of gastrointestinal symptoms.
It is important for the person to indicate whether they are using any antibiotics or if they did it in the last 7 days before the test, as it may interfere with the result. In addition, it is not indicated that the person uses laxatives to stimulate bowel movement, as it can also interfere with the test result.
See more details on how to collect the stool for the exam in the following video: