What Is A Stool Sample?
A stool sample is an effective method of identifying diseases of the digestive system associated with infections. It is even a common mechanism for conducting various scientific studies which conclude the presence of bacteria or parasites in the intestines.
We are often infected by parasites, viruses and bacteria, which create various symptoms in the intestines. Some disorders are also seen in the form of blood in the stool, such as colitis, colon cancer and stomach ulcers. A stool sample is therefore a mandatory examination.
Microbiological tests
A microbiological test is a method based on the multiplication of microorganisms, generally bacteria, in a sterile apparatus in order to facilitate the detection of a disease that causes disorder. In short, it is to provide microorganisms with the ideal environment for their development.
The patient’s biological samples come from saliva, saliva, parts of the skin and also feces. Scientists place them in a small container called a petri dish, with a solid substance inside that contains agar.
Many pathogens have specific growth requirements, so each device is specialized based on the microorganism being examined, as reported by this portal, which specializes in immunology. Some of these parameters are as follows:
- Availability of nutrients suitable for bacterial growth.
- Presence or absence of oxygen and other gases.
- Appropriate humidity.
- Ambient light.
- Acidity or alkalinity.
- Temperature.
- Environmental sterility.
Depending on the type of micro-organisms one wishes to find, the circumstances of the sample must be different. As soon as there is growth in the dish, experts isolate the samples under a microscope in order to identify the specific species that cause disease.
As various scientific sources point out, there are many different types of spots to identify a bacterium. Experts place a dye in the stain that the microorganism takes, making them that color. The most common is gram staining.
Petri dishes are where microorganisms grow in laboratories.
What is a stool sample?
A stool sample is nothing more than a microbiological sample based on a collection of stools as a sick patient’s sample. It is most of all used to study cases of persistent or recurrent diarrhea without a known cause.
As this medical article mentions, the collection of feces is necessary for infectious enteric disorders which do not subside within two or three days. Some of the pathogenic microorganisms that can be identified with a stool sample are Salmonella, Campylobacter, Helicobacter, Shigella, Yersinia, Clostridium difficile and also Staphylococcus auerus.
Collection of the sample
The article we quoted above mentions the steps one must take to collect the sample:
- The patient gives a sample in a container with an airtight lid with a minimum volume of two to four grams for solid stools and five to ten milliliters for liquid stools.
- Fecal samples that have been exposed to the environment for two hours or more, or that are contaminated with urine or toilet paper, are not valid.
- Scientists take a very small sample from the patient’s feces and place it on a device suitable for pathogenic microorganisms to grow there.
- If the first sample does not show the presence of enteropathogens, it is necessary to collect two more samples on different days.
- Once the pathogenic bacterium has been identified, the appropriate type of antibiotic is prescribed.
What to observe in a stool sample?
Scientists use these microbiological samples to identify various diseases through identifying bacteria by placing the stool sample and then analyzing it. They are also investigating possible eggs and remains of parasites.
According to the Center for Disease Control and Prevention (CDC) , parasites such as tapeworms have been identified in fecal samples since their eggs are seen in the feces of a patient. Likewise, if they do not detect hidden blood immediately in the stool, a biochemist can detect it.
Restrictions on stool samples
Not everything is ideal in microbiological tests. Results are not always possible and depend a lot on the quality of the sample. As this scientific article mentions, there are certain risks when identifying diseases through stool samples.
First , scientists cannot routinely search for all enteropathogens. Because the device is specific to each microorganism one wants to find, some less common ones such as Bacteroides fragilis, Edwarsiella tarda and Escherichia alberti may not grow.
There are also unknown pathogens whose biological requirements we do not know. They may therefore not want to reproduce as they do not have the right circumstances to do so. It is outside the current clinical situation where the goal is to look for common diseases.
Other studies argue that a stool sample is not appropriate for people who have been hospitalized for more than three days. This is because diarrhea is not caused by pathogens in the intestines. In this case, the most appropriate method is a PCR technique which identifies specific genes of a microorganism in the stool sample.
During hospitalizations, stool samples are limited in terms of use and effectiveness.
What to keep in mind regarding a stool sample?
These microbiological tests are useful in identifying pathogenic enteric bacteria, parasites and also blood in the stool. However, due to the high cost and delay in the procedure, only patients with specific epidemiological problems get them done.
However, if you need to do a stool test at the hospital, there is nothing to worry about. Doctors will try to identify the exact cause of gastrointestinal diseases so that they can prescribe the correct drug.
