- What is Helicobacter?
- Who is recommended to check the analysis of feces for Helicobacter pylori?
- Method of bacteriological culture
- Immunological methods of research
- PCR method
- How to evaluate the results of tests?
- How to prepare for the analysis?
- Additional Studies
- Related Videos
A positive result of the analysis of feces for Helicobacter serves as a reliable proof of human infection. The study relates to direct species when a particular causative agent or its DNA is detected, rather than the effects of its action or degradation products( as in carrying out immunological blood tests).
In addition, the advantage of the method is its non-invasiveness - no need to apply for collection of material more or less traumatic procedures( puncture the veins to take blood, insert a duodenal probe).
The analysis of stool is not related to the presence of the patient, enough timely delivery of feces to the laboratory. This is especially important for examining children.
There are different methods for identifying Helicobacter pylori, each has its own merits and demerits.
The attending physician determines the need and choice of the method of investigation. Of great importance is the availability of analysis for a particular patient because of the price. Most of it is performed only in private clinics and laboratories, because it requires expensive equipment.
The purpose of the study was to identify the causal relationship of the disease with Helicobacter and to prescribe a targeted course of treatment for getting rid of the pathogen.
What is helikobaktery?
The name Helicobacter pylori is translated as "spiral-shaped gatekeeper".It is tied to the characteristic form of the bacterium, localization in the area of the pylorus( border zone of the stomach with the duodenum).The microorganism has flagella, which helps it to move even in dense mucus.
Helicobacterium is able to withstand the acidic environment of gastric juice. For life support uses the energy of hydrogen molecules, which is produced by intestinal bacteria.
The bacterium synthesizes about 20 enzymes
The most known enzymes are Helicobacter:
Specific features of the microorganism include:
- the complexity of culture isolation, since Helicobacterium does not grow on normal nutrient media;
- a long period of absence of symptoms indicating infection;
- possibility in a "dangerous" situation to be transformed into a spherical shape and covered with a protective film.
In a feces the spiral form can not be detected, since the intestinal environment is unfavorable for the existence of Helicobacter. There is no necessary acidity, little oxygen, strong bile enzymes that destroy enzymes, pancreas. Therefore, in the fecal masses is the coccus form of the bacterium.
Who is recommended to check the analysis of feces for Helicobacter pylori?
Symptoms of stomach damage caused by Helicobacter pylori may be minimal or correspond to the clinic of exacerbation of the disease. The patient is observed:
- pain syndrome, especially with exacerbations in spring and autumn;
- constipation or diarrhea;
- feeling of heaviness in epigastrium;
- decreased appetite;
- sharp drop in weight.
The indications for the study can be:
- need to check before a long course of therapy with nonsteroidal anti-inflammatory drugs, proton pump inhibitors, as they reduce the production of hydrochloric acid in the stomach;
- signs of iron deficiency anemia;
- not clear thrombocytopenia;
- possibility of infection of family members;
- control of the course of antibiotic therapy;
- finding out the connection with the genetic predisposition.
The child's symptoms of infection are complaints of nausea, vague abdominal pain, poor appetite and refusal to eat, frequent profuse regurgitation, and bloating and rumbling of the abdomen.
Method of bacteriological culture
Isolation of culture of the pathogen is a microbiological study. The classics of the method require the sowing of the material on the nutrient medium, the counting of the grown up colonies, the study of the microorganism from the colony under a microscope. It is also necessary to conduct biochemical tests to study its properties and additional seeding on a medium with antibiotics to detect sensitivity to different drugs.
Medium for sowing is quite expensive, specially prepared
Caliber analysis for Helicobacter pylori with the help of the culture method is difficult:
- sowing must be done without access of oxygen;
- can distinguish only spiral forms that rarely enter the feces, but not coccal;
- , the results of the response to antibiotic sensitivity in vitro( in vitro means "on glass, in vitro") in practice are deceptive and in some cases do not coincide with actual use in a patient( in vivo), the optimal antibiotic found is not effective enough;
- analysis requires a long time( 7-10 days) for complete implementation.
Immunological research methods
The essence of the immunological assay is the detection of antibody + antigen complexes in which the foreign agent is Helicobacterium. More common use of the study of blood. But in fact, indirect evidence of the presence of antigen can be confirmed by the presence in the stool, saliva, urine, in pregnant women in the amniotic fluid.
The methods use ready-made "tagged" antibodies. When treating the stool of a patient containing antigens( residues of Helicobacter pylori), a reaction of the compound with standard antibodies occurs. The duration of the study is 24 hours. Analysis of feces for Helicobacter antigen is prescribed if the patient has any symptoms of digestive disorders.
The most common variant is the primary screening of the population( examination of all the applicants or certain groups) that does not have specific complaints. In Russia it is not used because there are not enough immunological tests in the laboratories of polyclinics.
Polymerase chain reaction( PCR) refers to molecular genetic diagnosis. With its help, not a bacterium, but its specific DNA is revealed. Even with a small amount, in the case of convalescence or asymptomatic carriage, the method makes it possible to relate, with sufficient accuracy, changes in the body to Helicobacter action.
Duration of analysis by express method 5-6 hours, usual - 2-3 days
The method is designed for artificial synthesis of separate parts of DNA, doubling and building a chain of 30 cycles. The process does not occur in the absence of the slightest remains of the biomaterial. For the reaction, an ampli fi er is necessary. Polymerase is an enzyme that accelerates the process.
PCR feces are prescribed to confirm the role of helicobacteria in pathology and to determine the appropriateness of specific therapy:
- with erosions and ulcers in the stomach, esophagus and duodenum;
- gastroesophageal reflux( throwing content in the opposite direction);
- atrophic lesion of the gastric mucosa;
- stomach tumors;
- revealing hereditary predisposition in the case of relatives of malignant tumors of the digestive system;
- monitoring the results of antibiotic therapy.
The advantages of PCR feces can be considered:
- high sensitivity and specificity( respectively determined in 94% and 100%), the reaction is positive even with 10 bacteria;
- simplicity of holding;
- safety for the patient, no traumatism when taking material;
- the ability to determine DNA in both helical and coccal forms of Helicobacter pylori;
- isolation and study of various genetic modifications, strains.
Disadvantages of the study:
- does not appear to be the ability to determine the optimal antibiotic for sensitivity;
- there is no difference between the acute acute disease and the residual events after exacerbation, bacterial DNA remains in the stool almost a month after clinical recovery;
- sensitivity is still lower than when examining a biopsy from the stomach wall;
- comparatively high cost;
- need to train staff and purchase equipment;
- is a positive reaction in cases of contamination by a person of material from a foreign sample( contamination from outside).
The PCR laboratory has an improved technique to obtain reliable diagnostic results of the
. How to evaluate the results of the tests?
Explanation of the results of the study is a matter of a specialist doctor. Do not resort to self-interpretation or use the services of friends. The evaluation is conducted on a set of characteristics. When PCR results:
- negative, if the genotype of Helicobacterium has not been isolated, it is found out normal;
- is positive if the patient has had a history of illness or a history of infection.
At bacteriological research:
- the zero quantity of bacteria is found out or helikobakter is absent;
- if the number of microorganisms is greater than zero - helibacteriosis is confirmed;
- S indicates sensitivity to the claimed antibiotic;
- R - indicates resistance( resistance) to the drug;
- I - the sensitivity is moderate.
Bakposov kala allows to give not only qualitative, but also quantitative characteristics of helicobacterial infection. For this, the bacterial growth rates are taken into account:
- 1 degree - there is a slight growth in the liquid medium, on solid samples - there is no growth;
- 2nd degree - grows up to 10 colonies;
- 3 degree - the number of colonies that have grown reaches 100;
- 4 degree - the prevalence and activity of the pathogen are very active, grows more than 100 colonies.
Test is performed by enzyme immunoassay with standard sera
Immunological tests show negative results if the pathogen antigen is not detected, positive - in the presence of helicobacteriosis. The reliability of immunological and cultural methods is much inferior to PCR, for their conduct a massive prevalence of the pathogen in the feces is needed.
How do I prepare for the test?
Where it is possible to pass the analysis, the doctor will specify. He also needs to familiarize the patient with the rules of material intake and preparation. Some private clinics give visitors a printed instruction "How to take tests."The effectiveness of the research depends on the observance of these conditions.
The general rules for the collection of feces for the detection of Helicobacter are:
- discontinuation of antibacterial agents three days before the analysis;
- a control test for feces is carried out a month after the end of the course of treatment;
- some tests require three days before the study to go on a diet without foods with dietary fiber, exclude pickles, alcoholic beverages;
- prohibition on the use of laxatives, rectal suppositories, if treatment requires a daily intake, the doctor should be warned;
- to collect the feces needed in clean laboratory utensils( issued in the clinic or bought at the pharmacy), it is desirable to take samples from three points;
- unsuitable is considered feces with impurities of mucus, pus, blood, urine;
- delivery of material to the laboratory should be provided in the first 2 hours, if necessary, it is allowed to store in the refrigerator for no more than 24 hours at a temperature of 2 to 8 degrees.
Special kit for stool collection for analysis can be purchased at the
pharmacy. Additional investigations
The patient should not insist on an isolated stool examination when performing the diagnosis. Using additional types, the doctor raises the reliability of information on infection with Helicobacter pylori.
Urease respiratory tests are very popular.
An incontrovertible type of examination is a cytological examination of a sample of the gastric mucosa obtained by biopsy during fibroadastroscopic examination. At a high resolution of the microscope, the lab technician sees the stained Helicobacter pylori.
Fibrogastroscopic picture of the mucosa itself with characteristic erosions, atrophy, ulceration indicates indirect signs of the presence of an agent in the stomach. Radiographic diagnosis also allows for violations in the direction of folds, contours of the stomach to judge the organic pathology caused by Helicobacter pylori.
Based on the results of the tests, a doctor can introduce a patient into a risk group with an increased likelihood of a stomach ulcer, malignant tumors. Preliminary application of specific treatment allows to reduce the degree of risk. When choosing a medical institution to perform research on paid terms, you need to consult about the reputation and responsibility of its employees.