To conduct a tank study, a swab from the pharynx and nose is required. It allows you to assess the qualitative as well as quantitative characteristics of the microflora living on the mucous membrane of the oral and nasopharynx. Having identified pathogenic microorganisms during diagnosis, the doctor has the opportunity to confirm an infectious disease, as well as to determine the sensitivity of microbes to the action of certain antibiotics.
Among the indications when an analysis is prescribed from the pharynx to the microflora, it is worth highlighting:
- tonsillitis due to streptococcus activation;
- furunculosis, which develops as a result of the multiplication of staphylococci;
- suspicion of diphtheria, when it is necessary to identify Leffler's bacilli;
- the presence of symptoms that indicate a meningococcal or pertussis infection;
- colds;
- suspicion of stenosing laryngitis or mononucleosis.
In addition, diagnostics is carried out with a preventive purpose to identify people with bacterial carriers after contact with a sick person, when employed in children's, medical institutions, catering establishments, before visiting educational institutions. Often a swab from the throat and nose is prescribed for staphylococcus aureus.
Also, pregnant women are examined to determine the risk of developing the disease and serious consequences.
Microflora of the nasopharynx
Many microbes live on the surface of the mucous membrane of the mouth and nasopharynx, which are both useful and pathogenic microbes. Normally, even pathogens can be part of the flora, but not cause the development of the disease. It all depends on their number.
Under certain conditions, for example, a decrease in immunity against the background of acute respiratory viral infections, general hypothermia, exacerbation of chronic pathology, pathogenic bacteria are activated, and they begin to multiply intensively.
In the absence of disease, smears contain such types of microorganisms as Escherichia coli, streptococci, meningococci, epidermal staphylococcus, non-pathogenic neisseria, bacteria, diphtheroids, pseudomonas, Klebsiella pneumoniae, actinomycetes, fungi and other microorganisms.
Approximately 20% of the world's population are carriers of Staphylococcus aureus, but they do not develop the disease.
Under favorable conditions for bacteria, opportunistic microbes can cause disease. Also, diseases can develop during the primary infection of the body, settling on the mucous membranes of the upper respiratory tract.
Among the microorganisms that can provoke the development of pathology, hemolytic streptococcus, pneumo-, meningococcus, Staphylococcus aureus, Leffler's bacilli, Haemophilus influenzae, Branchamella, Listeria, Bordetella, fungi and many other microbes should be noted.
Preparatory stage
To obtain the most accurate research results, the following recommendations must be observed:
- a week before collecting the material, the intake of antibacterial drugs is stopped;
- rinsing, the use of an antimicrobial spray is prohibited 2 days before the diagnosis;
- the analysis is carried out on an empty stomach;
- before the examination, you should not brush your teeth, use chewing gum, drink water.
Only by adhering to the listed rules, a smear on the flora from the pharynx will show a reliable result.
Technique
To make taking a swab from the throat somewhat easier, it is necessary for the patient to tilt his head back and open the oral cavity as wide as possible. Material from the nose and throat is taken with a sterile swab fixed on an elongated loop.
First, the specialist presses the tongue with a metal or wooden spatula to the bottom of the oral cavity in order to clearly visualize the site of material sampling. Then the swab is lowered into a sterile tube, which prevents the death of microorganisms during transportation. The material should be taken to the laboratory within 90 minutes.
During the insertion and removal of the tampon from the mouth, it should not come into contact with other surfaces. If the technique for taking a throat and nasal swab is not followed, the results are considered unreliable.
It is worth noting that the process of taking the material does not cause pain, but it provokes an emetic urge, especially in people with an increased gag reflex.
The algorithm for performing a nasal smear is practically the same:
- the patient tilts his head back;
- the nasal passage on both sides is cleared of mucus;
- the skin around the nostrils must be treated with an antiseptic;
- a sterile swab is inserted into the nasal passages, tightly in contact with the surface of the mucous membrane;
- the swab is placed in a sterile tube and sent to the laboratory.
Microscopic analysis
Before sowing the material, it is necessary to conduct a microscopic examination. For this, the collected material is placed on a glass slide, which is fixed over the burner flame. Staining is carried out according to the Gram method, which makes it possible to visualize the cellular composition.
In smears, coccobacilli, gram-positive, gram-negative microbes and cocci can be found, and their morphology is also examined. Depending on the location of bacteria, it is possible to distinguish them by species:
- gram-positive cocci, arranged in groups in the form of a bunch of grapes, are staphylococci;
- gram-positive cocci, resembling a chain, or arranged in pairs, are considered streptococci;
- Neisseria are negatively stained according to Gram, are also cocci;
- Klebsiella are visualized in the form of gram-negative rods with rounded ends, as well as a capsule with a light color;
- Pseudomonas aeruginosa appears as small gram-negative bacilli.
Based on the results of microscopic diagnostics, the doctor manages to guess which colonies can grow on the nutrient medium.
Sowing material
Each microorganism requires specific nutrient media, taking into account pH and moisture levels. The main task of the nutrient medium is to provide microorganisms with nutrition, respiration for growth acceleration and reproduction.
Sowing is carried out in a sterile box, observing the rules of asepsis. A specialist working in a laboratory must remember about protective equipment, since biological material can be infectious.
A nasal swab is sown onto the medium, after which it is grown in a thermostat. The growth and shape of the growing colonies must be assessed on a daily basis. After 5 days, the final result is analyzed. There are several common media for obtaining bacterial colonies:
- blood agar belongs to a highly sensitive type of media, provides favorable conditions for the growth of saprophytic and pathogenic microbes. The pathogenicity of pneumococcus, as well as staphylococcus, is assessed by analyzing the nature of growth, color and area of the hemolyzed area. The hemolytic activity of bacteria is considered the main pathogenic factor.
- Sabouraud's environment is optimal for the reproduction of many types of microbes.
- Yolk Salt Agar is used to obtain colonies of staphylococcal microbes.
- Chocolate agar is a non-selective, enriched medium obtained by adding heated blood. It is used for the reproduction of pathogenic microorganisms. This nutrient medium is well suited for meningococci, conococci and Haemophilus influenzae.
- Of the media for enterobacteria, the Endo medium is used.
- Cultivation of enterococci is carried out on enterococcal.
Diagnostic results
After evaluating the shape, color and other features of bacterial colonies, the specialist provides the final result:
- negative - means the absence of bacterial and fungal flora in the material. In this case, the cause of the development of the disease can be a viral pathogen.
- positive - indicates the presence of pathogenic / opportunistic microbes that can cause the disease. Activation and rapid multiplication of opportunistic microbes occurs with a decrease in immunity. In the presence of fungal flora, in particular the yeast-like fungi Candida, oral candidiasis can develop.
The doctor directs the patient to take swabs from the pharynx and nasal cavities if an infectious origin of the disease is suspected. Thanks to comprehensive diagnostics, the doctor is able to determine the composition of the microflora of the mucous membrane. This allows you to make an accurate diagnosis and determine further treatment tactics.
