What is a bacteriological study? By what scheme is it carried out? What is meant by safety in this case? What are the objectives and stages of bacteriological research?
general information
Bacteriological research is a scientific process in which bacteria are detected and their properties are studied with the aim of establishing a microbiological diagnosis. Of great importance here is the definition of the type or species of the microorganism obtained (a pure culture is implied). This is accompanied by a study of the biochemical and physiological properties of organisms, as well as the propensity to toxin formation. Precipitation and agglutination reactions are used for these purposes. Also, infection of laboratory animals with subsequent detection of pathological changes is practiced.
Work with the test material
The algorithm of bacteriological research provides for strict adherence to a special instruction. Thus, the material under investigation must be collected in sterile dishes under aseptic conditions. Also, care should be taken to ensure that delivery to the laboratory is carried out as soon as possible. It is desirable to store samples in the cold. The method of bacteriological research provides many possible situations. So, the type of object, the properties of the microorganism and the nature of the disease make it often necessary to develop individual instructions for work. A lot of different methods are used in the work. One of the most common is bacterioscopy. But if the bacteria are not fixed, then use a crushed or drooping drop. It should be noted that the last two options are distinguished by an increased level of infectiousness.
Bacterioscopy
In this case, smears are used. To create them, you need a drop of liquid, which is investigated, distributed over the surface of the slide. Sweating should dry it. This is often done by moving the drug through a flame obtained from a gas burner. Although fixing compounds may be used as an alternative. To indicate that preparatory actions have been carried out with this preparation, it is stained. The purpose of such manipulation is accuracy, which is very important when microscopic and bacteriological research is conducted. After all, if you re-use the drug for a different purpose, you will get a mess, it will be very difficult to work effectively with it.
Why is bacterioscopy so popular?
Last but not least, this is due to the availability of this method. If a bacteriological study of a fresh preparation is carried out, microchemical reactions or selective staining of various structural parts of the microorganism can be used to determine the pathogen. Which one is better? A more accurate result can be obtained when working with a colored preparation. In this case, the test material is applied to a pre-prepared glass. And necessarily thin (and if possible and even) layer. After this, you must wait until the drug dries in the air. The microorganisms are then fixed using one of the conventional methods. After this, the cooled preparation is dyed with a differential or simple paint. For this, dry and native preparations can be used. After that, it remains to direct ultraviolet or short blue rays to the place of congestion of organisms, which causes the entire microbe or some parts of its body to glow.
Practical use of bacterioscopy
It is used to diagnose a number of infectious diseases. The most famous of them are tuberculosis, gonorrhea and recurrent typhus. In addition, the study is used to study the entire complex of organ or product microflora. But critics often point to the relative unreliability and inaccuracy of this method.
Crops and cultures of bacterial cultures
They are carried out using a Pasteur pipette. Carrying out bacteriological and cytological studies is often difficult to implement without sowing and re-seeding during the work process. When the work is carried out with the Pasteur pipette, its tip breaks off with tweezers. The tool itself is then passed through the flame of the burner and then allowed to cool. By the way, when sowing, both liquid and solid nutrient media can be used. Influence on the choice is what the objectives of bacteriological research are pursued. In this case, it is necessary to adhere to the algorithm of work and safety. So, when working with a liquid nutrient medium, you need to make sure that it does not pour out and soak the edges of the plug and tubes. When research is conducted with solid material, a special needle is often used to introduce a culture. When crops are sown and re-planted, they must be carried out near the flame of the gas burner. For the purity of the experiment, the test tube should not remain open for long. About the instrument with the culture: you should make sure that it does not touch anything. Also, the technique of bacteriological research involves burning the edges of the tube before closing it. The finished product should be signed immediately after manufacture in order to avoid confusion in the future.
Efficiency of sowing
It is believed that this method makes it possible to obtain more accurate and reliable data during bacteriological diagnostics than the previously considered bacterioscopy. In this case, the algorithm of actions is as follows:
- Initially, the pure culture is spread over the surface of the nutrient medium, which is poured into a Petri dish.
- Initial seeding should be carried out under conditions that are favorable for this type of microorganism.
- After a day or two, in the presence of an optimal environment, all suitable colonies are moved to where they can develop to the maximum. This frees them, thus, from extraneous microflora.
The end result is a culture of homogeneous bacteria that can be identified.
Pure Crops
But how are they obtained? For this, biological and mechanical methods are used. In the first case, a large role is played by nutrient media, where there are necessary conditions favorable for the development of a certain culture. An approach can also be used when laboratory animals that are sensitive to a particular type of bacteria become infected. Mechanical methods are based on the use of a sterile instrument, through which the culture is placed in the nutrient medium found in the first, second and third petri dishes. Then it is necessary to wait until separate colonies grow, and from them a pure culture will already be allocated. Also, bacteria can be grown in special thermostats, where the temperature of a certain level is maintained (usually about 37 degrees). In this case, the process lasts about a day. But, depending on the type of microorganisms, other terms can be established. Also, it is important to have the necessary oxygen concentration. To do this, use different methods of aeration. So far, we have talked about the situation as a whole and in general, and now let's focus on what the scheme of bacteriological research is.
Practice
A set of methods is often used to identify pathogenic microorganisms in the body of a patient or potential carrier. The materials and methods used depend on the objectives pursued by the analysis, as well as on the environment in which the work is carried out. In practice, bacteria are most often detected through the sowing of blood taken from a person or an animal. If local lesions are well pronounced, pathogens can be found in problem areas. This is typical for such ailments as dysentery, gonorrhea, diphtheria, and a number of similar ones. In particularly severe cases, this process is divided into separate stages of bacteriological research (which is characteristic of typhoid fever). Each of them uses its own methods, which are aimed at finding the cause of infection. Let's take a more detailed look at the situation with typhoid fever. In the first week of the disease, the most reliable way to diagnose the disease is to sow blood. The second is serological examination. On the third week, examine the excrement. The last method is the verification of convalescents.
Identification of a microorganism
It begins with the process of its staining. Then watch how the bacteria can break down carbohydrates, amino acids and so on. In addition, this process can be supplemented by studying other properties that each individual genus or species of microorganisms possesses. As an example, the possibilities of dissolution of erythrocytes of various animals, the effect on clotting of blood plasma and the dissolution of a fibrin clot, and so on should be cited. All this is the differential features of individual representatives of the microworld. Serological identification may also be used for definitive recognition (but this usually refers to pathogenic bacteria that belong to the intestinal family).
Conclusion
It should be noted that a number of microorganisms can not be identified by the methods described in the article. In this case, the practice of infecting laboratory animals is widely used. The calculation is made that there will be a characteristic toxigenicity or pathogenicity, which is not observed in artificial conditions. Also, infection can be used as a method of accumulating pathogenic microbes. And already when the characteristics of the culture studied, found during the study of biological, morphological, serological and biochemical properties, are compared, it can be said that it is known what kind of microbes we are dealing with. Identification means the indication of the genus, species and type of bacteria. If the investigated microorganism deviates in certain properties from its typical characteristic, then it must be indicated. A number of specialists believe that in such cases it will be useful to conduct a re-identification with duplication of all the methods and techniques used. Sometimes research can be transferred to a new level, which implies a more serious approach (and more expensive). If negative results were obtained, this indicates that there were no microorganisms in the preparation or they were not viable. But for the accuracy of the studies, when suspicion of a number of bacilli carriers (dysentery, diphtheria, typhoid fever) in such cases, repeated tests are shown. This is necessary in order for specialists to have an accurate idea of what has to be dealt with.