What is a bacteriological study? According to what scheme is it carried out? What is meant by safety in this case? What are the goals and stages of bacteriological research?
general information
Bacteriological research is a scientific process in which bacteria are detected and their properties are studied in order to make a microbiological diagnosis. Of great importance here is the determination of the type or species of the resulting microorganism (pure culture is meant). This is accompanied by a study of the biochemical and physiological properties of organisms, as well as a tendency to toxin formation.
Precipitation and agglutination
reactions are used for these purposes. Also, infection of laboratory animals with the subsequent identification of pathological changes is practiced.
Work with the studied material
The bacteriological research algorithm provides for strict observance of special instructions. So, the test material must be collected in sterile dishes under aseptic conditions. It is also necessary to ensure that delivery to the laboratory is carried out as soon as possible. It is desirable to store samples in the cold. The methodology of bacteriological research provides many possible situations. So, the type of object, the properties of the microorganism and the nature of the disease often make it necessary to develop individual instructions for work. The work uses a large number of different methods. One of the most common is bacterioscopy. But if the bacteria are unfixed, then use a crushed or hanging drop. It should be noted that the last two options are characterized by an increased level of infectivity.
Bacterioscopy
In this case, smears are used. To create them, you need to distribute a drop of liquid, which is being investigated, on the surface of a glass slide. Zatas should dry it. For this, the movement of the drug through the flame obtained from a gas burner is often used. Although, alternatively, fixative formulations may be used. To indicate that preparatory steps have been taken with this drug, it is stained. The purpose of such a manipulation is accuracy, which is very important when microscopic and bacteriological studies are performed. After all, if you reuse the drug for another purpose, you get porridge, it will be very difficult to work with it effectively.
Why bacterioscopy is so popular
Not least of all, this is due to the availability of this method. If a bacteriological study of a fresh preparation is carried out, then 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 previously prepared glass slide. And always a thin (and if possible even) layer. After this, you must wait until the drug dries in air. Then microorganisms are fixed using one of the generally accepted methods. After that, the cooled preparation is subjected to staining with differential or simple paint. For this, dry and native preparations can be used. After this, it remains to direct ultraviolet or short blue rays to the place of the accumulation of organisms, which causes the glow of the entire microbe or individual parts of its body.
The practical application of bacterioscopy
It is used to diagnose a number of infectious diseases. The most famous of them are tuberculosis, gonorrhea and relapsing fever. In addition, they resort to research to study the whole complex of microflora of an organ or product. But critics often point to the relative unreliability and inaccuracy of this method.
Sowing and reseeding of bacterial cultures
Carry them using a Pasteur pipette. Bacteriological and
cytological studies are often difficult to carry out without seeding and reseeding during the work process. When working with a Pasteur pipette, its tip breaks off with tweezers. The tool itself is then carried 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
. The choice effect is what bacteriological research goals are pursued. In this case, it is necessary to adhere to the operating algorithm and safety precautions. So, when working with a liquid nutrient medium, it is necessary to ensure that it does not spill out and does not wet the edges of the cork and test tubes. When research is carried out with solid material, a special needle is often used to introduce culture. When sowing and reseeding, they should be carried out near the flame of a gas burner. For the purity of the experiment, the tube should not remain open for long. As for the instrument with the culture: it should be ensured that it does not touch anything. Also, the bacteriological research technique involves burning the edges of the tube before closing it. The finished product should be signed immediately after manufacture to avoid confusion in the future.
Sowing efficiency
It is believed that this method allows you to obtain more accurate and reliable data during bacteriological diagnostics than previously considered bacterioscopy. In this case, the algorithm of actions is as follows:
- Initially, a pure culture is spread on the surface of the nutrient medium, which is poured into a Petri dish.
- The initial sowing must 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 resettled 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 do they come about? For this, biological and mechanical methods are used. In the first case, nutrient media play an important role, 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 specific type of bacteria become infected. Mechanical methods are based on the use of a sterile instrument, with which the culture is placed in a nutrient medium located in the first, second and third Petri dishes. Then you need to wait until individual colonies grow, and pure culture will stand out from them. Bacteria can also be grown in special thermostats, where the temperature is maintained at a certain level (usually around 37 degrees). In this case, the process lasts about a day. But, depending on the type of microorganisms, other terms can be established. Also important is the presence of the necessary oxygen concentration. To do this, use various methods of aeration. So far, we have talked about the situation as a whole and in general, and now let's focus on what constitutes a bacteriological research scheme.
Practice
A set of methods is often used to identify
pathogens in the body of a patient or potential carrier. The materials and methods used depend on what goals the analysis pursues, as well as on the environmental conditions in which the work is conducted. In practice, most often bacteria are detected through the sowing of blood taken from a person or animal. If local lesions are well defined, pathogens can be sought in problem areas. This is characteristic of such ailments as dysentery, gonorrhea, diphtheria, and a number of the like. In especially severe cases, this process is divided into separate stages of bacteriological research (which is typical for typhoid fever). Each of them uses its own methods, which are aimed at finding the cause of infection. Let's take a closer look at typhoid fever. In the first week of the disease, the most reliable way to diagnose the disease is blood culture. The second is considered a
serological study. In the third week, feces are examined. The last method is checking for convalescents.
Microorganism identification
It begins with the process of staining it. Then they look at how a bacterium can break down carbohydrates, amino acids, and so on. Additionally, this process can be supplemented by the study of other properties that each individual genus or type of microorganism possesses. As an example, the possibility of dissolving the red blood cells of various animals, the effect on the coagulability of blood plasma and the dissolution of a clot of fibrin, and so on. All these are differential signs of individual representatives of the microworld. Also, serological identification can be used for final recognition (but this usually applies to pathogenic bacteria that belong to the intestinal family).
Conclusion
It should be noted that a number of microorganisms cannot be identified by the methods described in the article. In this case, the practice of infection of laboratory animals is widely used. The calculation is made on the fact that characteristic toxigenicity or pathogenicity is manifested, which is not observed in artificial conditions. Also, infection can be used as a method of accumulation of pathogenic microbes. And even when the characteristics of the studied culture, found in the process of studying the biological, morphological, serological and biochemical properties, are compared, we can say that it is known what kind of microbes we are dealing with. By identification is meant an indication of the genus, species and type of bacteria. If the studied microorganism deviates in certain properties from its typical characteristics, then this should be indicated. A number of experts believe that in such cases, re-identification with duplication of all the methods and techniques used will be useful. Sometimes research can be carried to a new level, which implies a more serious approach (and more expensive). If negative results were obtained, then this indicates that microorganisms were absent in the preparation or they were not viable. But for the accuracy of studies with suspected a number of bacillicarriers (dysentery, diphtheria,
typhoid fever) in such cases, repeated checks are shown. This is necessary so that specialists have an accurate idea of what they have to deal with.