New Technology in Bacteriological Diagnostics (I)

with the continuous development of modern science and technology, especially immunology,
biochemistry
and molecular biology, new bacterial diagnostic techniques and methods have been widely used in the identification of food
microbial
. Traditional bacterial isolation,
culture
and bio-chemical reactions are far from sufficient for the diagnosis of various pathogenic microorganisms and epidemiological studies. In recent years, scholars at home and abroad have made continuous efforts to create a number of fast, simple, specific, sensitive, low-consumption and applicable bacteriological diagnostic methods, especially DNA probes and polyenzyme chain reaction technology development and application, significantly improve the level of bacterial diagnosis.
I. Rapid enzyme contact reaction and detection of bacterial metabolites
rapid enzyme contact reaction is based on the bacteria in its growth and reproduction process can synthesize and release certain specific enzymes, according to the characteristics of the enzyme, select the corresponding substrates and indicators, they are prepared in the relevant medium. Based on the obvious color changes that occur after the bacterial reaction, the suspect strain to be isolated is determined, and the results of the reaction are helpful for the rapid diagnosis of the bacteria. This technology combines traditional bacterial separation with bio-chemical reaction, and makes the test results intuitive, which is becoming a major development direction of microbial detection in the future. Rosa and others inoculated the samples directly into the Granda culture, and after 18 hours of culture, group B streptococcus developed red bacteria and inhibited the growth of other bacteria.
Delise and other newly synthesized hydroxypyridine-β-D glucoglycic acid (IBDG), under the role of β-D glucosidease, the production of insoluble blue, will be a certain amount of IB DG was added to the McCongay medium
gaglue
to make a MAC-IBDG tablet, cultured for 18 hours at 35 degrees C, and the dark blue colony was found to be a positive strain of E. coli. Its color is unique, and indigo is not easy to spread, easy to distinguish from lactose fermentation strains.
2. The technology of immunological methods to detect bacteria
antigens
or
antibodies

has received increasing attention in the diagnosis of bacteria using various methods of immunology, thus simplifying the identification of pathogenic microorganisms.
1.
Serum
Coagulation Technology
As early as 1933, Lancefield successfully serotonysis streptococcus with polypicilmic serum. With the further improvement of anti-institutional preparation technology, especially the preparation of monoclonal antibodies, the specificity of bacterial coagulation experiments has been significantly improved, and today it is widely used in the segmentation and identification of bacteria, such as salmonella, Vibrio cholerae and so on.
2. The latex gel set experiment
wraps specific antibodies on latex particles and binds the antibodies to the corresponding bacterial antigens to produce a coagulation reaction visible to the naked eye. Usually this method requires the obtaining of a bacterial pure culture, and then the culture and allergenic latex reaction. Has been used to identify E. coli O157; H7
3. Fluorescent antibody detection
fluorescent antibody technology for rapid detection of bacteria is mainly direct and indirect. The direct method is to directly drop an anti-serum with known specific fluorescence markers on the test sample and, after washing, observe the results under a fluorescent
microscope
a microscope. Indirect method is to add known bacterial-specific antibodies to the sample, after the action after washing, and then add a fluorescent marker of the second antibody. Such as the development of anti-salmonella fluorescent antibodies for the detection of 750 food samples, the results show that the compliance rate with conventional culture method is basically the same.
4. The Coagulation Test (COA)
has been shown to have the ability to bind to the Fc segment of IgG in humans and various mammals without affecting the activity of the antibody Fab segment. In recent years, domestic and foreign scholars have used antibody-sensitive SPA to detect bacteria, i.e. coagulation tests. Such as Rahman and other collaborative coagulation test to identify the first-generation isolates of Vibrio cholerae O1 group to do rapid screening, saving time than conventional methods, 204 materials with two methods to compare show that the collaborative coagulation test has a high specificity and sensitivity.
5. The application of enzyme-linked immuno-testing technology
-enzyme-linked immune technology has greatly improved the sensitivity and specificity of detection and has been widely used in the testing of pathogenic microorganisms.the mini-Vidas fully automatic immunoanalyst, manufactured by
using enzymatic immune technology, is a solid-phase adsorbent using fluorescence analysis technology, using known antibodies to capture the target organism, and then re-binding with fluorescent enzymatic antibodies, which are fully flushed and detected by exciting light sources, i.e. Automatic reading of positive specimens of starting light, the advantages of which are high sensitivity, fast detection, can quickly identify salmonella, E. coli O157:H7, monocyclist bacteria, keratobacteria and staphylococcus enterotoxin in 48 hours.