Pathogenic microorganisms are microorganisms that can invade the human body, cause infections and even infectious diseases, or pathogens. Among pathogens, bacteria and viruses are the most harmful.

Infection is one of the main causes of human morbidity and death. In the early 20th century, the discovery of antimicrobial drugs changed modern medicine, giving humans a “weapon” to fight infections, and also making surgery, organ transplantation, and cancer treatment possible. However, there are many types of pathogens that cause infectious diseases, including viruses, bacteria, fungi and other microorganisms. In order to improve the diagnosis and treatment of various diseases, and to protect people’s health

Health requires more accurate and rapid clinical testing techniques. So what are the microbiological detection technologies?

01 Traditional detection method

In the process of traditional detection of pathogenic microorganisms, most of them need to be stained, cultured, and biological identification is carried out on this basis, so that different types of microorganisms can be identified, and the detection value is high. Traditional detection methods mainly include smear microscopy, separation culture and biochemical reaction, and tissue cell culture.

1 Smear microscopy

Pathogenic microorganisms are small in size and most are colorless and translucent. After staining them, they can be used to observe their size, shape, arrangement, etc. with the help of a microscope. The direct smear staining microscopic examination is simple and fast, and it is still applicable to those pathogenic microbial infections with special forms, such as gonococcal infection, Mycobacterium tuberculosis, spirochetal infection, etc. for the early preliminary diagnosis. The method of direct photomicroscopic examination is faster, and can be used for visual inspection of pathogens with special forms. It does not require special instruments and equipment. It is still a very important means of pathogenic microorganism detection in basic laboratories.

2 Separation culture and biochemical reaction

Separation culture is mainly used when there are many kinds of bacteria and one of them needs to be separated. It is mostly used in sputum, feces, blood, body fluids, etc. Because the bacteria grow and multiply for a long time, this test method requires a certain amount of time. , And can’t be processed in batches, so the medical field has continued to conduct research on this, using automated training and identification equipment to improve the traditional training methods and improve the accuracy of detection.

3 Tissue cell culture

Tissue cells mainly include chlamydia, viruses, and rickettsiae. Since the types of tissue cells in different pathogens are different, after the tissues are removed from the pathogenic microorganisms, the living cells must be cultured by subculture. Cultivated pathogenic microorganisms are inoculated into tissue cells for cultivation to reduce cell pathological changes as much as possible. In addition, in the process of culturing tissue cells, pathogenic microorganisms can be directly inoculated in sensitive animals, and then the characteristics of pathogens can be tested according to the changes in the tissues and organs of the animals.

02  Genetic testing technology

With the continuous improvement of the level of medical technology in the world, the development and progress of molecular biological detection technology, which can effectively identify pathogenic microorganisms, can also improve the current status of the application of external morphological and physiological characteristics in the traditional detection process, and can use unique genes The fragment sequence identifies the types of pathogenic microorganisms, so genetic testing technology is widely used in the field of clinical medical testing with its own unique advantages.

1 Polymerase chain reaction (PCR)

Polymerase chain reaction (Polymerase Chain Reaction, PCR) is a technique that uses known oligonucleotide primers to guide and amplify a small amount of the gene fragment to be tested in an unknown fragment in vitro. Because PCR can amplify the gene to be tested, it is especially suitable for the early diagnosis of pathogen infection, but if the primers are not specific, it may cause false positives. PCR technology has developed rapidly in the past 20 years, and its reliability has gradually improved from gene amplification to gene cloning and transformation and genetic analysis. This method is also the main detection method for the new coronavirus in this epidemic.

Foregene has developed RT-PCR kit based on Direct PCR technology, for the detection of normal 2 genes, 3 genes, and variants from UK, Brazil, South Africa, and India, the B.1.1.7 lineage (UK), B.1.351 lineage (ZA), B.1.617 lineage (IND) and P.1 lineage (BR), respectively.

2 Gene chip technology

Gene chip technology refers to the use of microarray technology to attach high-density DNA fragments to solid surfaces such as membranes and glass sheets in a certain order or arrangement through high-speed robotics or in-situ synthesis. With DNA probes labeled with isotopes or fluorescence, and with the help of the principle of base complementary hybridization, a large number of research techniques such as gene expression and monitoring have been carried out. The application of gene chip technology to the diagnosis of pathogenic microorganisms can significantly shorten the diagnosis time. At the same time, it can also detect whether the pathogen has drug resistance, which drugs are resistant to, and which drugs are sensitive to, so as to provide references for clinical medication. However, the production cost of this technology is relatively high, and the sensitivity of chip detection needs to be improved. Therefore, this technology is still used in laboratory research and has not been widely used in clinical practice.

3 Nucleic acid hybridization technology

Nucleic acid hybridization is a process in which single strands of nucleotides with complementary sequences in pathogenic microorganisms fuse in cells to form heteroduplexes. The factor leading to hybridization is the chemical reaction between nucleic acid and probes to identify pathogenic microorganisms. At present, the nucleic acid recrossing techniques used to detect pathogenic microorganisms mainly include nucleic acid in situ hybridization and membrane blot hybridization. Nucleic acid in situ hybridization refers to the hybridization of nucleic acids in pathogen cells with labeled probes. Membrane blot hybridization means that after the experimenter separates the nucleic acid of the pathogen cell, it is purified and combined with a solid support, and then hybridized with the accounting probe. The accounting hybridization technology has the advantages of convenient and fast operation, and is suitable for sensitive and purposeful pathogenic microorganisms.

03 Serological testing

Serological testing can quickly identify pathogenic microorganisms. The basic principle of serological testing technology is to detect pathogens through known pathogen antigens and antibodies. Compared with traditional cell separation and culture, the operating steps of serological testing are simple. Commonly used detection methods include latex agglutination test and enzyme-linked immunoassay technology. The application of enzyme-linked immunoassay technology can greatly improve the sensitivity and specificity of serological testing. It can not only detect the antigen in the test sample, but also detect the antibody component.

In September 2020, the Infectious Diseases Society of America (IDSA) issued guidelines for serological testing for the diagnosis of COVID-19.

04 Immunological testing

Immunological detection is also called immunomagnetic bead separation technology. This technology can separate pathogenic and non-pathogenic bacteria in pathogens. The basic principle is: the use of magnetic bead microspheres to separate the single antigen or multiple types of specific pathogens. The antigens are assembled together, and the pathogenic bacteria are separated from the pathogens through the reaction of the antigen body and the external magnetic field.

Pathogen detection hotspots-respiratory pathogen detection

Foregene’s  “15 respiratory system pathogenic bacteria detection kit” is under development. The kit can detect 15 kinds of pathogenic bacteria in sputum without the need to purify the nucleic acid in sputum. In terms of efficiency, it shortens the original 3 to 5 days to 1.5 hours.