The basic concept and the method or role of sterilization of common bacteria to kill all microbes (including pathogenic and non-pathogenic bacteria) and propagules and spores in objects.
Disinfecting and killing pathogenic bacteria. Medicines with disinfecting effect are called disinfectants, and they only have an effect on bacterial propagules at a commonly used concentration, but have no effect on spores.
Bacteriostatic method or effect to prevent or inhibit biological growth. Drugs used for bacteriostasis are called bacteriostatic agents or preservatives. Many drugs only have bacteriostatic effects at low concentrations. When the concentration increases or the action time is long, they can exhibit bactericidal effects. The bactericidal effects and bacteriostatic effects are collectively called antibacterial effects .
Microorganisms and their harmful microorganisms are a collective term for a group of small, simple, and low-level organisms. They generally include viruses, viroids, rickettsiae, bacteria, fungi, yeasts, nematodes, small algae, and protozoa. The microorganisms that are closely related to people's daily lives are bacteria and molds:
(1) Gram-stained bacteria are Gram-positive bacteria with Gram stains, and red ones are negative bacteria. According to the basic form of bacteria, it can be divided into cocci, bacillus and spiral bacteria. Common pathogenic bacteria are: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella, Streptococcus (2) Part of the fungus of the genus Mycobacterium, which grows on the culture medium into a pile-like or cotton-like hyphae And fungi that can cause mildew in the materials of various products. Common pathogenic molds are: Aspergillus flavus, Aspergillus nidulans, Penicillium tangerine, etc .; Common molds that pollute the environment are: Aspergillus niger, Aureobasidium pullulans, Paecilomyces variotii, and Trichoderma viride. (From "Industrial Fungicide")
The mechanism of action of antibacterial agents The appearance of poisoning by antibacterial agents on microorganisms mainly affects the growth of mycelium and spore germination. Formation of various fruiting bodies, cell permeability, mitosis, respiration and cell swelling, disintegration of cell protoplasts and damage to cell walls, etc. In essence, the physiological, biochemical reactions and metabolic activities of microbial cells are disturbed and destroyed, which ultimately leads to the inhibition of microbial growth and reproduction, and even death.
The effect of antibacterial agents on microorganisms is closely related to the concentration of the antibacterial agent and the length of the action time. Some are just to inhibit a certain process of the life activities of microorganisms because they are blocked, so there are sterilization and bacteriostasis. Antibacterial agents and antibacterial products contain dual functions of sterilization and bacteriostasis.
Antibacterial mechanisms can be generally divided into two categories: one is to destroy the structure of the bacteria, and the other is to affect the metabolism and physiological activities. The situation of destroying the structure of the bacteria can be divided into several types; 1) acting on the cell wall, such as: quaternary ammonium salts can adsorb negatively charged bacteria, causing damage to the cell wall structure and causing the contents to leak out. 2) Acting on the plasma membrane. Such as: toxic heavy metal ions, pyrimidines, imidazole antibacterial agents. 3) Action on cell contents. Such as: quinones, phenols, ketones, etc., involving a variety of organic antibacterial agents. In addition, inorganic heavy metals destroy the three-dimensional conformation of proteases by binding to the thiol group (-SH) of proteins, killing microorganisms.
The effects of metabolism and physiological activities can be divided into the following types: 1) Effects on enzyme systems, such as: 8-hydroxyquinolinone, heavy metal ions, formaldehyde, etc. 2) Inhibit respiration, such as: 2,4-dinitrophenol inhibits oxidative phosphorylation of microorganisms. 3) Influence on mitosis, such as Î±-naphthylamine and phenols.
The effect of an antibacterial agent on microorganisms is not single, it may act on several aspects at the same time, or it may act on one point to produce multiple effects. The specific mechanism of action of many antibacterial agents is not completely clear, but mastering the different mechanisms of action of antibacterial agents can better exert their effects.
Performance testing of antibacterial materials and their finished products The performance testing of antibacterial materials and their finished products is relatively complicated, and the methods are mainly divided into the following categories:
Cultivation method: The bacteria are dripped or spread on the sample and incubated for a period of time to elute. The live bacteria counting method calculates the antibacterial rate. This method requires strict control of nutrition, temperature, humidity, PH, time, etc. Specifically, there are two kinds of film sticking method and dipping method. The former is suitable for plastics (excluding foam products), paint, ceramics and other materials; the latter is suitable for antibacterial fabrics, foamed plastics, disposable hygiene products, etc. These two methods can be strictly quantified, and the antibacterial effect is represented by accurate data, which is a recognized method at home and abroad.
Contact method and Quinn method: The sample is directly placed on the culture medium mixed with the bacterial solution is called the contact method, and the sample is embedded in the medium is called the Quinn method. This method is used to observe the growth of bacteria on and around the sample and the erosion of the sample after incubation under certain conditions for different times. It is suitable for the detection of various materials, and it is also a commonly used method in the world, but it is used for product quality control. The evaluation cannot be expressed quantitatively, and there is a tendency to be eliminated in recent years.
Oscillation method: This method immerses the sample in a certain concentration of bacterial solution and continuously shakes the culture. The antibacterial rate is calculated by the live bacteria counting method at a certain time. This method is suitable for fabrics, foam materials, disposable hygiene products or small areas. Products can be obtained in a short time.
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