Overview of disinfection and sterilization

sterilization and sterilization have different meanings. Disinfection generally refers to the elimination of pathogens and harmful
microbial
nutrients, sterilization refers to the elimination of all microorganisms nutrients, spores and spores. There are many methods of disinfection and sterilization, which can generally be divided into
heating
,

filtration, irradiation and the use of chemicals., heating method
and divided into dry heat sterilization and wet heat sterilization two categories.1. Dry heat sterilization
two types of flameburn sterilization and hot air sterilization. Flame burning sterilization is suitable for inoculation rings, inoculation needles and metal appliances such as tweezers, aseptic operation of the test tube mouth and bottle mouth also for a short period of burning on the flame sterilization. It is commonly referred to as dry thermal sterilization is sterilization in an electric oven, which is applicable to the sterilization of glassware such as straws and
cultured
dishes, etc., and is sterilized for 2 hours at 160-170 degrees C in hot air.2. Wet and thermal sterilization
(1) auto-steam sterilization method
This method is to place the item in a high-pressure steam sterilization pot 1.05 kg/cm2 (15 lb/inch 2), 121.3 degrees C to maintain 15-30 minutes for sterilization. The length of time can vary depending on the type and quantity of sterilized items, whichever is achieved. This sterilization is suitable
sterilization of
, work clothes, rubber items, etc.(2) Intermittent sterilization method
A small number of cultures such as gelatin culture, cow's milk culture, sugary culture, etc. with dry heat sterilization and autobaric steam sterilization will be destroyed, you must use intermittent sterilization method. This method is sterilized using the Anox mobile steam sterilizer (Figure VI.-1). The bottom of the device is full of water, the top is inserted with
thermometer
, after heating the water vapor temperature reaches 100 degrees C, that is, the circulation flow in the device, water vapor hit the object inside the device, and then condensed into water, flow to the bottom storage place, so it does not dry up. When sterilization, the medium is placed in the device, heated 100 degrees C for 30 minutes, three consecutive days, the first day after heating, the nutrients are killed, the medium will be removed at room temperature for 18-24 hours, so that the spores develop into nutrients, the second day reheated 100 degrees C 30 minutes, the developing nutrients are killed, but may still have spores, so that the completely sterilized. Generally, all items that can be sterilized with high-pressure steam are not sterilized by this method.(3) boiling disinfection method
syringes and anatomical devices can be used boiling disinfection method. General
biology
laboratory boiling disinfection time of 10-15 minutes, human syringes and surgical instruments in place, generally using auto-steam sterilization or dry heat sterilization.2. Filtration sterilization
Many materials such as
sery
and sugar solutions used in general heating disinfection sterilization methods, will be destroyed by heat, therefore, the use of filtration sterilization methods. The most widely used filters are Seitz filters and membrane filters. Cai's filter is made of silver or aluminum and other metals, divided into the upper and lower two sections, filtration, with a spiral to clamp the asbestos plate tightly between the upper and lower filters, and then put the solution in the filter filter. A new filter must be used for each filter, and the structure of the Cai filter is shown in Figure VI.-2. The structure of the membrane filter is similar to that of the Cai filter, except that the membrane is a porous cellulose (acetic cellulose or nitrate cellulose), the aperture is generally 0.45 m, when the filter, liquid and small molecular substances pass through, bacteria are intercepted on the membrane, but to remove the virus, a smaller pore membrane is required., ultraviolet sterilization
ultraviolet wavelength in 200-300 nm, has sterilization effect, of which 265-266 nm sterilization force is strongest. Aseptic chamber or sterile inoculation box air can be sterilized with ultraviolet light., chemical sterilization
chemical disinfection method is the application of chemical agents that can kill microorganisms for disinfection and sterilization methods. Laboratory desktops, appliances, and hand-washing solutions are commonly disinfected and sterilized with chemicals. Commonly used are 2% coal phenol soap solution (Tosul), 0.25% neo-steril, 1% mercury, 3-5% formaldehyde solution, 75% alcohol solution, etc.range and concentration of commonly used chemical fungicides can be found in Table VI.-1.