Equipments and Sterilization

Sterilization refers to any process that effectively kills or eliminates transmissible agents (such as fungi, bacteria, spores, viruses and prions) from a surface, equipment, foods, medications, or biological culture medium. Heat sterilization of medical instruments is known to have been used in Ancient Rome, but it mostly disappeared throughout the Middle Ages resulting in significant increases in disability and death following surgical procedures. The various agents used in sterilization are divided into 2 categories :-

Physical agents- like sunlight, drying, dry heat(flaming, incineration, hot air), moist heat(pasteurization, boiling, tyndallization, steam, and steam under pressure), filtration(candles, asbestos pads, membranes), radiation, ultrasonic and sonic vibrations.

Chemical agents-like alcohols (ethyl, isopropyl, trichlorobutanol), aldehydes (formaldehyde, glutaraldehyde), dyes, halogens, phenols, surface active agents, metallic salts..

Heat is the most reliable method of sterilization and should be the method of choice unless contraindicated. Commercial plants use gamma radiation(cold sterilization)for mass sterilizing products like plastics, syringes, swabs, catheters, animal feeds, cardboards, oils, grease, fabrics and metal foils. Chemical agents are mostly used as antiseptics and disinfectants. Irradiation is used by the United States Postal Service to sterilize mail in the Washington, DC area.