They may injure the cell membrane altering the normal selective permeability allowing metabolically important components to escape, or prevent the entrance of food. Also, they may react with a specific enzyme to prevent it from reacting with its natural substance. There is a wide range of resistance of microorganism to inactivating agents. Most vegetative bacteria, fungi, and lipid containing viruses are relatively susceptible to chemical decontamination. The non-lipid containing viruses and bacteria with a waxy coat occupy a midrange of resistance.
Spore forms are the most resistant.
Methods of Sterilization Steam Sterilization Autoclaving is except where penetration of heat and moisture damage is a factor. Most organisms can be destroyed in the presence of steam under pressure at 121 o C for a minimum of 15 minutes. The major problem to insuring the reliability of this method other than time and temperature is the prevention of air entrapment. Air must be replaced by the steam and adequate exposure time as related to the soil load on contaminated items. Downward or gravity displacement takes advantage of the difference in density of air relative to steam.