Other Method of Sterilization

Technology has brough about different method of sterilization to combat spread of infections and to address sterilization requirement of different materials. Here are some of the most common method being used in the hospital and other facility where infection control is required.

1. Steam Sterilization - it is the most common method of sterilization. Mainly due to its economy, ease of use, environment friendliness, and can deal with wide range of materials. Items to be sterilized are subjected to around 125°C of steam at 30 psi for around 15 to 45 minutes. It can sterilize materials that can withstand those extreme in pressure and temperature without alteration to its chemical component or physical appearance.
2. Gas Sterilization - is used to sterilized those that cannot be subjected to steam or radiation. It use Ethyline Oxide (EtO) or Formaldehyde as sterilant and is considered to harmful to human. Certain level of ventilation is required for this type of sterilization. This process is very costly and time consuming as the item has to be aerated properly after sterilization. It is being used to sterilize rubber, plastics, powder, etc.
3. Gamma Irradiation - is usually being done on a nuclear facility and is therefore used less than the first two. It is being used for those item that cannot be subjected to extreme pressure and temperature and has reactions to gas sterilant.
4. Dry Heat Sterilization - Dry heat is less efficient than wet heat sterilization and requires longer times and/or higher temperatures. The specific times and temperatures must be determined for each type of material being sterilized. Generous safety factors are usually added to allow for the variables that can influence the efficiency of this method of sterilization. The moisture of the sterilization environment as well as the moisture history of organisms prior to heat exposure appear to affect the efficiency of dry heat sterilization.
   Higher temperatures and shorter times may be used for heat resistant materials. The heat transfer properties and the spatial relation or arrangement of articles in the load are critical in insuring effective sterilization.
   The advantage of wet heat is a better heat transfer to and into the cell resulting in overall shorter exposure time and lower temperature. Steam sterilization uses pressurized steam at 121-132° C (250-270° F) for 30 or 40 minutes. This type of heat kills all microbial cells including spores, which are normally heat resistant. In order to accomplish the same effect with dry heat in an oven, the temperature needs to be increased to 160-170° C (320-338° F) for periods of 2 to 4 hours