Sterilisation is the destruction of all microbial life, including highly resistant bacterial endospores, using a chemical or physical process. Disinfection is a less thorough procedure and involves the removal of most, but not all, microbial life. Chemical germicides are usually used as disinfectants. In hospital, the major sterilisation techniques used include:
moist heat by steam autoclaving. Spores take the longest time to kill and the time taken is temperature and pressure dependent. This technique is suitable for sterilising most heat-resistant surgical instruments
dry heat via a hot air oven. This relies on conduction of heat rather than heat transfer through condensation. It requires higher temperatures and longer times than moist heat and so is not appropriate for heat-sensitive materials
ethylene oxide gas sterilises at 55°C and so can be used to sterilise heat-sensitive instruments. The gas is toxic by contact and explosive
irradiation is used to sterilise many single-use products such as syringes
chemical germicides are used to sterilise heat-sensitive instruments.