High-level disinfection processes for endoscope
reprocessing need to kill all forms of bacteria
(gram-positive, gram-negative and mycobacteria),
viruses (both the more sensitive lipid-coated
viruses such as HIV and relatively resistant viruses
such as the polio virus), fungi (e.g. Candida spp.)
and protozoa (e.g. Giardia) within a practicable
contact time. High-level chemical disinfectants
alone are able to kill the more resistant forms of
microbial life such as bacterial spores and cysts
but only with prolonged contact times (usually
over 3 hours). Heat alone is also an effective
disinfectant; for example temperatures 70°c for
100 minutes are used for pasteurisation. With
high levels of wet heat and pressure (autoclaving),
sterilisation is achieved. Many reprocessing
systems for endoscopes use a combination of
chemicals and modest heat to achieve high-level
disinfection.