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ii. Endoscope cleaning and disinfection Non-immersible endoscopes

have virtually disappeared from clinical practice in the UK and the majority

of gastrointestinal endoscopy units use automated washer/disinfector

machines. The Working Party examined and attempted to define optimal

endoscope cleaning and disinfection procedures with particular reference

to the use of these machines.


The Working Party reviewed the following agents :-

i. 2% glutaraldehyde (eg 'Cidex', 'Asep', 'Totacide 28')

ii. Peracetic acid (eg 'Nu-Cidex' and 'Steris')

iii. Peroxygen compounds (eg 'Virkon')

iv. Chlorine dioxide (eg 'Tristel', 'Dexit', 'Medicide')

v. Quaternary ammonium compounds (eg 'Sactimed Sinald', 'Dettol ED')

vi. Alcohols (eg Ethanol, Isopropanol, Industrial Methylated Spirits)

vii. Superoxidised water (eg 'Sterilox')

(i) Glutaraldehyde 2% activated alkaline glutaraldehyde is effective against

vegetative bacteria, fungi and most viruses (5-8). A two minute exposure

inactivates most infective agents including HIV (9) and enteroviruses (7,10). The

hepatitis B virus is destroyed after 2.5 - 5 minutes (11-13). Although possible

transmission of HCV has been reported after colonoscopy national guidelines for

cleaning were not followed (14). There are no data relating to activity against the

hepatitis C virus, but it is likely that this rather fragile agent will be destroyed

rapidly. Glutaraldehyde destroys high titres of M.tuberculosis within 20 minutes

and lower numbers within 5 - 10 minutes (15,16). M.avium intracellulare is killed

after 60 - 75 minutes (17,18) whilst some bacterial spores require three or more

hours (19). Although little evidence is available, Helicobacter pylori is likely to be

killed rapidly by glutaraldehyde (20), but thorough cleaning is important as this

microorganism may be protected by gastric mucus. Prions are mainly present in

the brain and nervous tissue of patients with transmissible spongiform

encephalopathies e.g. Creutzfeldt-Jakob Disease. Isolation from the blood and

other tissues is likely to be rare. There is no current evidence of transmission

during gastrointestinal endoscopy. However, prions are resistant to instrument

disinfectants, including glutaraldehyde, in the concentrations normally used to

disinfect endoscopes (21). They are also resistant to conventional sterilisation

processes including autoclaving. Thorough cleaning is essential and should

minimise the risk of infection. Endoscopy should preferably be avoided in

patients with known or suspected prion disease.

These data suggest that the previous recommendations concerning endoscopy

in patients suffering from AIDS or other immunodeficiency states were

overcautious. It was stated that endoscopes should be soaked in 2%

glutaraldehyde for one hour prior to their use in these immunocompromised

patients in order to prevent transmission of infection. The most recent

microbicidal data show that a contact period of 20 minutes in 2% glutaraldehyde

should be sufficient for disinfection before and after use in patients with

symptomatic AIDS or other immunodeficiencies. This contact time is also

recommended for clean endoscopes after use in patients with known or

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