Endoscopes (e.g., cystoscopes, gastroscopes) should sterilized with
Ans. a (Glutaraldehyde) (Ref. Ananthanarayan Microbiology 7th/pg. 31, 86)Most rigid endoscopes are compatible with steam, formaldehyde, ethylene oxide and certain liquid chemical disinfectants. Flexible scope can be sterilized by peracetic acid.CHEMICAL STERILIZATION# Ethylene oxide (EO or EtO) gas- Most common sterilization method .- Used to sterilize objects sensitive to temperatures > 60degC such as plastics, optics and electrics.- Carried out at 30-60degC with relative humidity >30% & gas cone. 200-800 mg/L for at least 3 hrs.- ETO penetrates well, moving through paper, cloth, and some plastic films and is highly effective.- EtO can kill all known viruses, bacteria and fungi; including bacterial spores and is satisfactory.- Bacillus subtilis, a very resistant organism, is used as a rapid biological indicator for EO sterilizers.# Glutaraldehyde# Glutaraldehyde is a saturated dialdehyde that has gained wide acceptance as a high-level disinfectant and chemical sterilant.# It is specifically effective against tubercle bacilli, fungi, and viruses.# Has a short shelf life (<2 weeks), and is expensive.# It is less toxic and irritant to eyes than formaldehyde.# To kill all spores in liquid can take upto 12 hrs with gluteraldehyde & longer with formaldehyde.# It has no deleterious effect on the cement or lenses of instruments like cystoscopes and bronchoscopes.# It can safely be used to treat corrugated rubber anesthetic tubes and face masks, plastic endotracheal tubes, polythene tubing, and metal instruments.# CIDEX (2% gluteraldehyde) is commonly used for sterilization of endoscopes.# Formaldehyde# It is less expensive and has a much longer shelf life, but is much more volatile.# Formaldehyde is also used as a gaseous sterilizing agent.# Many vaccines, such as the original Salk polio vaccine, are sterilized with formaldehyde.# Ozone is used in industrial settings to sterilize water and air, as well as a disinfectant for surfaces. It has the benefit of being able to oxidize most organic matter. On the other hand, it is a toxic and unstable gas that must be produced onsite, so it is not practical to use in many settings.# Chlorine bleach is another accepted liquid sterilizing agent. Household bleach consists of 5.25% sodium hypochlorite. It is usually diluted to 1/10 immediately before use; however to kill Mycobacterium tuberculosis it should be diluted only 1/5. The dilution factor must take into account the volume of any liquid waste that it is being used to sterilize. Bleach will kill many organisms immediately, but for full sterilization it should be allowed to react for 20 minutes. Bleach will kill many, but not all spores. It is highly corrosive and may corrode even stainless steel surgical instruments.# Chlorine and NaOH are the most consistent agents for prions. Chlorine is too corrosive to use on certain objects. NaOH has had many studies showing its effectiveness.
Glutaraldehyde
Ethylene oxide
Benzalakonium
Betapropiolactone
General