Ans. a (Glutaraldehyde). (Ananthnarayan, Microbioloyg, 4th ed., 32)SterilisationSterilisation by steam (Autoclave)Sterilisation by hot airSterilisation by ethylene oxideSterilization by low-temperature steam and formal dehydeSterilisation by irradiation- Vegetative bacteria, including tuberculosis, and viruses such as hepatitis B, hepatitis C and HIV and heat-resistant spores, including C.tetani and C.perfringens, are killed.- Combination of pressure, temperature and time with the moist heat is important: 134degC (30 lb/in.2) for a hold time of 3 minutes; 121degC (15 lb/in.2) for a hold time of 15 minutes;- Monitoring=Steam penetration/Bowie - Dick test and chemical indicators, for example Brownes tubes or impregnated tapes, are used to ensure that errors. Biological indicators are not appropriate.- Inefficient compared with moist steam sterilisation, but it has ability to treat solid non- aqueous liquids grease/ ointments and to process closed (airtight) containers.- Lack of corrosion may be important, particularly with instruments with fine cutting edges such as ophthalmic instruments.- It cannot be used for substances such as rubber, plastics and IV fluids which are denatured.- ETO is highly penetrative non- corrosive broad- spectrum cidal gas.- It is utilised for heat-sensitive -materials including electrical equipment.- It is not recommended for ventilator respiratory equipment or soiled instruments because organic debris, including serum, has a marked adverse effect.This uses a combination of dried saturated steam and formaldehyde, with the main advantage being that sterilisation is achieved at a low temperature (73degC) and the method is so suitable for heat-sensitive materials and items of equipment with integral plastic components.- It is not recommended for sealed, oily items or those with retained air.- Some plastics and fabrics absorb formal-dehyde, releasing this in a delayed manner which may cause hypersensitivity to the users.- This employs gamma rays or accelerated electrons.- It is an industrial process and is appropriate to the sterilisation of large batches of similar products, such as syringes, catheters and IV cannulas.- Irradiation dose in excess of 25 kGy is accepted as providing adequate sterility assurance.DisinfectionDisinfection with low-temperature steam:- Typical conditions include exposure to dry saturated steam at a temperature of 73degC for a period of 20 minutes at a pressure below atmospheric. Useful for dealing with dirty returns from OT/clinics which may be contaminated with bodily secretions and microorganisms. Following this instruments must be cleaned.Disinfection with boiling water:- Uses soft water at 100()C at normal pressure for 5min. Instruments must be thoroughly cleaned before utilised.Disinfection with formaldehyde:- Formaldehyde gas is a broad-spectrum antimicrobial agent. This process utilises a cabinet which is airtight and circulates gaseous formaldehyde up to 50degC.Disinfection with glutaraldehyde:A 2 % solution of glutaraldehyde is effective against most bacteria, viruses, including hepatitis B and C and HIV, and is a high-level disinfection particularly useful for the decontamination of flexible endoscopes.