Sterilisation Chemical agent Flashcards
Name chemical agents used for sterilisation and disinfection
Chemical sterilants: •Formaldehyde •Ethylene oxide •Betapropiolactone Gaseous sterilants •Gas plasma Gluteraldehyde ( Not gas) •These are used for sterilization of delicate heat labile equipments
Chemical disinfectant: 1.Alcohols: Ethyl, Isopropyl 2.Aldehydes: Formaldehyde,Glutaraldehyde 3.Dyes 4.Halogens 5.Phenols 6.Surface-active agents 7.Metallic salts
What are the factors which determine the potency of disinfectant?
Choose the disinfectant carefully •2) Prepare the disinfectant properly •Disinfectants need to be diluted or activated •3) Clean before disinfecting •Washing would remove most of the micro-organisms, remove some organic matters •4) Know the minimum effective time •Exposing the materials for less period of time would mean that not all micro-organisms would be killed
Explain the use and action of following chemical agents: a. Ethylene oxide,
Betapropiolactone, c. Alcohols, d. Aldehydes, e. Halogens, f. Phenols
Ethylene oxide:
Mode of action: Alkylating agent Uses: To sterilize •Heart-lung machines •Respirators, sutures •Dental equipment •Books and clothing
Betapropiolactone (BPL): •It has low penetrating power •It has a rapid biocidal activity •Kills all microorganism including viruses but carcinogenic
Alcohols:Used as skin antiseptics •Act by denaturing bacterial proteins
Aldehydes:It is bactericidal, sporicidal and virucidal •Used to preserve anatomical specimens, and for destroying anthrax spores
Halogens: Iodine in aqueous and alcoholic solution has been used as a skin disinfectant •It is actively bactericidal, virucidal, and sporicidal
Phenols:Mode of action: Causes cell membrane damage which result in cell lysis
Used as disinfectants for various purposes in hospitals but are toxic
What are the main modes of action of chemical disinfectant?
Protein coagulation 2. Disruption of cell membrane resulting in exposure, damage or loss of the contents 3. Removal of free Sulphydryl groups essential for the functioning of the enzymes 4. Substrate competition: a compound resembling the essential substrate of the enzyme diverts or misleads the enzymes and causes cell death
What is Rideal Walker test?
Two sets of Suspensions containing equal numbers of typhoid bacilli are prepared •One set is submitted to the action of varying concentration of phenol •Other set is submitted to varying concentration of the disinfectant to be tested.The dilution of the test disinfectant, which sterilizes the suspension in a given time •Is divided by the corresponding dilution of phenol • Is the phenol coefficient of the disinfectant.
Write a note on Waste disposal in the laboratory
Inefficient disposal of contaminated materials and waste can lead to infection of the public •We may unknowingly or unintentionally “re-cycle” pathogens in the air thereby causing infection in the community •Waste products fall into two classes •1.Disposable wastes •2.Re-usable wastes
Disposable wastes: Materials, which we may not use again or should never have need to use again •Never ever discard a contaminated disposable material without first decontaminating it •They go through a process of decontamination either by disinfection or autoclaving •Then they can be incinerated or they are disposed of by throwing them into a pit (Land fill)
Reusable materials: These are things like glassware, instruments like metal spatulas, equipments, graduated glass pipettes which we want to recover and reuse •After washing these materials they are prepared for further use and sterilized in another “clean” autoclave •There are three methods for treating wastes: •Autoclaving •Chemical disinfection •Incineration
What is meant by Disposable wastes and Re-usable wastes in the laboratory?
Disposable wastes: Materials, which we may not use again or should never have need to use again
Reusable materials: These are things like glassware, instruments like metal spatulas, equipments, graduated glass pipettes which we want to recover and reuse •After washing these materials
Name the three methods for treating wastes . Explain each method
Autoclaving •Chemical disinfection •Incineration
