disinfection.presentation slideshare ptx
- 2. Definition: The selective elimination of certain undesirable organisms in order to prevent their transmission, achieved by action on their structure or metabolism, irrespective of their functional state. Disinfection does not necessarily kill all microorganisms but reduces them to a level acceptable for a defined purpose. (British standards)
- 3. An ideal disinfectant should: Have a wide spectrum of activity Be active in the presence of organic matter Have speedy action High penetrating power Be stable Not be toxic Not corrosive inexpensive
- 4. Factors determining the potency of disinfectant: Concentration of the substance Time of action pH of the medium Temperature Nature of the organisms Presence of extraneous material
- 5. Chemical agents 1. Alcohols: Ethyl, isopropyl, methyl 2. Aldehydes: Formaldehyde, Glutaraldehyde 3. Dyes 4. Halogens 5. Phenols 6. Surface active agents 7. Metallic salts 8. Gases: Ethylene oxide, Formaldehyde, Beta propiolactone.
- 6. HIGH: Kills all the organisms except high number of Spores, Prions – Eg. Aldehydes, ethyleneoxide INTERMEDIATE: Kills Mycobacteria, most viruses and bacteria, fungi but not spores – Eg. Iodine, ethanol, chlorine LOW: Kills some viruses and bacteria but not mycobacteria, spores – Eg. Quarterly ammonium compounds, mercurials. LEVELS OF DISINFECTION:
- 7. ALCOHOLS: Ethyl alcohol Methyl alcohol Isopropyl alcohol Bactericidal, tuberculocidal, fungicidal, virucidal. Donot act on spores Optimum concentration is 60 – 90 % Mechanism of action: denaturation of proteins
- 8. Microbicidal activity: Pseudomonas 10 sec 30 – 100% E.coli, S.typhi 10 sec 40 – 100 % S.aureus, Strep. pyogenes 10 sec 60 – 95%
- 9. Ethyl alcohol (60 – 80%) is virucidal for all lipophilic viruses and hydrophilic viruses except hepatitis A and polio virus Isopropanol is active against all lipophilic viruses. 70% ethanol is active against cryptococcus, blastomyces, coccidiodes 20% isopropanol is used for killed cysts of acanthamoeba
- 10. Uses: ◦ Oral thermometers ◦ Scissors ◦ Sthethescopes Disadvantages: As they lack sporicidal action, they are not recommended for equipments and surgical materials. They damage the lensed instruments and tonometer tips. Methyl alcohol is toxic and not used nowadays.
- 11. CAVI WIPES:
- 12. Low alcohol (17% isopropanol) surface disinfectants: non abrasive towelettes easy to use ideal for operating rooms, surgical centres, neonatal centres saves time and convenient
- 13. ALDEHYDES: Formaldehyde Glutaraldehyde Ortho – phthalaldehyde Formaldehyde: Bactericidal, sporicidal, virucidal Used to preserve specimens For destroying anthrax spores in hair and wool 10% formalin containing 0.5% sodium tetraborate is used to clean metal
- 14. Formalin:
- 15. Glutaraldehyde: High level disinfectant & chemical sterilant In aqueous solutions – not sporicidal if activated by using alkalinising agents to change the pH to 7.5 to 8.5 becomes sporicidal
- 16. Disadvantage of activation: Once activated the shelf life of glutaraldehyde is only 14 days and after that polymerisation of the glutaraldehyde molecules takes place and it blocks the active aldehyde groups. To overcome the above problem: Glutaraldehde phenol sodium phenate or stabilised alkaline glutaraldehyde can be used.
- 17. Mechanism of action: Alkylation of sulfhydryl, hydroxyl, carboxyl and amino groups of micro organisms which alter the RNA,DNA and protein synthesis
- 18. > 2% aqueous solution of glutaraldehyde buffered to alkaline pH with sodium bicarbonate kills: Vegetative bacteria <2 min TB, Fungi, Viruses < 10 min Bacillus, Clostridial, spores 3 hours
- 19. Uses: Endoscopes,Spirometry,Dialyzers,Transducers ,Anaesthesia equipments ,Plastic trocars. Advantage: non corrosive Disadvantage: ◦ If not properly cleansed- colitis occurs in endoscopy patients ◦ In eye equipments – keratopathy ◦ Health care workers with chronic exposure – dermatitis, asthma and rhinitis
- 20. Endoscope:
- 21. Glutaraldehyde disposal: If glutaraldehyde disposal is restricted through the sanitary sewer system, sodium bisulfate can be used to neutralise glutaraldehyde and make it safer for disposal TRADE NAMES: cidex, Asep, clinicide, totacide, triocide
- 22. Ortho-phthalaldehyde: High level disinfectant Superior than glutaraldehyde Excellent stability over wide range of pH Not irritant No need of activation
- 23. DYES: Aniline dyes - Brilliant green, malachite green, crystal violet - more active against gram positive - non toxic, non irritant - inactivated by organic material (pus) Acridine dyes - Proflavine, acriflavine, euflavine, aminacrine - active against gram positive
- 24. HALOGENS: Bactericidal, virucidal and sporicidal CHLORINE: - used as chlorine tablets for disinfection of water - sodium hypochlorite for disinfection of equipment soiled with blood
- 26. Hypochlorites: Readily inactivated by organic material Corrosive to metals and textiles Should not be mixed with acids, as they emit toxic amounts of chlorine gas Very active against bacteria, viruses including HIV and HBV Trade names: chloros, domestos, diversol BX, milton
- 27. Iodine: Iodine is more sporicidal than chlorine Used in aqueous and alcoholic solution as skin disinfectant Eg. Povidone iodine preparations Iodophores: Organic compounds that slow the release of iodine. Steadily supplies the iodine over long periods, increases the penetration, more active.
- 29. Phenols: Phenol was initially used by Lister as a germicide in his pioneering work on antiseptic surgery. Mechanism of action: Protoplasmic poison – penetrates the cell wall and precipitates the cell proteins.
- 31. Active against bacteria, mycobacteria but little activity against endospores, viruses Will not inactivate HIV within 30min Resistant to inactivation by organic matter Activity reduced in alkaline pH Useful to disinfect environmental surfaces Names: Clearsol, hycolin, stericol, lysol, dettol
- 32. Phenolics – disadvantage : Phenolics in nurseries causes hyperbilirubinemia in infants. If phenolics are used to terminally clean infant bassinets and incubators, the surfaces should be rinsed throughly with water and dried before reuse of infant bassinets and incubators
- 33. FORMALDEHYDE FUMIGATION : Commonly used to sterilize the OT. Requirement (For an area of 1000 cubic feet) - 500 ml of 40% formaldehyde in one liter of water - Stove or hot plate for heating formalin - 300 ml of 10% Ammonia
- 34. Procedure Close all doors & windows air tight and switch off fans and A.C. Heat formalin solution till boiling dry Leave the OT unentered over night Enter the OT next day morning with 300ml of ammonia Keep the ammonia solution for 2-3 hrs to neutralize formalin vapours Open the OT to start surgery Advised fumigation at weekly intervals
- 36. Mode of Action Formaldehyde inactivates microorganisms by alkylating the aminoacid and sulfhydryl groups of proteins and ring nitrogen atoms of purine bases. Disadvantages It acts as a potential carcinogen Toxic Irritant
- 37. Duration: In case of any construction in O.T. 48 hrs In case of infected cases 24hr For routine clean cases 12 hrs. Alternatively 250 ml of formalin and 3000 ml of tap water are put into a machine (auto mist) and time is set for 2 hrs. The mist is circulated for 2hrs inside the closed room.
- 38. Commercially available disinfectant Baccilocid rasant A newer and effective compound in environmental decontamination with very good cost/benefit ratio, good material compatibility, excellent cleaning properties . It is a Formaldehyde-free disinfectant cleaner with low use concentration. Active ingredients: Glutaral 100 mg/g, benzyl-C12-18- alkyldimethylammonium chlorides 60 mg/ g, didecyldimethylammonium chloride 60 mg/g.
- 39. Aldekol A new method of fumigation has been evolved using ‘Aldekol’, a mixture containing 6% formaldehyde, 6% glutaraldehyde and 5% benzalkonium120 chloride
- 40. Advantages - Provides complete asepsis within 30 to 60 minutes. - Cleaning with detergent or carbolic acid not required. - Formalin fumigation not required. - Shutdown of O.T. for 24 hrs not required.
- 41. Ethylene Oxide : Widely used for re -sterilizing ‘packaged heat sensitive devices’ like sharp knives and blades. It is non-corrosive and safe for most plastic and polyethylene materials. It is the preferred method for sterilizing heat labile tubings, vitrectomy cutters, cryoprobes, light pipes, laser probes, diathermy leads, Gas:
- 43. Ethylene oxide sterilisation: cold cycle - 37±5ºC Warm cycle – 54 ±5ºC In these cycles, the relative humidity is maintained at 40 to 50% and ethylene oxide concentration is kept at 700mg/litre. Testing of ethylene oxide steriliser: Bacillus subtilis subsp niger
- 44. Hydrogen peroxide: Bactericidal, virucidal – 1 minute sporicidal, fungicidal – 5 minutes Mechanism of action: Targets cell wall, cytoplasm Works by producing destructive hydroxyl free radicals that can attack membrane lipids, DNA.
- 45. Hydrogen Peroxide which must be diluted to a 6% solution, is less expensive . The 3% H2O2 solutions used as antiseptics, however, should not be used as a disinfectant. For disinfecting soft contact lenses, tonometer biprisms, ventilators, fabrics, endoscopes.
- 46. Disadvantages: H2O2 soaked tonometer tip caused corneal damage. Gastrointestinal endoscopy unit rinsing with 3% H2O2 caused enteritis & pseudomembranous colits.
- 47. Surface active agents: Substances that alter the energy relationship at interfaces, producing a reduction of surface or interfacial tension. Classification: anionic, cationic, non-ionic and amphoteric
- 48. Mechanism of action: Act on the phosphate groups of the cell membrane and enter the cell. Common compounds: Acetyl trimethyl ammonium bromide (cetavlon) Benzalkonium chloride
- 49. Disinfection of spillages: Contamination with Blood – hypochlorite 5%-10% ( 10,000ppm ) – contact period 30 min Liquid spillages – immediately cover with a disposable cloth or absorbent paper soaked in disinfectant and leave for 10 min. The area should be rinsed with fresh disinfectant and dried.
- 50. Disinfection of rooms: Formaldehyde vapours
- 51. Disinfection of safety cabinets: Safety cabinets should be washed down with an appropriate disinfectant after each day`s use. When fittings are done or filters are changed – fumigation is necessary Place 25ml formaldehyde solution in an electrically heated dish inside the cabinet. Replace the front closure of the cabinet and if necessary, seal with
- 52. Vaporize the formaldehyde and leave the cabinet closed overnight The next day, switch on the extract fan to remove the formaldehyde vapour and expel it through the HEPA filter into the exhaust duct. Open the front closure Remove the front closure and check the rate of airflow before using the cabinet
- 53. Disinfection of sputum: Autoclaving is the best method Incineration or burning Sputum container disinfection: - Autoclaving - put in hypochlorite or 5%phenol in bucket then incinerate or dump in dump hole
- 54. Sporicidal agents: Glutaraldehyde Formaldehyde Halogens Ethylene oxide Peroxygens Betopropiolactone
- 55. Skin disinfectants / antiseptics: Povidone iodine Isopropyl alcohol Chlorhexidine (hibitane) Quaternary ammonium compounds Peroxides Phenol and its derivatives Quinolone derivatives
- 56. Disinfection – HIV: HIV is completely inactivated by treatment for 10minutes at room temperature with any of the following: 10% household bleach 50% ethanol, 35% isopropanol 0.5% lysol 0.3% hydrogen peroxide
- 57. Thank you…….