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  1. 1. Dr. Khem R. Sharma Assistant Professor School of Public Health & Community Medicine DISINFECTION & DISINFECTANTS
  2. 2. Objectives  After this SIS every one of you will be expected to be able to:  Define the term, “disinfection,” and explain how disinfection differs from sterilization  Understand the types of disinfection  Review factors that impact the effectiveness of a disinfectant  Distinguish between high-level, intermediate-level & low-level disinfection.  Identify the properties of an ideal disinfectant  Gain knowledge on the Disinfection agents (Disinfectants)
  3. 3. Introduction  Disinfection is the process of killing infectious agents except spores outside the body by direct exposure to chemical or physical agents.  It can refer to the action of antiseptics as well as disinfectants.  Sterilisation - process by which an article, surface or medium is made free of all living microorganisms including spores.
  4. 4.  A disinfectant is a substance which destroys harmful microbes (except spores) with the object of preventing transmission of infection.  Disinfectants are only suitable for application on inanimate objects.  Antiseptics - Chemicals used on living tissue such as skin, to kill or slow the growth of microorganisms. Introduction
  5. 5. A brief History  Early civilization practiced methods like salting, smoking, pickling and exposure to sunlight to prolong shelf life of foods.  Semmelweis (1818-1865) – demonstrated the value of hand- washing with antiseptic solutions to reduce the death rate from puerperal fever.  Lister (1927-1972) was successful in reducing the number of wound infections by prophylactic application of carbolic acid.
  6. 6. Types of Disinfection 1) Concurrent disinfection : It is the application of disinfective measures as soon as possible after the discharge of infectious material from the body of an infected person.
  7. 7. 2) Terminal disinfection: Application of dis-infective measures after the patient has been removed by death or to a hospital or has ceased to be a source of infection or after other hospital isolation practices have been discontinued. Rarely practiced today. 3) Precurrent (prophylactic) disinfection: Disinfection of water by chlorine, pasteurization of milk and handwashing may be cited as examples of precurrent disinfection. Types of Disinfection
  8. 8. Chemical Disinfection Cidal - chemical agents capable of killing bacteria. Agents that are bactericidal, virucidal, fungicidal or sporicidal are capable of killing these organisms. Static - Chemical agents that inhibit the growth of bacteria but do not necessarily kill them.
  9. 9. Properties of an Ideal Disinfectant  Broad spectrum  Fast acting  Not affected by environmental facters  Nontoxic  Surface compatibility  Residual effect on treated surfaces  Easy to use with clear lebel directions  Odourless  Ecological  Solubility  Cleaner , Environmentally friendly.
  10. 10. Factors Impacting the Effectiveness of Disinfectants  Excessive Moisture  Excessive moisture can cause disinfectant solutions to become diluted.  Lowering the concentration of the chemical disinfectant can reduce its ability to kill microorganisms  Type and number of microorganisms present
  11. 11. Factors Impacting the Effectiveness of Disinfectants:  Direct Contact with the Item  In order to be effective, disinfectants must make direct contact with all surfaces being disinfected  Time  Disinfectants must be allowed some time to work  Check manufacturer’s instructions for the correct exposure time required to achieve the desired biocidal effect
  12. 12.  Temperature of the Disinfectant  pH  Hardness of the Water  Material Compatibility  Positioning of the Device(s) being disinfected Other Factors Impacting the Effectiveness of Disinfectants
  13. 13. Selecting a Disinfectant  Should be based on: ◦ The intended use of the device ◦ The degree of disinfection required for the device ◦ Risk levels
  14. 14. Critical Items  Items introduced directly into the bloodstream or other normally sterile areas of the body  Surgical Instruments, Implants, etc.
  15. 15. Semi-Critical Items  Items which come in contact with intact mucous membranes  Fiberoptic Endoscopes, Cystoscopes, etc.
  16. 16. Non-Critical Items  Come in direct contact with the patient’s unbroken skin  Crutches, Blood Pressure Cuffs, equipment, etc.
  17. 17. Classification of Patient Care Items Body Contact Activity Level Item Class Intact skin Low level Non-critical Mucous membranes Intermediate level Semi-critical Sterile body cavity High level Critical
  18. 18. Disinfectant Activity Levels  High-level  Intermediate-level  Low-level
  19. 19. High level disinfection  This processes destroy vegetative bacteria, mycobacteria, fungi and enveloped (lipid) and non-enveloped (non lipid) viruses, but not necessarily bacterial spores.  High level disinfectant chemicals (also called chemical sterilants) must be capable of sterilization when contact time is extended.  Items must be thoroughly cleaned prior to high level disinfection.
  20. 20. Intermediate level disinfection Intermediate level disinfectants kill vegetative bacteria, most viruses and most fungi but not resistant bacterial spores.
  21. 21. Low level disinfection  Low level disinfectants kill most vegetative bacteria and some fungi as well as enveloped (lipid) viruses (e.g., hepatitis B, C, hantavirus, and HIV).  Low level disinfectants do not kill mycobacteria or bacterial spores.  Low level disinfectants are typically used to clean environmental surfaces.
  22. 22.  Wear PPE  Use an exhaust hood when necessary  Develop a spill plan  Provide an eyewash/shower and other first aid supplies  Provide easy access to a phone and phone numbers for emergencies  Provide yearly staff training  Monitor disinfectants (including air quality) Chemical Disinfectant Safety
  23. 23. Disinfectants 1) Natural Agents  Sunlight, Air 2) Physical Agents  Burning  Hot Air  Boiling  Autoclaving  Radiation Many disinfectants are used alone or in combinations in the health-care setting.  Chemical Agents  Alcohols  Chlorine and Chlorine compounds  Formaldehyde  Glutaraldehyde  Ortho-phthalaldehyde,  Hydrogen peroxide  Iodophors  Peracetic acid  Phenolics  Quaternary ammonium compounds.
  24. 24. Natural Agents  Sunlight: Direct and continuous exposure to sunlight is destructive to many disease producing organisms.  Air: Exposure to open air (airing) acts by drying or evaporation of moisture which is lethal to most microorganism.
  25. 25. Physical Agents  Burning/incineration is an excellent method of disinfection.  Hot air sterilization is usually done in a hot air oven & is very useful for sterilizing articles such as glassware, syringes, swabs & dressings.  Boiling is an effective method of disinfection which provides an atmosphere of boiling and steam.  The drawbacks of boiling are that it is a slow process, unsuitable for thick beddings and woolen materials as they shrink.
  26. 26.  Autoclaving: It generates steam under pressure (saturated steam) which is the most effective sterilizing agent.  Basically, the autoclave works on the same principle as the domestic pressure cooker  Ionizing radiation has great penetrating powers with little or no heating effect making it one of the most viable, safe and economic methods used today.. Physical Agents
  27. 27. Alcohol denaturation of proteins  Alcohols are commonly used topical antiseptics. Rapid bactericidal, tuberculocidal, fungicidal, and virucidal but do not destroy bacterial spores.  optimum bactericidal concentration is 60%–90% solutions in water.  Alcohols are not effective against bacterial spores and have limited effectiveness against nonenveloped viruses.  They are also used to disinfect the surface of medical equipment. Alcohols require time to work and they may not penetrate organic material.
  28. 28. • They have a broad spectrum of antimicrobial activity, do not leave toxic residues, are unaffected by water hardness. • Hypochlorite, the most widely used of the chlorine disinfectants, are available as liquid or solid. • The most common chlorine products in are aqueous solutions of 4 to 6% sodium hypochlorite, which are readily available as “household bleach”. Chlorine and Chlorine Compounds (Hypochlorite)
  29. 29.  Hypochlorite Most recommended in They are included in most recommendation for decontamination of hepatitis and AIDS viruses .  Hypochlorite are also the agent of choice in disinfecting surfaces used for food preparation or in bathrooms.  Organic material such as feces or blood inactivate chlorine based disinfectants, therefore, surfaces must be clean before their use. Chlorine and Chlorine Compounds (Hypochlorite)
  30. 30.  Formaldehyde is used as a disinfectant and sterilants in both its liquid and gaseous states.  The aqueous solution is a bactericide, tuberculocide, fungicide, virucidal and sporicidal. Formaldehyde formalin
  31. 31. Formaldehyde  Mode of Action. Formaldehyde inactivates microorganisms by alkalizing the amino and sulfhydral groups of proteins and ring nitrogen atoms of purine bases.  Be careful in handling Formaldehyde, wear mask (irritant and potential carcinogenic )
  32. 32. Glutaraldehyde high-level disinfectant and chemical sterilant  Aldehydes have a wide germicidal spectrum.  Gluteraldehydes are bactericidal, virucidal, fungicidal, sporicidal and parasiticidal.
  33. 33. Glutaraldehyde  They are used as a disinfectant or sterilant in both liquid and gaseous forms.  Glutaraldehyde is used most commonly as a high-level disinfectant for medical equipment such as endoscopes.  Glutaraldehyde should not be used for cleaning Noncritical surfaces because it is too toxic and expensive.
  34. 34. Hydrogen Peroxide 3% hydrogen peroxide is a stable and effective disinfectant when used on inanimate surfaces.  Peroxides such as hydrogen peroxide are often used as antiseptics to clean wounds.  The activity of peroxides is greatest against anaerobic bacteria.
  35. 35. Hydrogen Peroxide  Hydrogen peroxide at high concentrations is in some cases is damaging to tissues, resulting in a prolonged healing time.  It is useful for cleaning surgical sites after closure, but use sparingly to avoid penetrating suture lines, which would inhibit healing.
  36. 36. Iodine  The best-known and most widely used iodophor is povidone-iodine.  Mode of Action. Iodine can penetrate the cell wall of microorganisms quickly, and the lethal effects are believed to result from disruption of protein and nucleic acid structure and synthesis.
  37. 37. Ortho-phthalaldehyde (OPA)  Ortho-phthalaldehyde is a high-level disinfectant  OPA solution is a clear, pale-blue liquid with a pH of 7.5.  advantages: excellent stability over a wide pH range (pH 3–9)  not a known irritant to the eyes and nasal passages, does not require exposure monitoring, has a barely perceptible odor
  38. 38. Peracetic Acid  rapid action against all microorganisms.  Special advantages of peracetic acid are that it lacks harmful decomposition products  It remains effective in the presence of organic matter and is sporicidal even at low temperatures Uses. An automated machine using peracetic acid to chemically sterilize medical (e.g., endoscopes, arthroscopes), surgical, and dental instruments.
  39. 39. Peracetic Acid and Hydrogen Peroxide  combination of peracetic acid and hydrogen peroxide inactivated all microorganisms except bacterial spores within 20 minutes.  The 0.08% peracetic acid plus 1.0% hydrogen peroxide product effectively inactivated glutaraldehyde-resistant mycobacteria. Peracetic Acid
  40. 40. Phenolics  In high concentrations, phenol acts as a gross protoplasmic poison, penetrating and disrupting the cell wall and precipitating the cell proteins.  Pure phenol is not an elfective disinfectant & is used as a standard to compare the germicidal activity of disinfectants  Phenolics are bactericidal, fungicidal, virucidal, and tuberculocidal (low level disinfectant).
  41. 41. Quaternary Ammonium Compounds  The quaternary ammonium compounds are widely used as disinfectants and good cleaning agents.  Mode of Action. The bactericidal action of the quaternaries has been attributed to the inactivation of energy-producing enzymes, denaturation of essential cell proteins, and disruption of the cell membrane.  Uses. The quaternaries commonly are used in ordinary environmental sanitation of Noncritical surfaces, such as floors, furniture, and walls.
  42. 42. Chlorhexidine Chlorhexidine products are often used as disinfectants for inanimate objects or antiseptics for cleaning skin wounds.  Skin Antisepsis: 0.5% Chlorhexidine Skin Preparation with Alcohol.  Low toxicity  Used in disinfection of the skin and hands & mucous membranes
  43. 43. No disinfectant is substitute for the following procedures  Hand washing (hand hygiene)  The use of personal protective equipment (e.g. gloves) when handling blood, body substances excretions and secretions.  Appropriate handling of patient care equipment and soiled linen.  The prevention of needle stick/sharp injuries.  Environmental cleaning.  Appropriate handling of medical waste.  Taking care of yourself (e.g. immunization)
  44. 44. Hands Spread Disease