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Disinfection in hospitals

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Disinfection in hospitals

Disinfection in hospitals

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  • 1. DISINFECTION IN HOSPITALS Dr.T.V.Rao MDDR.T.V.RAO MD 1
  • 2. WHAT IS DISINFECTION• Disinfection may be defined as: Cleaning an article of some or all of the pathogenic organisms which may cause infection• Perfect disinfectant would also offer complete and full sterilization, without harming other forms of life, be inexpensive, and non-corrosive. Unfortunately ideal disinfectants do not exist. Most disinfectants are also, by their very nature, potentially harmful (even toxic) to humans or animals.DR.T.V.RAO MD 2
  • 3. THE IDEAL DISINFECTANT Resistant to inactivation Broadly active (killing pathogens) Not poisonous (or otherwise harmful) Penetrating (to pathogens) Not damaging to non-living materials Stable Easy to work with Otherwise not unpleasantDR.T.V.RAO MD 3
  • 4. WHY DISINFECTION AND STERILIZATION?• Contagious diseases• Hospital infection (e.g., OR, ID ward) or other opportunistic infection• Lab contamination• Etc.• Microbes:- usually easy to grow in environment;- but also can be inhibited or killed by certain environmental (physical or chemical) factors/conditions. DR.T.V.RAO MD 4
  • 5. TERMINOLOGY• Antisepsis: chemical destruction of vegetative pathogens on living tissue• Degerming: mechanical removal of microbes from limited area• Sanitization: lowering microbial counts on eating and drinking utensils to safe levelsDR.T.V.RAO MD 5
  • 6. TERMINOLOGY• Biocide or germicide: kills microorganisms• Fungicide: kills fungi• Virocide: inactivates viruses• Bacteriostatic agent: stops growth of bacteriaDR.T.V.RAO MD 6
  • 7. ANTISEPTICS VERSUS DISINFECTANTSAntiseptics: Use on skin and mucous membranes to kill microorganisms Not for use on inanimate objectsDisinfectants: Use to kill microorganisms on inanimate objects Not for use on skin or mucous membranes High-level versus low-level disinfectants DR.T.V.RAO MD 7
  • 8. BEGINNING OF SCIENTIFIC ERA OF STERILIZATION AND DISINFECTIONDR.T.V.RAO MD 8
  • 9. DISINFECTION • Process of reducing or eliminating living pathogenic microorganisms in or on materials, so they are no longer a health hazard. For example: use of alcohol before drug injection.DR.T.V.RAO MD 9
  • 10. STERILIZATION• Process of destroying all microbial forms. A sterile object is one free of all microbial forms, including bacterial spores.• More thorough than disinfectionDR.T.V.RAO MD 10
  • 11. SOAP AND DETERGENTS Soaps are sodium or potassium salts of fatty acids, a natural product Detergents, instead, are artificial surfactants While soaps are always negatively charged, some detergents are negatively charged while others are positively charged One example of a positively charged detergent are quaternary ammonium compounds (a.k.a., quats)DR.T.V.RAO MD 11
  • 12. HALOGENS Halogens are the seventh (VII) column of the periodic table of elements Two halogens are regularly employed as antimicrobials: Iodine and Chloride Iodine: commonly used as an antiseptic against all microbes, fungi, and viruses Iodine: It inhibits protein synthesis and oxidizes –SH groups of amino acids Chlorine: Used as a disinfectant (10% bleach) Chlorine: Hypochlorous acid (HOCl) is a product, formed in water, that is the active form of the disinfectant Chlorine: Applied in treatment of drinking water, swimming pool, and sewageDR.T.V.RAO MD 12
  • 13. ANTIMICROBIAL MODES OF ACTION OF DISINFECTANTS AND ANTISEPTICS• Denaturation of bacterial proteins by disrupting hydrogen and disulfide bonds —— phenol (high conc.), alcohol, heavy-metal (high conc.), acids, alkalis, aldehydes)• Damage to bacterial membrane (lipids and/or proteins), causing leakage of intracellular molecules —— phenol (low conc.), surfactants, dyes• Interference of bacterial enzyme and metabolism —— oxidants, heavy-metals (low conc.), alkylating agents DR.T.V.RAO MD 13
  • 14. ALKYLATING PROTEINS AND NUCLEIC ACIDS • Alkylating agent(烷化剂) —— alkylating proteins and nucleic acids • formalin (formaldehyde) —— surface disinfection, air, surgical instruments • glutaric dialdehyde— high- precision instruments, endoscopes • 50mg/L epoxy ethane —— surgical instruments and dressingDR.T.V.RAO MD 14
  • 15. PHENOL AND PHENOL DERIVATIVES • Phenol and phenol derivatives —— altering membrane permeability and denaturing proteins • 0.01% - 0.05% Chlorhexidine)—— vaginal wash, OR hand- wash • 3% - 5% carbonic acid or 2% Lysol —— floor or surface disinfectionDR.T.V.RAO MD 15
  • 16. ALCOHOLS• Alcohols —— denaturing bacterial proteins and membranes • 70% - 75% ethyl or isopropyl alcohol—— skin and thermometer disinfection –ineffective against endospores and non- enveloped virusesDR.T.V.RAO MD 16
  • 17. • Oxidants —— oxidation, protein precipitation • 3% peroxide—— small trauma wound, skin, mucosa • 0.2% - 1% peroxyacetic acid—— plastics, glassware • 0.2 – 0.5 ppm chlorines —— water and swimming pool • 0.1% potassium permanganate—— skin, fruits/vegetablesDR.T.V.RAO MD 17
  • 18. DISINFECTANT EFFECTIVENESS DEPENDS ON MANY FACTORS.• Concentration and quantity of disinfectant. It is important to choose the proper concentration and quantity of disinfectant that is best suited to each situation.• • Contact time and temperature. Sufficient time and appropriate temperature must be allowed for action of the disinfectant and may depend on the degree of contamination and organic matter load .• • Residual activity and effects on fabric and metal should be considered for specific situations.• • Application temperature, pH and interactions with other compounds must be considered.• • Toxicity to the environment and relative safety to people that may be exposed.• • What about Cost ?• 5 DR.T.V.RAO MD 18
  • 19. PHENOLICS• Examples: Benzyl-4- chlorophenol, Amyl phenol, Phenyl phenol• Advantages and disadvantages: good general purpose disinfectants, not readily inactivated• by organic matter, active against wide range of organisms (including mycobacterium), but not sporicidal.DR.T.V.RAO MD 19
  • 20. PHENOL AS DISINFECTANT• Phenolic disinfectants are effective against bacteria (especially gram positive bacteria) and enveloped viruses. They are not effective against nonenvelopedd viruses and spores. These disinfectants maintain their activity in the presence of organic material. DR.T.V.RAO MD 20
  • 21. PHENOL AS DISINFECTANT • They are not effective against nonenvelopedd viruses and spores. These disinfectants maintain their activity in the presence of organic material. This class of compounds is used for decontamination of the hospital environment, including laboratory surfaces, and noncritical medical items DR.T.V.RAO MD 21
  • 22. PHENOL AS DISINFECTANT• Phenolics are not recommended for semi critical items because of the lack of validated efficacy data for many of the available formulations and because the residual disinfectant on porous materials may cause tissue irritation even when thoroughly rinsed. DR.T.V.RAO MD 22
  • 23. IODINE AND IODOPHOR DISINFECTANTS• These compounds have been incorporated in time release formulations and in soaps (surgical scrubs). Simple iodine tinctures (dissolved in alcohol) have limited cleaning ability. These compounds are bactericidal, sporicidal, virucidal and fungicidal but require a prolonged contact time. DR.T.V.RAO MD 23
  • 24. IODINE AND IODOPHOR DISINFECTANTS • Besides their use as an antiseptic, Iodophor have been used for the disinfection of blood culture bottles and medical equipment such as hydrotherapy tanks, thermometers, and endoscopes DR.T.V.RAO MD 24
  • 25. IODINE AND IODOPHOR DISINFECTANTS• The disinfective ability of iodine, like chlorine, is neutralized in the presence of organic material and hence frequent applications are needed for thorough disinfection. Iodine tinctures can be very irritating to tissues, can stain fabric and be corrosive. DR.T.V.RAO MD 25
  • 26. ALCOHOLS• “Alcohol" refers to two water-soluble chemicals: ethyl alcohol and isopropyl alcohol. These alcohols are rapidly bactericidal rather than bacteriostatic against vegetative forms of bacteria (Gram + and Gram -); they also are tuberculocidal, fungicidal, and virucidal against enveloped viruses. Alcohols are not effective against bacterial spores and have limited effectiveness against nonenveloped viruses DR.T.V.RAO MD 26
  • 27. ALCOHOLS• Their cidal activity drops sharply when diluted below 50% concentration and the optimum bactericidal concentration is in the range of 60-90% solutions in water (volume/volume). The antimicrobial activity of alcohols can be attributed to their ability to denature proteins. DR.T.V.RAO MD 27
  • 28. ALCOHOLS • Higher concentrations are less effective as the action of denaturing proteins is inhibited without the presence of waterDR.T.V.RAO MD 28
  • 29. ALCOHOLS• Alcohols are commonly used topical antiseptics. They are also used to disinfect the surface of medical equipment. Alcohols require time to work and they may not penetrate organic material. DR.T.V.RAO MD 29
  • 30. ALCOHOLS • They also evaporate rapidly which makes extended exposure time difficult to achieve unless the items are immersed. Alcohol irritates tissues. They are generally too expensive for general use as a surface disinfectantDR.T.V.RAO MD 30
  • 31. GAINING IMPORTANCE IN HAND WASHING WITH ALCOHOLS• The use of either ethyl alcohol or isopropyl alcohol in a 60-90% solution has recently gained wide acceptance in health care settings as hand antiseptics. They can be used as a reasonable substitute for handwashing as long as hands are not visibly s oiled DR.T.V.RAO MD 31
  • 32. HYPOCHLORITES• They have a broad spectrum of antimicrobial activity, are unaffected by water hardness, are inexpensive and fast acting, and have a low incidence of serious toxicity DR.T.V.RAO MD 32
  • 33. DR.T.V.RAO MD 33
  • 34. HYPOCHLORITES • Other disadvantages of hypochlorites include corrosiveness to metals in high concentrations (>500 ppm), inactivation by organic matter, discoloring or “bleaching” of fabrics, and release of toxic chlorine gas when mixed with ammonia or acid. DR.T.V.RAO MD 34
  • 35. HYPOCHLORITES• Hypochlorites can eliminate both enveloped and nonenveloped viruses if used in correct dilution and contact time. They are also is effective against fungi, bacteria, and algae but not spores. Household bleach is typically diluted using 1:50 with water (1000ppm) for surface disinfection. Bleach solutions have been recommended for use in both hospitals and the community as disinfecting solutions. DR.T.V.RAO MD 35
  • 36. HYPOCHLORITES MOST RECOMMENDED IN• They are included in most recommendation for decontamination of hepatitis and AIDS viruses DR.T.V.RAO MD 36
  • 37. HYPOCHLORITES • Hypochlorites 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. DR.T.V.RAO MD 37
  • 38. HYPOCHLORITES• Chlorinated drinking water should not exceed 6 to 10 ppm of free chlorine with the lower value being in continuous flow or low volume reservoir systems. DR.T.V.RAO MD 38
  • 39. HIGH LEVEL DISINFECTANTSDR.T.V.RAO MD 39
  • 40. HYDROGEN PEROXIDE• Peroxides such as hydrogen peroxide are often used as antiseptics to clean wounds. The activity of peroxides is greatest against anaerobic bacteria. 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. DR.T.V.RAO MD 40
  • 41. HYDROGEN PEROXIDE• Stabilized hydrogen peroxides can be used to disinfect environmental surfaces. The literature contains several accounts of the properties, germicidal effectiveness, and potential uses for stabilized hydrogen peroxide in the hospital setting DR.T.V.RAO MD 41
  • 42. FORMALDEHYDE • Gluteraldehydes are very potent disinfectants, which can be highly toxic. Use them only as a last resort and then under trained supervision in a well-ventilated setting and with appropriate personal protective equipment. DR.T.V.RAO MD 42
  • 43. FORMALDEHYDE• Formaldehyde is used as a disinfectant and sterilant both in the liquid and gaseous states. Formaldehyde is sold and used principally as a water-based solution called formalin, which is 37% formaldehyde by weight. The aqueous solution is bactericidal, tuberculocidal, fungicidal, virucidal and sporicidal DR.T.V.RAO MD 43
  • 44. FORMALDEHYDE • Formaldehyde should be handled in the workplace as a potential carcinogen with an employee exposure standard that limits an 8 hour time-weighted average exposure to a concentration of 0.75 ppm. For this reason, employees should have limited direct contact with formaldehyde and these considerations limit its role in sterilization and disinfection processes DR.T.V.RAO MD 44
  • 45. GLUTARALDEHYDE• Aldehydes have a wide germicidal spectrum. Gluteraldehydes are bactericidal, virucidal, fungicidal, sporicidal and parasiticidal. They are used as a disinfectant or sterilant in both liquid and gaseous forms. They have moderate residual activity and are effective in the presence of limited amounts of organic material DR.T.V.RAO MD 45
  • 46. ETHYLENE OXIDE• Ethylene oxide, also called oxirane, is the organic compound with the formula C 2H4O. It is a cyclic ether. This means that it is composed of two alkyl groups attached to an oxygen atom in a cyclic shape (circular). This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered ring consisting of two carbon and one oxygen atom.DR.T.V.RAO MD 46
  • 47. ETHYLENE OXIDE ADVANTAGES• Highly effective against most microbes• Highly diffusive• Compatible with a wide variety of materials in devices and packaging
  • 48. ETHYLENE OXIDE DISADVANTAGES• Complex process• Longer turn-around times • BI Testing • Residual dissipation• Safety concerns • Flammable • Explosive• OSHA concerns • Carcinogen• EPA concerns • Emissions
  • 49. ORTHO-PHTHALALDEHYDE• Ortho-phthalaldehyde (OPA) is a chemical sterilant similar to Gluteraldehydes with similar antimicrobial activity. OPA has several potential advantages compared to Gluteraldehydes. It has excellent stability over a wide pH range (pH 3-9), is not a known irritant to the eyes and nasal passages, does not require exposure monitoring, has a barely perceptible odor, and requires no activation. OPA, like Gluteraldehydes, has excellent material compatibilityDR.T.V.RAO MD 49
  • 50. ORTHO-PHTHALALDEHYDE• A potential disadvantage of OPA is that it stains proteins gray (including unprotected skin) and thus must be handled with caution. However, skin staining would indicate improper handling that requires additional training and/or personal protective equipment (PPE) (gloves, eye and mouth protection, fluid-resistant gowns).DR.T.V.RAO MD 50
  • 51. PER ACETIC ACID• Per acetic, or peroxyacetic, acid is characterized by a very rapid action against all microorganisms. A special advantage of per acetic acid is it has no harmful decomposition products (i.e., acetic acid, water, oxygen, hydrogen peroxide) and leaves no residue. It remains effective in the presence of organic matter and is sporicidal even at low temperat uresDR.T.V.RAO MD 51
  • 52. PER ACETIC ACID• It is used in automated machines to chemically sterilize medical, surgical, and dental instruments (e.g., endoscopes, arthroscopies). DR.T.V.RAO MD 52
  • 53. PER ACETIC ACID AND HYDROGEN PEROXIDE• Two chemical sterilants are available that contain per acetic acid plus hydrogen peroxide (0.08 per acetic acid plus 1.0% hydrogen peroxide [no longer marketed], 0.23% per acetic acid plus 7.35% hydrogen peroxide). The bactericidal properties of per acetic acid and hydrogen peroxide have been established.DR.T.V.RAO MD 53
  • 54. PER ACETIC ACID AND HYDROGEN PEROXIDE USEFUL IN HEM DIALYZERS• Findings demonstrated that this product inactivated all microorganisms with the exception of bacterial spores within 20 minutes. The combination of per acetic acid and hydrogen peroxide has been used for disinfecting hem dialyzers. DR.T.V.RAO MD 54
  • 55. QUATERNARY AMMONIUM COMPOUNDS• The quaternaries are good cleaning agents but high water hardness and materials such as cotton and gauze pads may make them less microbicidal because these materials absorb the active ingredients. As with several other disinfectants (e.g., phenolic, Iodophor) gram-negative bacteria have been found to survive or grow in these preparationsDR.T.V.RAO MD 55
  • 56. QUATERNARY AMMONIUM COMPOUNDS• They are not effective against non-enveloped viruses, fungi and bacterial spores. QA disinfectants carry a very strong positive charge that makes good contact with negatively charged surfaces. This characteristic makes most very good cleaning agents. QA compounds are generally low in toxicity, but prolonged contact can be irritating. The quaternaries are commonly used in ordinary environmental sanitation of noncritical surfaces such as floors, furniture, and walls DR.T.V.RAO MD 56
  • 57. GAS PLASMA STERILIZATIONDR.T.V.RAO MD 57
  • 58. WHAT IS GAS PLASMA• Plasma is a fourth state of matter which is distinguishable from liquid, solid, or gas. In nature, plasma is widespread in outer space.• Gas plasma generated in an enclosed chamber under deep vacuum using Radio frequency or Microwave emery to excite gas molecules are produced charged particles• Can be used for hand sterilizationDR.T.V.RAO MD 58
  • 59. HOW GAS PLASMA WORKS.• Many particles are in the form of free radicals• A free radical is an Atom with an unpaired electron and is a highly reactive species• The mechanism of action of this device is the production of free radicals within a plasma field that are capable of interacting with essential cell components, ie is enzymes and nucleic acids. And thereby disrupt the metabolism of microorganisms. DR.T.V.RAO MD 59
  • 60. GAS PLASMA - STERILIZATION• Plasma sterilization operates differently because of its specific active agents, which are ultraviolet (UV) photons and radicals (atoms or assembly of atoms with unpaired electrons, therefore chemically reactive, e.g., O and OH, respectively DR.T.V.RAO MD 60
  • 61. BASIC MECHANISMS OF PLASMA STERILIZATION• Destruction by UV irradiation of the genetic material of the microorganism; this is a statistical process requiring a sufficient number of lesions of the DNA strands.• Erosion of the microorganism, atom by atom, through intrinsic photo desorptionDR.T.V.RAO MD 61
  • 62. ADVANTAGE OF THE PLASMA METHOD• An advantage of the plasma method is the possibility, under appropriate conditions, of achieving such a process at relatively low temperatures (≤50 °C), preserving the integrity of polymer-based instruments, which cannot be subjected to autoclaves and ovens Furthermore, plasma sterilization is safe, both for the operator and the patient, in contrast to EtO.DR.T.V.RAO MD 62
  • 63. HYDROGEN PEROXIDE STERILIZATION OFFERS FAST CYCLE TIMES• Benefits of gas plasma (vaporized hydrogen peroxide) sterilization are fast cycle times, the absence of toxic residuals, and a low-moisture environment not exceeding 50ºC,DR.T.V.RAO MD 63
  • 64. NEW CDC GUIDELINES FACTORS RELATED TO INFECTION RISK• Endoscope contamination accounts for more health care related infections than any other medical instrument and is responsible for consequences ranging from bacterial colonization to death. DR.T.V.RAO MD 64
  • 65. DISINFECTION AND STERILIZATION ARE AFFECTED BY• Initial cleaning of the device• Physical complexity of the device Biofilms and microbial load• Microbe type and quantity• HLD exposure time and concentrationDR.T.V.RAO MD 65
  • 66. BIOFILMS INTERFERE IN EFFECTIVE ANTIMICROBIAL ACTION • “Biofilms are microbial communities that are tightly attached to surfaces and cannot be easily removed...Bacteria within biofilms are up to 1,000 times more resistant to antimicrobials than are the same bacteria in suspension DR.T.V.RAO MD 66
  • 67. BIOFILMS INTERFERE IN EFFECTIVE ANTIMICROBIAL ACTION• “One multistate investigation found that 23.9% of the bacterial cultures from the internal channels of 71 gastrointestinal endoscopes grew ≥100,000 colonies of bacteria after completion of all disinfection and sterilization procedures DR.T.V.RAO MD 67
  • 68. GUIDELINE EXCERPTS INFECTION RISKS• “Multiple studies in many countries have documented lack of compliance with established guidelines for disinfection and sterilization.• Failure to comply with scientifically-based guidelines has led to numerous outbreaks. DR.T.V.RAO MD 68
  • 69. 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 waste and• Taking care of yourself (e.g. immunization) DR.T.V.RAO MD 69
  • 70. HAN YET – NO SUBSTITUTE FOR HAND WASHING :Immediately on arrival at workBefore and after examining each clientAfter touching anything that might be contaminatedAfter handling specimensBefore putting on gloves for clinical proceduresAfter removing glovesAfter using the toilet or latrineBefore leaving workDR.T.V.RAO MD 70
  • 71. • Programme Created by Dr.T.V.Rao MD for Medical and Paramedical professionals in the Developing World • Email • doctortvrao@gmail.comDR.T.V.RAO MD 71

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