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![DISINFECTION AND STERILIZATION
EH Spaulding believed that how an object will be
disinfected depended on the object’s intended use.
CRITICAL - objects which enter normally sterile tissue or the
vascular system or through which blood flows should be
sterile.
SEMICRITICAL - objects that touch mucous membranes or
skin that is not intact require a disinfection process (high-
level disinfection[HLD]) that kills all microorganisms but
high numbers of bacterial spores.
NONCRITICAL -objects that touch only intact skin require
low-level disinfection.
DR.T.V.RAO MD 13](https://image.slidesharecdn.com/sterilizationanddisinfectioninhealthcare-231113022544-3ac18d6f/75/Sterilization-and-disinfection-in-health-care-pptx-13-2048.jpg)
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Sterilization and disinfection in health care.pptx
This document discusses the history and methods of sterilization and disinfection. It begins with a brief history of sterilization dating back to the invention of the autoclave in 1862. It then covers terminology related to sterilization and discusses various sterilization methods including physical methods like heat, filtration, and irradiation as well as chemical methods. Factors that influence the efficacy of sterilization methods are also examined. The document provides an overview of the development and principles of sterilization.
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Sterilization and disinfection in health care.pptx
- 1. Dr.T.V.Rao MD STERILIZATION ANDDISINFECTION AN UPDATE DR.T.V.RAO MD 1
- 2. HISTORY • 1862 Inventionof the Autoclave • 1880 The first indicator : a potato • 1906 Creation of the FDA • 1925 Waxy pellets that melt at 121oC • 1932 (ATI) CI with lead sulphite passes from black to white • 1940 (ATI) CI Chromium TriChloride passes from purple to green DR.T.V.RAO MD 2
- 3. HISTORY (CONT) • 1960-70Development of the Dvalue concept using heat resistant spores for sterilisation + Fvalue + Zvalue • 1965 Proposal by Sweden of the SAL for a definition of sterility • 1979 Proposal by Canada of a legal definition of sterility DR.T.V.RAO MD 3
- 4. 4 TERMINOLOGY IN STERILIZATION •Sterilization – a process that destroys all viable microbes, including viruses and endospores; microbicidal • Disinfection – a process to destroy vegetative pathogens, not endospores; inanimate objects • Antiseptic – disinfectants applied directly to exposed body surfaces • Sanitization – any cleansing technique that mechanically removes microbes DR.T.V.RAO MD
- 5. 5 TERMINOLOGY IN STERILIZATION •Degermation – mechanically removing microbes form surface (skin) such as surgical hand scrubbing, or wiping skin with alcohol prior to venipuncture • Sepsis – bacterial contamination • Asepsis – absence of significant contamination • Bactericidal (microbicidal) - -cidal means kill • Bacteriostatic (micro biostatic) - -static means inhibition of growth and multiplication DR.T.V.RAO MD
- 6. AIM OF STERILIZATION- ASEPSIS Asepsis is the practice to reduce or eliminate contaminants (such as bacteria, viruses, fungi, and parasites) from entering the operative field in surgery or medicine to prevent infection. Ideally, a field is "sterile" — free of contaminants — a situation that is difficult to attain. However, the goal is elimination of infection, not sterility. • http://en.wikipedia.org/wiki/Asepsis DR.T.V.RAO MD 6
- 7. HOW STERILIZATION WORKS •Cell wall maintains integrity of cell • When disrupted, cannot prevent cell from bursting due to osmotic effects • Cytoplasmic membrane contains cytoplasm and controls passage of chemicals into and out of cell • When damaged, cellular contents leak out • Viral envelope responsible for attachment of virus to target cell • Damage to envelope interrupts viral replication • So…non enveloped viruses have greater tolerance of harsh conditions DR.T.V.RAO MD 7
- 8. METHODS • Physical • Heat •Filtration • Irradiation • Quarantine • Chemical • Choice of method depends on practical issues such as ease of use or material compatibility • Proctoscope need not be as free of contamination as an artificial heart valve • Cleaning of objects needed before attempt at sterilization DR.T.V.RAO MD 8
- 9. • Strength ofthe killing agent • Time that the agent has to act • Temperature of environment • rate of microbe death doubles with every 10˚C rise in temp. • Type of microbe • Environment around the area to be decontaminated • Number of microbes to be killed FACTORS INFLUENCING ABILITY TO KILL MICROBES DR.T.V.RAO MD 9
- 10. “IDEAL” STERILIZATION METHOD •Highly efficacious • Rapidly active • Strong penetrability • Materials compatibility • Non-toxic • Organic material resistance • Adaptability • Monitoring capability • Cost-effective Schneider PM. Tappi J. 1994;77:115-119 DR.T.V.RAO MD 10
- 11. FACTORS THAT INFLUENCEEFFICACY OF DISINFECTION/STERILIZATION Contact time Physico-chemical environment (e.g. pH) 3 Presence of organic material 4 Temperature 5 Type of microorganism 6 Number of microorganisms 7 Material composition DR.T.V.RAO MD 11
- 12. burning method(incineration) flowingsteam disinfection hot air drying method(烤箱) boiling water disinfection DR.T.V.RAO MD 12
- 13. DISINFECTION AND STERILIZATION EHSpaulding believed that how an object will be disinfected depended on the object’s intended use. CRITICAL - objects which enter normally sterile tissue or the vascular system or through which blood flows should be sterile. SEMICRITICAL - objects that touch mucous membranes or skin that is not intact require a disinfection process (high- level disinfection[HLD]) that kills all microorganisms but high numbers of bacterial spores. NONCRITICAL -objects that touch only intact skin require low-level disinfection. DR.T.V.RAO MD 13
- 14. Endospores Mycobacteria Fungal Spores Small Non-envelopedviruses (polio, rotavirus, rabies) Vegetative Fungal Cells Enveloped Viruses (Herpes, Hepatitis B, Hepatitis C, HIV) Vegetative Bacteria Most Resistant Least Resistant DR.T.V.RAO MD 14
- 15. SPORICIDAL AGENTS • Glutaraldehyde •Formaldehyde • Other aldehydes • Chlorine-releasing agents • Iodine and iodophores • Peroxygens • Ethylene oxide • P-Propiolactone • A. D. RUSSELL, 1999. Bacterial Spores and Chemical Sporicidal Agents. CLINICAL MICROBIOLOGY REVIEWS Vol. 3, No. 2 p. 99-119 . DR.T.V.RAO MD 15
- 16.
- 17. Physical Methods ofMicrobial Control: Heat: Kills microorganisms by denaturing their enzymes and other proteins. Heat resistance varies widely among microbes. Thermal Death Point (TDP): Lowest temperature at which all of the microbes in a liquid suspension will be killed in ten minutes. Thermal Death Time (TDT): Minimal length of time in which all bacteria will be killed at a given temperature. Decimal Reduction Time (DRT): Time in minutes at which 90% of bacteria at a given temperature will be killed. Used in canning industry. DR.T.V.RAO MD 17
- 18. • 100 oCat 1 ATM • 121 oC at 2 ATM (1 barr) • 132 oC at 3 ATM (2 barr) • 80 oC at 0.5 ATM (Mont Blanc) • 70 oC at 0.35 ATM (Mont Everest) • 40 oC at 0.02 ATM (Mechanical vacuum) BOILING TEMPERATURE IS LINKED TO PRESSURE DR.T.V.RAO MD 18
- 19. BOILING • Kills vegetativecells of bacteria and fungi, protozoan trophozoites, and most viruses within 10 minutes at sea level • Temperature cannot exceed 100ºC at sea level; steam carries some heat away • Boiling time is critical • Water boils at lower temperatures at higher elevations; requires longer boiling time • Endospores, protozoan cysts, and some viruses can survive boiling DR.T.V.RAO MD 19
- 20. PHYSICAL METHODS: HEAT •Pasteurisation • First used with milk: 72°C for 20 seconds • Heating to 80°C for 1 minute will kill most vegetative organisms • Examples: bed-pan washer, proctoscope • Dry heat (hot air oven) • used on waxes, oils (wet heat usually preferred) • Incineration • the ultimate sterilization • used for disposal of hospital waste • Wet heat • Boiling • limited use as spores may be resistant, boilers may be misused • Low temperature steam disinfection (75°C for 30 mins) • Used for e.g. ventilator tubing • Autoclaving • High-temperature steam plus pressure (same principle as pressure cooker) DR.T.V.RAO MD 20
- 21. MOIST HEAT • Usedto disinfect, sanitize, and sterilize • Kills by denaturing proteins and destroying cytoplasmic membranes • More effective than dry heat; water better conductor of heat than air • Methods of microbial control using moist heat • Boiling • Autoclaving • Pasteurization • Ultrahigh-Temperature Sterilization DR.T.V.RAO MD 21
- 22. MOIST HEAT • Pasteurization Definition:a process in which fluids are heated at temperatures below boiling point to kill pathogenic microorganisms in the vegetative state without altering the fluid’s palatability. Conditions: 62℃, 30min or 71.7℃, 15sec Significance: kills vegetative pathogens Applications: milk, beer DR.T.V.RAO MD 22
- 23. AUTOCLAVING • Pressure appliedto boiling water prevents steam from escaping • Boiling temperature increases as pressure increases • Autoclave conditions – 121ºC, 15 psi, 15 minutes DR.T.V.RAO MD 23
- 24. STRUCTURAL DIAGRAM OFAUTOCLAVES DR.T.V.RAO MD 24
- 25. STEAM QUALITY ISIMPORTANT Saturated steam 98% steam, 2% water vapor Dry steam Superheated Wet steam Supersaturated DR.T.V.RAO MD 25
- 26.
- 27. Other Physical Methodsof Microbial Control: Filtration: Removal of microbes by passage of a liquid or gas through a screen like material with small pores. Used to sterilize heat sensitive materials like vaccines, enzymes, antibiotics, and some culture media. High Efficiency Particulate Air Filters (HEPA): Used in operating rooms and burn units to remove bacteria from air. Membrane Filters: Uniform pore size. Used in industry and research. Different sizes: 0.22 and 0.45um Pores: Used to filter most bacteria. Don’t retain spirochetes, mycoplasmas and viruses. 0.01 um Pores: Retain all viruses and some large proteins. DR.T.V.RAO MD 27
- 28. Physical Methods ofMicrobial Control: Radiation: Three types of radiation kill microbes: 1. Ionizing Radiation: Gamma rays, X rays, electron beams, or higher energy rays. Have short wavelengths (less than 1 nanometer). Dislodge electrons from atoms and form ions. Cause mutations in DNA and produce peroxides. Used to sterilize pharmaceuticals and disposable medical supplies. Food industry is interested in using ionizing radiation. Disadvantages: Penetrates human tissues. May cause genetic mutations in humans. DR.T.V.RAO MD 28
- 29.
- 30. Physical Methods ofMicrobial Control: Radiation: Three types of radiation kill microbes: Microwave Radiation: Wavelength ranges from 1 millimeter to 1 meter. Heat is absorbed by water molecules. May kill vegetative cells in moist foods. Bacterial endospores, which do not contain water, are not damaged by microwave radiation. Solid foods are unevenly penetrated by microwaves. Trichinosis outbreaks have been associated with pork cooked in microwaves. DR.T.V.RAO MD 30
- 31. • Mechanism mechanically removes microorganisms •Application sterilize materials likely to be damaged by heat FILTRATION DR.T.V.RAO MD 31
- 32.
- 33. HOW COMPLEX AENDOSCOPE TO STERILIZE DR.T.V.RAO MD 33
- 34.
- 35. • Major Categories •Phenols • Alcohols • Halogens • Oxidizing agents • Surfactants • Heavy Metals • Aldehydes • Gaseous Agents • Antimicrobics CHEMICAL METHODS OF MICROBIAL CONTROL DR.T.V.RAO MD 35
- 36. FACTORS INFLUENCING ANTIMICROBIAL ACTIVITY •the concentration and kind of an agent used • the length of exposure to the agent • the temperature at which the agent is used • the number of microorganisms present • the kinds of microorganisms present • the nature of the material bearing the microorganism DR.T.V.RAO MD 36
- 37. PHENOL AND PHENOLICS •Intermediate- to low-level disinfectants • Denature proteins and disrupt cell membranes • Effective in presence of organic matter and remain active for prolonged time • Commonly used in health care settings, labs, and homes (Lysol, triclosan) • Have disagreeable odor and possible side effects DR.T.V.RAO MD 37
- 38. • Intermediate-level disinfectants • Denatureproteins and disrupt cytoplasmic membranes • Evaporate rapidly – both advantageous and disadvantageous • Swabbing of skin with 70% ethanol prior to injection ALCOHOLS DR.T.V.RAO MD 38
- 39. ISOPROPYL ALCOHOL (70%) ISOPROPYLALCOHOL (70%) • Powerful disinfectant and antiseptic • Mode of action: denatures proteins, dissolves lipids and can lead to cell membrane disintegration • Effectively kills bacteria and fungi • But does not inactivate spores! DR.T.V.RAO MD 39
- 40. • Intermediate-level antimicrobial chemicals •Believed that they damage enzymes via oxidation or by denaturing them • Iodine tablets, iodophores (Betadine®), chlorine treatment of drinking water, bleach, chloramines in wound dressings, and bromine disinfection of hot tubs HALOGENS DR.T.V.RAO MD 40
- 41. • Peroxides, ozone,and per acetic acid kill by oxidation of microbial enzymes • High-level disinfectants and antiseptics • Hydrogen peroxide can disinfect and sterilize surfaces of objects • Ozone treatment of drinking water • Per acetic acid – effective sporocide used to sterilize equipment OXIDIZING AGENTS DR.T.V.RAO MD 41
- 42. SURFACTANTS • Surface active”chemicals that reduce surface tension of solvents to make them more effective at dissolving solutes • Soaps and detergents • Soaps have hydrophilic and hydrophobic ends; good degerming agents but not antimicrobial • Detergents are positively charged organic surfactants • Quats – colorless, tasteless, harmless to humans, and antimicrobial; ideal for many medical and industrial application • Low-level disinfectants DR.T.V.RAO MD 42
- 43. HEAVY METALS • Ionsare antimicrobial because they alter the 3-D shape of proteins, inhibiting or eliminating their function • Low-level bacteriostatic and fungistatic agents • 1% silver nitrate to prevent blindness caused by N. gonorrhoeae • Thimerosal (mercury-containing compound) used to preserve vaccines • Copper controls algal growth in reservoirs, fish tanks, swimming pools, and water storage tanks; interferes with chlorophyll DR.T.V.RAO MD 43
- 44. • Denature proteinsand inactivate nucleic acids • Glutaraldehyde both disinfects (short exposure) and sterilizes (long exposure) • Formalin used in embalming and disinfection of rooms and instruments ALDEHYDES DR.T.V.RAO MD 44
- 45. PROBLEMS WITH STERILITY •Lack of understanding of risk/process • physicians introducing new products (borrowed, samples) • Multidose vials • What is sterile vs not • Lack of understanding of components of process • MDs, technologists have less training than nurses (anaesthesiology, imaging, urology) DR.T.V.RAO MD 45
- 46. GASEOUS AGENTS • Ethyleneoxide, propylene oxide, and beta- propiolactone used in closed chambers to sterilize items • Denature proteins and DNA by cross-linking functional groups • Used in hospitals and dental offices • Can be hazardous to people, often highly explosive, extremely poisonous, and are potentially carcinogenic DR.T.V.RAO MD 46
- 47. • Yes. • Plasmasare currently employed in many industries to accomplish both highly effective, and delicate sterilization. • Not future technology! Plasmas are used today! • But, how do they work? CURRENT STERILIZATION MEANS: PLASMAS? DR.T.V.RAO MD 47
- 48. PLASMA STERILIZATION • Aplasma is a quasi-neutral collection of electrons, positive ions, and neutrals capable of collective behavior • Positive ions = free radicals • Plasma sterilization operates synergistically via three mechanisms: • Free radicals interactions • UV/VUV radioactive effects • Volatilization • Dead microorganisms = sterilization DR.T.V.RAO MD 48
- 49. DISADVANTAGES OF PLASMA STERILIZATION •Weak penetrating power of the plasma species. Complications arise in: • Presence of organic residue • Packaging material • Complex geometries • Bulk sterilization of many devices • Solutions: Introduce preferentially targeting UV/VUV radiation of proper wavelength DR.T.V.RAO MD 49
- 50. CAN ENVIRONMENTAL CLEANINGREDUCE MRSA TRANSMISSION? • Setting: ward with endemic MRSA, and widespread environmental contamination • Before-after study • Cleaning time increased by 57 hours per week • Responsibility for routine cleaning of shared equipment delineated • In 6 months post-intervention, number of MRSA acquisitions decreased fro 30 to 3 per 6 months Rampling A JHI 2001;49:109 DR.T.V.RAO MD 50
- 51. • Audit andfeedback • New technology • Hydrogen peroxide vapour/gas • UV room decontamination? antibacterial surface coatings? IMPROVING NON-CRITICAL ITEM/ENVIRONMENT DISINFECTION Otter ICHE 2009;30(6):574-7 DR.T.V.RAO MD 51
- 52. THE PROBLEM OFCJD AND TSES • Creutzfeldt-Jakob syndrome and other transmissible spongiform encephalopathies caused by highly resistant proteinaceous particles, prions • can survive 3 years of environmental exposure and are unusually resistant to conventional decontamination methods • Iatrogenic CJD documented in three circumstances • use of contaminated medical equipment (2 cases) • use of extracted pituitary hormones (> 130 cases) • implantation of contaminated grafts from humans (cornea, 3 cases; dura mater, > 110 cases) DR.T.V.RAO MD 52
- 53. INACTIVATION OF PRIONS •Steam sterilization with NaOH • Alkaline cleaner (pH 2.2, 1 hr 23°C) • Copper plus peracetic acid • Vapourized hydrogen peroxide (Sterrad NX) Yan ICHE 2004;25:280, Fichet Lancet 2004;384:251, Baier JHI 2004;57:80, Lemmer J Gen Virol 2004;85:3805; Roger-Kreuz, ICHE 2009;30(8):769-77 Lehman Hosp Infect. 2009;72(4):342-50; DR.T.V.RAO MD 53
- 54. WHAT IS ANINDICATOR OR STERILISATION CONTROL ? • On paper • Self -contained • Sealed ampulla (spores + broth) • Spores suspension • Tube witness (point of fusion) It is a device conceived to verify if the process operated as expected DR.T.V.RAO MD 54
- 55. VALIDATION OF BIOLOGICAL INDICATORS •The reality : • We do not use the most resistant organisms • The predictive behaviour is generally linear only for one process • Manufacturers seldom use more “practical” strains (read : “less linear” strains for more economical, inoffensive, self resistance and stability) • There is no such thing as a “universal biological indicator” • The choice of any particular strain is therefore a manner of arbitrary choice DR.T.V.RAO MD 55
- 56.
- 57. QUANTIFYING STERILIZATION EFFICACY • • i.e. Timerequired for the microbial population to be reduced to one decimal DR.T.V.RAO MD 57
- 58. • Little evidencethat extensive use of products containing antiseptic and disinfecting chemicals adds to human or animal health • The use of such products promotes the development of resistant microbes EXCESSIVE USE OF CHEMICALS CAN CREATE RESISTANT MICROBES ??? DR.T.V.RAO MD 58
- 59. • Avoid cleanroomswhen ill • Frequent bathing and shampooing • Avoid cosmetics such as face powder, hair sprays, perfumes and aftershave • Clothing should be clean, nonfrayed and nonlinting • Avoid smoking STERILIZATION IS SUCCESSFUL WITH PERSONNEL: HYGIENE DR.T.V.RAO MD 59
- 60. WHO / WHATIS IMPORTANT IN PREVENTION OF INFECTIONS
- 61. WE ARE ALLIMPORTANT
- 62. DR.T.V.RAO MD 62 •Programme created by Dr.T.V.Rao MD for Medical and Paramedical Professionals in the Developing World • Email • doctortvrao@gmail.com