Sterilization, Disinfection, and Antisepsis PDF

STERILIZATION, DISINFECTION, AND ANTISEPSIS Asst. Prof. Ayhan MEHMETOĞLU [email protected] 1 Learning Outcomes Student should be able to define sterilization and disinfection and antisepsis. Understand methods of sterilization and disinfection: Physical methods....

STERILIZATION, DISINFECTION, AND ANTISEPSIS Asst. Prof. Ayhan MEHMETOĞLU [email protected] 1 Learning Outcomes Student should be able to define sterilization and disinfection and antisepsis. Understand methods of sterilization and disinfection: Physical methods. Chemical methods. Mechanical removal methods. Explain the role of sterilization and disinfection in diseases control. 2  3 INTRODUCTION Microorganisms are the agents of contamination, infection, and decay. Hence it becomes necessary to remove them from materials and areas. Early civilization practiced salting, smoking, pickling and exposure to sunlight. http://images6.fanpop.com/image/photos/37400000/Anubis-Attending-to- the-Pharaoh-ancient-egypt-37472350-271-210.jpg  In mid 1800s Lister developed Aseptic techniques to prevent contamination of surgical wounds. Aseptic Prior to this development: Nosocomial infections caused techniques death in 10% of surgeries. Up to 25% mothers delivering in hospitals died due to infection. 4 Methods of microbial growth control Alternation of membrane permeability Damage to proteins Damage to nucleic acids 5  DEFINITION OF STERILIZATION The process of freeing an article from microorganisms including their spores.  Sterilization is the killing or removal of all microorganisms, including bacterial spores, Sterilization which are highly resistant. Sterilization is usually carried out by autoclaving, which consists of exposure to steam at 121°C under a pressure of 15 lb/in2 for 15 minutes. Surgical instruments that can be damaged by moist heat are usually sterilized by exposure to ethylene oxide gas, and most intravenous solutions are sterilized by filtration. 7  Disinfection is the killing of many, but not all, microorganisms. Disinfection For adequate disinfection, pathogens must be killed, but some organisms and bacterial spores may survive. Disinfectants: corrosive phenol-containing, Antisepsis: less toxic materials such as ethanol and iodine, which can be used on skin surfaces. Chemicals used to kill microorganisms on the surface of skin and mucous membranes are called antiseptics. 9 Don’t forget Sterilization – a process that destroys all viable Disinfection – a process to destroy vegetative microbes, including pathogens, not viruses and endospores; endospores; inanimate microbicidal objects Antiseptic – Sanitization – any disinfectants applied cleansing technique that directly to exposed body mechanically removes surfaces microbes 11 Terminology 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 13 Terminology Bacteriostatic Bactericide: Sporicidal: Agent: An agent that An agent that An agent that inhibits the kills bacteria. kills spores. growth of Most do not kill bacteria but does Endospores. not necessarily kill them. 14  Asepsis is the practice to reduce or eliminate contaminants (such as bacteria, viruses, fungi, and AIM OF parasites) from entering the operative field in surgery or STERILIZATION - medicine to prevent infection. ASEPSIS Ideally, a field is "sterile" — free of contaminants — a situation that is difficult to attain. However, the goal is elimination of infection, not sterility. 16  Physical Agents Methods of Microbial Control Chemical Agents Sterilization Methods Mechanical Removal Methods 17  Physical Agents Heat Radiation Dry Moist Ionizing Non-Ionizing X Ray, Steam Under Incineration Cathode, UV Pressure Gamma Boiling Water/Hot Dry Oven Water Pasteurization 18  Chemical Agent Gas Liquids Sterilization Disinfection Animate Inanimate Chemotherapy Antiseptics Sterilization Disinfection 19 Mechanical Removal Methods Filtration Air Liquids 20 Sterilization By Dry Heat Kills by oxidation effects The oven utilizes dry heat to sterilize articles Operated between 50oC to 250/300oC. A holding period of 160oC for 2 hr is desirable. There is a thermostat controlling the temperature. Double walled insulation keeps the heat in and conserves energy, 21  hours Uses hours hour To sterilize Forceps, Scissors, Scalpels, Swabs. Pharmaceuticals products like Liquid paraffin, dusting powder, fats and grease. 22 FLAMING/INCINERATION Inoculation loop or Wire, the tip of Forceps and spatulas are held in a Bunsen flame till they are red hot. This is an excellent method of destroying materials such as contaminated cloth, animal carcasses and pathological materials. 23 MOIST HEAT STERILIZATION Kills microorganisms by coagulating their proteins 24 MOIST HEAT STERILIZATION Temp below 100oC: “Pasteurisation”, Inspissator. Temperature at 100oC: Boiling. Steam at atmospheric pressure: Koch/Arnold’s steamer. Steam under pressure: Autoclave. 25  Pasteurization Process of killing of pathogens in the milk but does not sterilize it. Milk is heated at 63oC for 30 mins. (HOLDER METHOD) At 72oC for 15-20 Sec. Rapid cooling to 13oC (FLASH PROCESS) 26 HOT WATER BATH To inactivate non sporing bacteria for the preparation of vaccines - Special vaccine bath at 60oC for one hour is used Serum or body fluids containing coagulable proteins can be sterilized by heating for 1 hr at 56oC in a water bath for several successive days. 27 TEMPERATURE AT O 100 C Boiling: Kills vegetative forms of bacterial pathogens. Hepatitis virus: Can survive up to 30 minutes of boiling. Endospores: Can survive up to 20 hours or more of boiling 28 STEAM UNDER PRESSURE - AUTOCLAVE Works on the principle of Steam under pressure Charles Chamberland Invented by Charles Charles Chamberland 1879 Chamberland in 1879. 29 Dr. Ayham Abulaila 30 Autoclave Autoclave consists of a vertical or a horizontal cylinder. One end has an opening which is meant for keeping materials to be sterilized. The lid is provided with a Pressure gauge, to measure the pressure A safety valve is present to permit the escape of steam from the chamber. Sterilization is carried out under pressure at 121º for 15 mints or 132 º for 3 min (flash sterilization) Quality control… 31 CHEMICAL AGENTS Protein coagulation Disruption of the cell membrane Chemical agents act by Removal of Sulphydryl groups Substrate competition 35 Principles of effective disinfection Concentration of disinfectant Organic matter pH Time 36  ALCOHOLS Ethanol /Isopropyl alcohol are frequently used No action on spores Concentration recommended 60-90% in water Uses Disinfection of clinical thermometer. Disinfection of the skin – Venupuncture 37  Formaldehyde & Glutaraldehyde are frequently used Formaldehyde is bactericidal, sporicidal ALDEHYDES & has a lethal effect on viruses. Glutaraldehyde is effective against Tubercle bacilli, fungi and viruses 38 USES FORMALDEHYDE To preserve anatomical specimens Destroying Anthrax spores in hair and wool 10% Formalin+0.5% Sodium tetra borate is used to sterilize metal instruments GLUTARALDEHYDE Used to treat corrugated rubber anesthetic tubes, Face masks, Plastic endotracheal tubes, Metal instruments and polythene tubing 39 HALOGENS Iodine in aqueous and alcoholic solution has been used widely as a skin disinfectant Actively bactericidal with moderate against spores Chlorine and its compounds have been used as disinfectants in water supplies & swimming pools 40 PHENOLS Obtained by distillation of coal tar Phenols are powerful microbicidal substances Phenolic derivatives have been widely used as disinfectants for various purposes in hospitals E.g: Lysol, cresol 41 Hydrogen Hydrogen peroxide is used as an antiseptic to clean wounds and to Peroxide disinfect contact lenses. Its effectiveness is limited by the organism's ability to produce catalase, an enzyme that degrades H2O2. Hydrogen peroxide is an oxidizing agent that attacks sulfhydryl groups, thereby inhibiting enzymatic activity. 42  Ethylene Oxide Colorless ,Highly penetrating gas with a sweet ethereal smell. GASES Effective against all types of microorganisms including viruses and spores Specially used for sterilizing heart-lung machines, respirators, sutures, dental equipment, books and clothing. Also used to sterilize Glass, metal and paper surfaces ,plastics, oil, some foods and tobacco. 43 METALLIC SALTS The salts of silver, copper and mercury are used as disinfectants. Act by coagulating proteins Marked bacteriostatic, weak bactericidal and limited fungicidal activity 44 Sterilisation by filtration Filtration helps to remove bacteria from heat labile liquids such as sera and solutions of sugar, Antibiotics. The following filters are used Candle filters Asbestos filters Sintered glass filter Membrane filters 45 46 RADIATION NON –IONISING, IONISING 48  Electromagnetic rays with longer Absorbed as heat wavelength Used in rapid mass Non- Ionizing Can be considered sterilization of as hot air radiation: sterilization prepacked Syringes and catheters E.g: UV rays 49  X- rays, gamma rays & cosmic rays. High penetrative power IONISING RADIATIONS No appreciable increase in the temperature – COLD STERILISATION Sterilize plastics Syringes, catheters, grease fabrics metal foils 50  Bactericidal ULTRASONIC Microorganisms vary in their sensitivity, AND SONIC hence no practical value in sterilization and disinfection VIBRATION 51  Refernces Murray, Patrick R., MEDICAL MICROBIOLOGY, EIGHTH EDITION ISBN: 978-0-323-29956-5 Lippincotts Illustrated Reviews Microbiology 3rd Edition by Richard A. Harvey Cynthia Nau Cornelissen_Ph.D Jawetz Melnick & Adelbergs Medical Microbiology Review of Medical Microbiology and Immunology, Fourteenth Edition by Warren Levinson, MD, PhD. www.cdc.com  For any question [email protected] 55