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STERILISATION, DISINFECTION & ASEPTIC TECHNIQUE Presented by Mrs C.B. Bello CHAIN OF INFECTION • An infection is the invasion of a susceptible host by pathogens or microorganism resulting in disease. • The presence of a pathogen does not mean an infection will occur. Infection occur in a cycle that depends on the presence of all of the following elements: An infectious agent or pathogen A reservoir or source for pathogen growth A port of exit from the reservoir CHAIN OF INFECTION CONTD A mode of transmission A portal of entry to a host A susceptible host INFECTIOUS AGENT • Micro-organisms include bacteria, viruses, fungi, and protozoa. • When on the skin, can be resident or transient. Residents micro-org (normal flora) are permanent residence on the skin, they multiply and survive without causing dx. • Factors that affect potential of micro-organism to cause dxes are: the number of micro-organism present, the susceptibility of the host, the virulence of the micro-organism, • Resident micro-organism do not cause dx except INFECTIOUS AGENT CONTD • When invasive procedures allow them to leave normal abode and enter into deep tissues. Or when the host is immuno-compromised (have an impaired immune system). • Transient micro-organisms attach to the skin when a person come in contact with another person or objects during normal activities e.g., contaminated clothing's and dressings. • This micro-organisms can easily be removed through effective hand hygiene. A RESERVOIR • A reservoir is the place where micro-organisms survive, multiply, and await transfer to a susceptible host • Common reservoir are human and animal host, insects, food water and or organic matters or inanimate surfaces (fomites) • Frequent reservoirs for health care associated infections are, health care workers, especially their hands, patients, equipments and the environment. • Human reservoir can be those with acute or symptomatic disease or those who show no symptoms but are carriers of the disease. MODES OF TRANSMISSION • Direct transmission: direct contact , skin to skin, mucosa to mucosa, skin to mucosa droplet infection, from coughing, sneezing, speaking contact with soil inoculation into skin or mucosa • Indirect transmission: vehicle borne; water, food, raw veg, fruits, milk & products Vector borne; cockroaches, flies, mosquito, rodents etc Airborne Fomite-borne; towels, linen, handkerchief, sphyg etc Unclean hands & fingers MODES OF TRANSMISSION CONTD • Each disease has a specific mode of transmission • Major routes of transmission in health care settings are: o unwashed hands of health care workers o equipments, e.g. stethoscope, blood pressure cuff, bedside commode. PORT OF ENTRY • Organisms enter the body through the same routes they use for exiting e,g a needle a patients skin, organism enters the body if proper skin preparation are not performed. SUSCEPTIBLE HOST • This is individuals degree of resistance to pathogens. • Even when an individual is exposed to lots of microorganisms, an infection does not occur until an individual become susceptible to the strength and number of the microorganism • A persons natural defense is important • A persons age, nutritional status, presence of chronic disease, trauma, smoking are factors that affect the susceptibility to infection. CONCLUSION • Your understanding of the chain of infection is to provide knowledge that is vital in understanding that the procedures of sterilization, disinfection and practices of surgical asepsis are measures to break the chain of infection at one point or the other in order to prevent transmission of infection. DEFINITION OF TERMS • Asepsis: it’s the absence of pathogenic (diseaseproducing) microorganisms. • Aseptic technique: Practices/ Procedures that help reduce the risk of infection. There are 2 types of techniques. Surgical & medical asepsis • Medical Asepsis: this is referred to as the clean technique, the aim is to reduce the number of microorganism present in a field and preventing further transfer of organism. Medical asepsis measures include hand hygiene, barrier technique & routine environmental cleaning. DEFINITION OF TERMS CONTD • Medical asepsis is commonly practiced at home, on medical wards etc. • Surgical asepsis: it is also referred to as surgical technique. The aim is to eliminate all microorganism including there spores present in a field, measures include surgical hand scrub, sterilization of equipments & articles, using of sterile drapes etc. this principle is commonly used for surgical procedures such as surgeries, wound dressing, catheterization, parenteral drug administration etc. DEFINITION OF TERMS CONTD • Contamination: this is when an object come in contact with an infectious or potentially infectious material. The object is discarded if disposable but if reusable, it is cleaned, disinfected or sterilized depending on use. • Sterile STERILISATION INTRODUCTION • Sterilisation is the process whereby all microorganisms (pathogenic & non-pathogenic) including their spores are destroyed. An item become sterile following sterilisation. • The term “sterile’’ is an absolute term, an item is either sterile or not sterile, there is nothing like near sterile or almost sterile. • Pathogenic micro-organism are those that are capable of causing infection if they get introduced to the body tissues • It is important that hospital provide specific • principles and practices for sterilization of all items safe for use and reduces the transmission of infection as long as sterility is maintained. • Bacteria spores are the most resistant of all living organisms because of its ability to withstand external destructive agents, therefore, any method that is not capable of destroying spores is not referred to as a sterilization method. • The selection of a sterilization method depend primarily upon the nature of items to be sterilized. METHODS OF STERILIZATION • There are physical and chemical methods. • 1. Physical methods a)Moist heat (steam under pressure or autoclaving) b)Dry heat (hot air oven) c) Radiation 2. Chemical methods a)Ethylene oxide gas b)Vapour phase Hydrogen Peroxide MOIST HEAT • Most efficient method, popular in the hospital & reliable. Moist heat in form of steam under pressure is a reliable physical agent in the destruction of microbes including their spores, at temperature of 1210c for 15mins under great pressure or a flash sterilization at 2700c for 3mins. • Death of micro-organism is by denaturation & coagulation of protein system of the cell. • A special equipment called autoclave is required, an autoclave is like a jacket inside another jacket, steam is formed and introduced into equipments/ • materials in the inner chamber under a very high pressure for the stipulated period of time. • Precautions – Items must be free from grease, oil or stain – Materials must be arranged to allow flow of air – Timing of cycle must be adjusted for different materials • Suitable for stainless steel materials such as bowls, gallipots, receivers, instruments, linens, rubber goods, dressings, glassware • Not suitable for powders and anhydrous oils. • • • • • • • • Advantages: Easiest and safest Very reliable and efficient Fastest method Least expensive and available Has no harmful residue Disadvantages: Special precautions is required in preparing, packaging, loading and operating an autoclave DRY HEAT • Dry heat in form of hot air at 1600c for 2hours using a hot air oven is used for heat stable materials, glass-wares, glass syringes, capillary tubes, slides, needles, oils and powders. • Destroys microorganism by coagulating the protein unit of the cell of the microorganism. Commonly used in medical laboratory to sterilise items such • Advantages -Hot air penetrates certain substances that cannot be autoclaved or may be damaged by moisture -suitable for goods that cannot be disassembled. • Disadvantages -long exposing period is required because hot air penetrates slowly & unevenly. -over exposure to heat may ruin substances or materials -it’s destructive to fabrics and rubber goods. RADIATION • Used mainly in industries, packaged materials such as pre-packed disposable syringes, catheters, Naso-gastric tubes, sterile gloves etc. • Both ionizing (alpha, beta rays & x-ray) and non ionizing (ultraviolet) radiation are used for disinfection & sterilization but ultraviolet rays do not penetrate deeply • Ionizing radiation is used in industry more effectively to sterilize foods, drugs, & above • Advantages: -Good for sterilizing bulky items even in their cartons ready for shipment -Effective for items that are difficult to sterilize e.g. If both sensitive to heat and moisture. • Disadvantages -Equipment for sterilization is expensive ETHYLENE OXIDE GAS • Used to sterilise items that are heat or moisture sensitive effective at low temperature. • It interferes with normal metabolism of protein & reproductive process resulting in the death of cells. • Its used in gaseous state, highly inflammable & explosive hence usedalong with an inert gas (CO2) • Advantages -Provides effective method for goods that can be damaged by moisture. -Has good penetrating power -Compatible with most medical material • Disadvantages -Expensive -Leaves toxic by products -Highly inflammable & explosive -If inhaled, can be irritating to the mucous membrane • • • • • CENTRAL STERILE SUPPLY DEPT (CSSD) Cleaning disinfection & sterilization of client’s supplies should be performed in the CSSD, this unit should be responsible for all the sterile supplies needed in all the wards & units of the hospital The department should be divided into several areas separated by physical barriers. Monitoring sterilization process is important in the CSSD to ensure efficiency. Temperature in the CSSD should be 18oc -22oc while humidity should be between 35% -70% Airflow should be directed from clean to relatively soiled areas DISINFECTION DISINFECTION • This is the process of destroying all micro-organism except spores (Rutala & Weber, 2009). • METHODS OF DISINFECTION • Boiling: most micro-organism are killed by 5mins boiling at 100oc, spore forming organism & thermophillic micro-organism are not, hence not sporicidal • Equipments cannot be guaranteed sterile if processed in this manner, instruments, stainless / enamel/ steel such as bowls, kidney dishes, urinal, bedpans are sterilised using such method. • Lensed and sharp edged instruments should not be boiled. • Pasteurization: this is immersion in water at 75oc – 850c for 10mins, commonly used for lensed instruments (endoscopes). A thermostatically controlled water bath is used, non boilable instruments can withstand this. • Formalin vapour + steam under pressure: dismantled instruments are exposed to formalin vapour with steam under atmospheric pressure e.g. lensed instrument. • Sunning: pillows, mattresses, sandbag • Freezing: food and drinks • Chemicals: are capable of destroying microorganism. CLASSIFICATION OF CHEMICAL DISINFECTANTS • Low level disinfectants: can kill only vegetative bacteria & enveloped viruses but not the tubercle bacilli, spores or small & non-lipid (non-enveloped) viruses, though it may kill fungi after prolonged contact. • Intermediate level disinfectants: kill vegetative bacteria, tubercle bacilli, fungi & enveloped viruses, has no effect on spores &non enveloped (non-lipid) viruses at normal contact times • May exhibit limited virucidal (against non-enveloped) activity on prolonged contact. (chlorine compounds, alcohols). • High level disinfectants: kill all except spores, are capable of actual sterilization at extended contact times. (2% Glutaraldehyde, may be sporicidal when activated (Cidex), Chlorine dioxide, Peracetic acid FACTORS AFFECTING DISINFECTANTS • • • • • • • Chemical component Concentration of solution pH of the medium Temperature of environment (best at room temp) Volume Duration of contact Length of storage FACTORS AFFECTING DISINFECTANTS • • • • Nature & amount of contamination Presence of inactivating substances Surface areas to be disinfected Prior cleaning to remove organic material-blood, pus, saliva, body excretions. • Presence of soap- soap causes certain disinfectants to be ineffective • Always use disinfectants according to manufacturers instruction. • Disinfectants must be supplied by the pharmacy at RATIONALE FOR CHOICE OF PROCEDURE • Based on categorizing medical devices, equipments and surgical materials on basis of risk of causing infection. • The “Spaulding” classification is a traditional approach used to determine the level of disinfection or sterilisation required for reusable medical devices based on the degree of risk for transmitting infections if the device is contaminated at the time of use. • Critical • Semi-critical CRITICAL ITEMS • Instruments or objects that will be introduced directly into the body tissue or blood stream or into other normal sterile areas are critical items. • Examples are: Surgical instruments, implants, blood compartment of haemodialyzer, cardiac, intravascular or urinary catheters etc. • The minimum standard required is sterilization. SEMI-CRITICAL ITEMS • This are items that come in contact with intact mucosal surfaces but do not ordinarily penetrate body surfaces • There is intermediate risk of causing infection, for example, non-invasive flexible and rigid endoscopes, endo-tracheal tubes, cystocopes, diaphragm fitting rings. • Sterilisation is preferred but not absolutely essential, a high level disinfection procedure that can be expected to destroy vegetative microbes, most fungal spores, tubercle bacilli & small nonlipid viruses can be recommended. NON-CRITICAL ITEMS • These are items that come in contact with intact skin but not mucous membranes • They have a low risk of transmitting infection .e.g. crutches, blood pressure cuffs, stethoscopes, tourniquets, bed rails, food utensils, bedside trays, bedpan • Cleaning with water & detergent may be adequate but a low level disinfectant may be preferred in all cases PRECAUTIONS • Rinse all items to be sterilized or disinfected thoroughly in cold water using a brush & soap under running water • Take extra care to remove blood stain, dirt, clots, oil or grease from items. • Dismantle where possible so that heat/steam/chemical can penetrate all parts of the article • Arrange items to allow free flow of chemicals/steam/heat • Dry items properly after washing/ cleaning before commencing on any method of sterilisation/disinfection • During disinfection, ensure that items are properly immersed, allow solution to cover the items • Leave items in solution for a stipulated length of time • Consider that the method of sterilization/ disinfection chosen is appropriate for a particular item • Follow all important details or information about your method. e.g. packaging & loading in autoclaving & strength of chemicals or any special information concerning the machine in use. • Use cold water rather than hot in washing items, use soap if oily. EXAMPLES OF DISINFECTANTS/ ANTISEPTICS • Phenolics: has bactericidal effect in 10mins, usually corrosive, used with bedpans shelves, incubators, floors, walls slashed with exudates, linen. Examples, Carbolic acid, Lysol, Sudol, Izal, Hexachlorophene • Halogens & halogen containing compounds: has bactericidal effect, used in cleaning floors, walls, glassware, to irrigate wounds. Examples, iodine, chlorine compounds such as Eusol. Hypochlorite (Jik)Iodine stains, chlorine bleaches & its corrosive • Aldehydes: capable of disinfection by precipitating protein in the cell of bacteria, widely used for lensed instrument, its expensive. • Diguanides: e.g. Chlorhexidine (hibitane) a wide spectrum antisceptics, e.g. Hibitane 4% in detergent (Hibiscrub) used for surgical hand scrub, used with ethyl alcohol to disinfect lensed instrument, aqueous dilution of 1% used for vaginal douche or for cleaning fresh wounds • Quanternary Ammonium compounds: e.g. Cetrimide– 1% in soap Phisottex) used in skin preparation during surgery • Heavy metals • Mercurial- precipitate protein & inhibit production of useful enzymes in the cell, highly toxic example, Mercurial bichloride used in disinfection of unbroken skin. • Silver nitrate: silver nitrate 1 in 1,000 useful in gonococcal infection of the eye in the newborn, reduces infection in burns wound. • Oxidising agents: this agent exert microbial actions by oxidation – Hydrogen peroxide- to disinfect wound – -Potassium permanganate- used in wiping skin lesions, 1 in 1,000 RULES FOR USE OF DISINFECTANTS • • • • • Follow manufacturer’s instruction Check expiry date of solution Ensure optimum dilution Always wash and clean articles before disinfection Do not refill disinfectant containers between each use, topping up is not allowed • Disinfectant should be supplied ready for use from the pharmacy • Return empties to pharmacy- do not discard or use for other purpose • Where disinfectant are indicated for use on the surface, WIPE, DO NOT BATHE CLEANING • Cleaning is the removal of organic & inorganic substances from objects or surfaces (Rutala & Weber, 2009). • It involves the use of water and detergents with mechanical force. • Reusable objects must be properly cleaned when they come in contact with infectious or potentially infectious materials before they are taken through the process of sterilization and disinfection. CLEANING CONTD • Cleaning is an essential preparation of equipment prior to sterilization or disinfection as the presence of organic matters in items reduces the effectiveness of sterilizing and disinfecting agents. • Cleaning with water & disinfectants removes contamination physically • Staff must wear protective clothing (water proof gloves) while carrying out cleaning • Water must be below 45o to prevent protein coagulation of organism on the instrument being cleaned. • The articles must first be rinsed with cold running water to remove organic materials such as blood, fecal matter, mucus, or pus. • Avoid the use of hot water as this coagulate the protein of the organic materials, this becomes very difficult to remove • Wash the articles after rinsing them in warm water that contains detergent, the combination of warm water and soap facilitate emulsification and removal of dirt, oil, grease, blood, clot and debris. • Use a brush with stiff bristles, friction aids the removal of organisms and debris in difficult to reach areas CLEANING CONTD • Contaminated materials are easily dislodged using friction. • Rinse object in warm water • Dry properly and ensure that objects are not wet • Prepare the object for the best method of disinfection or sterilization. • Discard gloves, wash properly the brush and sink used for the cleaning and keep for next use ASCEPTIC (STERILE) TECHNIQUE STERILE TECHNIQUE • Sterile technique or surgical asepsis refers to practices that make objects & environment free from all micro-organisms, it includes practices that destroy all micro-organisms and spores they help to ensure that contamination with micro-organism & spores are prevented throughout a surgical procedure involving sterile areas of the body. • Sterile technique is practiced in operating rooms & special diagnostic areas; it is also employed for many procedures in the general care areas such as administering injections, ivs, wound dressing etc PRINCIPLES OF STERILE TECHNIQUE • All articles to be used in sterile procedure must be properly sterilized • Sterile objects become unsterile when touched by unsterile objects • If in doubt about sterility of any item, consider as not sterile • Non sterile person must avoid reaching over a sterile field & vice versa. • Tables, trolleys, trays are sterile only at table, trolley & tray level • Never turn your back on a sterile field • The skin cannot be sterilised and is unsterile • Fluid flow in the direction of gravity. Always hold wet forceps with the tip below the handle • The edges of anything that enclosed sterile contents are considered unsterile • A sterile field is continually kept in view • Sterile person keep well within sterile areas and vice-versa • Sterile objects can become unsterile by prolonged exposure to airborne microorganism hence a sterile field is created as close as possible to the time of use • Hold sterile objects at the level of the waist, object above or below are regarded as unsterile. • Sterile persons keep well within sterile area to a minimum • Moisture or wetness causes contamination hence damp or wet packs especially if using an autoclaving method is considered not sterile • No compromise with sterility, conscientiousness, alertness STERILE CONSCIENCE • Keywords in nursing practice is caring, conscience, discipline and technique, optimum client care require an inherent sterile conscience , self discipline & application of the principles of sterile technique’. • Florence Nightingale summarized in her words “the nurse must keep a high sense of duty in her own mind, must aim at perfection in her care & must be consistent always in herself”. • Sterile conscience is one’s inner voice for conscientious practices of sterile technique at all times. This does not permit a person to excuse an error but rather to readily admit & rectify • It becomes so much a part of the person that he/she can see at a glance or instinctively know if a break in technique or violation of principles occurs • Conscience dictates that appropriate action be taken whether the person is with others or alone, a surgical conscience therefore is the foundation for practices of strict sterile technique practice • A very important aspect in assisting the development of a surgical conscience in others is not to castigate a person of an error but praise the person instead, for admitting & to help him/her correct the violation, fear of criticisms is the primary deterrent in admission of fault. No one should question a break in technique. REFERENCES • Potter , P. A., Perry, A. G., Stockert, P. A., Hall, A. M. (8th edition) Fundamentals of Nursing. Elsevier Mosby, Missouri • Berman, A. Synder, S. J., Kozier, B., Erb, G. (8th edition) Kozier & Erb’s Fundamentals of Nursing Concepts, Process, and Practice. Pearson Prentice Hall, New Jersey • Park, K. (18th ediition) Park’s textbook of preventive and social medicine. Banarsidas Bhanot Publishers, India. THANK YOU ALL FOR LISTENING