Music Disinfection and Sterilization Objectives Understand the terms Disinfection and Sterilization Methods used Choice of a good disinfectant Sterilization controls Disinfection and sterilization are basic components of any infection control program. Disinfection is a process that eliminates many or all microorganisms on inanimate objects except bacterial spores. Chemical and thermal disinfection are such methods. Sterilization describes a process that destroys or eliminates all forms of microbial life and is carried out in healthcare facilities by physical or chemical methods. Steam under pressure, dry heat, ethylene oxide gas, hydrogen peroxide gas plasma, and liquid chemicals are the principal sterilizing agents used in healthcare facilities.
Disinfection and sterilization are essential for ensuring that medical and surgical instruments or other material do not transmit infectious pathogens to the patients. Failure to properly disinfect or sterilize equipment carries not only risk associated with breach of host barriers, but also risk for person-to-person transmission, for example, hepatitis B virus, and transmission of environmental pathogens, for example, pseudomonas. One of the most common methods of disinfection is by using chemicals. They are classified as high-level disinfectants.
Characterized by being sporicidal and if the contact is for long, it can be used as a sterilant, for example, glutaraldehyde. Intermediate level disinfectants. These do not have the capability to inactivate large number of bacterial spores but are effective against M.
tuberculosis, fungi, lipid and non-lipid viruses and hepatitis B virus. for example, chlorine compounds, phenolics, isopropyl alcohol. Low-level disinfectants. These are unreliable against bacterial spores, mycobacterium, and small or non-lipid viruses. These can rapidly kill vegetative bacteria, most fungi, and medium-sized or lipid-containing viruses.
Non-critical items which do not come in contact with sterile areas, body tissues, are acceptable after low-level disinfection, for example, patient's trolley, furniture, etc. The patient care items are classified into three categories according to the risk of infection presented. It is also called the Spalding classification.
The non-critical items come in contact with intact skin, not with mucous membrane, for example, bedpans, chairs, linen, BP apparatus, walls and floors. Low to intermediate level disinfectants is recommended, for example, ethyl alcohol. Semicritical items come in contact with mucous membrane and non-intact skin, for example, respiration tubings, bronchoscopes, endoscopes.
High level disinfectant necessary, for example, glutaraldehyde. Critical items enter tissues or vascular system, for example, surgical instruments, and vascular catheters. Sterilization is necessary.
For example, autoclaving or ETO sterilization. Choice of the right disinfectant is very crucial. The parameters that are important are concentration, physical and chemical factors and exposure time.
Concentration. An optimum concentration of disinfectant ensures greater efficacy and it takes a short time. time to achieve microbial kill.
All areas where this work is done. The instructions must state the concentration that is to be made up and must give a detailed description of the way in which the concentration is to be made up. Do not mix disinfectant with detergents.
They may be incompatible with each other. Several physical and chemical factors also influence disinfectant procedures. such as temperature, pH, relative humidity, water hardness and containers. A great increase in temperature causes the disinfectant to degrade and weakens its germicidal activity and thus might produce a potential health hazard.
An increase in pH improves the antimicrobial activity of some disinfectants but decreases the antimicrobial activity of others. Relative humidity is the single most important factor Influencing the activity of gaseous infectants or sterilants such as ethylene oxide, chlorine dioxide, water hardness, that is high concentration of divalent cations, reduces the rate of kill of certain disinfectants because divalent cations, for example magnesium and calcium, in the hot water interact with the disinfectant to form insoluble precipitates. Containers must be cleaned regularly and must not be topped with fresh disinfectant as the level drops.
The container must be covered with a tightly fitting lid in order to minimize the spread of toxic vapor. Exposure or contact time. Items must be exposed to the germicide for the appropriate minimum contact time.
The efficacy of disinfectants decreases if the contact time with disinfectant is less than desired. Ease of contact with microorganisms. Microorganisms may be protected from disinfectants by production of thick masses of cells and extracellular materials or biofilms. Biofilms are microbial communities that are tightly attached to surfaces and cannot be easily removed.
Once these masses form, microbes within them can be resistant to disinfectants. Bacteria within biofilms are up to 1000 times more resistant to antimicrobials than are the same bacteria in suspension. Biofilms have been found in whirlpools, dental unit water lines and numerous medical devices for example contact lenses, pacemakers, hemodialysis systems, urinary catheters, central venous catheters, endoscopes. Their presence can have serious implications.
for immunocompromised patients and patients who have indwelling medical devices. Organic matter in the form of serum, blood, pus or fecal or lubricant material can interfere with the antimicrobial activity of disinfectants and also act as a physical barrier. Chlorine and iodine disinfectants, in particular, are prone to such interaction. Chemical properties should not be harmful to the item being disinfected. Corrosion of metals or hardening of plastics as seen in case of chlorine compounds.
Remove the corrosive disinfectant soon after application with a neutral compound for example alcohol or soap and water. Disinfectant in use should be easy and safe to handle. Let us look at steps to increase the effectiveness of disinfectants. Cleaning is the most important step in the disinfection process. Organic matter, if present, will dilute the effect of active ingredient in the disinfectant.
If you can't clean, you can't sterilize or disinfect. Cleaning may be done manually or by mechanical cleaning equipment, for example, ultrasonic cleaners or washer disinfectors. The cleaning agent used should be compatible with the device and cleaning method.
It is found that normal cleaning leaves behind residual proteins or biomaterials sticking to surfaces, especially in lumens and hinges. Pathogens trapped under these layers do not get exposure to disinfectant and can lead to infection. Manual cleaning All surfaces of the instrument or equipment must be cleaned taking care to reach all channels and bores of the instrument.
Dry the instrument in either a drying cabinet, or hand dry with clean lint-free cloth. Inspect to ensure the instrument is clean. Place the instruments in a high-level disinfectant, for example, SIDEX.
Multi-enzymatic cleaning. They are better than single enzyme cleaners as they contain multiple enzymes which digest proteins, polysaturates, mucopolysaturates, and lipids. It is thus effective in removing traces of biomaterial sticking to the instruments and may be even used in ultrasonic buds. Ultrasonic cleaners and automated washers are recommended for cleaning basic instruments that can withstand this process.
Using a machine to wash the instruments will cut down on the handling of the instruments. These cleaners must be compliant with national guidelines and standards and must be used according to the manufacturer's instructions. These cleaners are not appropriate for use on cannulated instruments.
They cannot clean inside the instrument. plastic materials, two or more different metals, or some glass instruments, syringes, and lenses. In general, after cleaning, it is important to remove excessive moisture from items because it may dilute the disinfectant solution.
Terms with the suffix side or sidle for killing action are also commonly used. For example, a germicide is an agent that can kill microorganisms, particularly pathogenic organisms or germs. The term germicide includes both antiseptic and disinfectants.
Antiseptics are germicides applied to living tissue and skin. Disinfectants are antimicrobials applied only to inanimate objects. Many disinfectants are used alone or in combinations, for example, hydrogen peroxide and parasitic acid, in the healthcare setting.
Users should read labels carefully to ensure the correct product is selected for the intended use and applied efficiently. Disinfectants are not interchangeable and incorrect concentrations and inappropriate disinfectants can result in excessive costs. Because occupational diseases among cleaning personnel have been associated with use of several disinfectants, for example, formaldehyde, glutaraldehyde and chlorine, precautions, for example, gloves and proper ventilation should be used to minimize exposure. There are various chemical disinfectants used in healthcare setting.
Alcohol, 70%, isopropyl, ethyl alcohol. These alcohols are rapidly bactericidal rather than bacteriostatic against vegetative forms of bacteria. They also are tuberculocidal, fungicidal, and virus idle, but do not destroy bacterial spores. The sidal activity drops sharply when diluted below 50% concentration and the optimum bactericidal concentration is 60% to 90% solutions in water. Recommended use Smooth metal surface and tabletops Alcohols have been used effectively to disinfect oral and rectal thermometer and stethoscopes.
Precautions Flammable, toxic, use in well-ventilated area, avoid inhalation. Keep away from heat sources, electrical equipment, flames, hot surfaces. Allow to dry completely.
They also evaporate rapidly, making extended exposure time difficult to achieve unless the items are immersed. Chlorine and chlorine compounds. Hypochlorites, the most widely used of the chlorine disinfectants.
are available as liquid for example sodium hypochlorite or solid for example calcium hypochlorite sodium hypochlorite 1 percent in use dilution 4 percent solution to be diluted 400 ml of 1 percent sodium hypochlorite take 250 ml of 4 percent sodium hypochlorite and 750 ml of distilled water recommended use disinfection of material Contaminated with blood and body fluids. Spillage. To be changed every 8 hours.
Contact time 15 to 30 minutes. Precautions. Use in well-ventilated areas.
Use protective clothing. Corrosive to metals. Bleaching powder is any of various mixtures of calcium hypochlorite, calcium hydroxide and calcium chloride.
Also known as chlorinated lime. It is used in many of the same applications as sodium hypochlorite, but is more stable and contains more available chlorine. It is usually a white powder.
It is prepared by mixing 14 grams of powder in 1 liter of water to ensure availability of 1% free chlorine. Contact time for disinfection is 30 minutes. Prepare the bleach solution freshly in every shift, that is 8 hours. Bleaching tablets contain calcium hypochlorite and other ingredients to prevent the tablets from crumbling.
Other disadvantages of hypochlorite Include corrosiveness to metals in high concentrations, i.e. more than 500 ppm, inactivation by organic matter, discolouring or bleaching of fabrics, release of toxic chlorine gas when mixed with ammonia or acid, e.g. household cleaning agents. A potential hazard is production of the carcinogen bis-fluoromethyl ether when hypochlorite solutions Contact formaldehyde and the production of the animal carcinogen trihalomethane when hot water is hypochlorinated. Recommended use of bleaching powder.
Cleaning of toilets, bathrooms, precautions. Use in well-ventilated areas. Use protective clothing. Corrosive to metals. Same as sodium hypochlorite.
Alternative compounds that release chlorine. and are used in the healthcare setting include demand-release chlorine dioxide, sodium dichloroisocianurate, and chloramine T. The advantage of these compounds over the hypochlorites is that they retain chlorine longer and so exert a more prolonged bactericidal effect. But with sodium dichloroisocianurate, only 50% of the total available chlorine is free. Glutaraldehyde It is the most widely used for high-level disinfection of reusable, semi-critical items.
Recommended use Use as 2% Sodex for disinfection of endoscopes, surgical instruments, respiratory therapy equipment, and for materials that are destroyed by heat. Contact time is 6-8 hours. Precautions Eye and nasal irritant Use in well ventilated area. Keep covered with well-fitting lids.
Wear eye protection, plastic apron and gloves while handling. Efficacy decreases in the presence of organic and inorganic material. Do not mix with other chemical agent except the activating agent supplied by the manufacturer. Chemical test strips or liquid chemical monitors are available for determining whether an effect concentration of glutaraldehyde is present despite repeated use and dilution.
The frequency of testing should be based on how frequently the solutions are used. For example, if used daily, test daily. Used weekly, test before use.
Used 30 times per day, test each 10th use. But the strips should not be used to extend the use life beyond the expiration date. The result of test strip monitoring should be documented. If the manufacturer of the chemical test strip recommends a quality control procedure, users should comply with the manufacturer's recommendation.
The concentration should be considered unacceptable or unsafe when the test indicates a dilution below the product's minimum effective concentration or MEC by the indicator not changing color. Chlorhexidine combined with alcohol or detergents. Recommended use 2 to 4 percent concentration.
Antiseptic for skin and mucous membranes. Pre-operative skin preparation. Disinfection of hands.
Precautions. Inactivated by soap. Organic matter. Relatively non-toxic. Quaternary ammonium compounds.
For example, Dettol, Cetavlon, Cetramide. Recommended use. Antiseptic for cleaning dirty wounds.
They are low-level disinfectants. Precautions. Use incorrect dilution. Surface disinfection.
Is surface disinfection necessary? Surfaces are considered non-critical items because they contact intact skin. However, regular and scheduled surface disinfection is important because hospital floors become contaminated with microorganisms from settling airborne bacteria by contact with shoes, wheels and other objects, and occasionally by spills.
Detergents become contaminated and result in seeding the patient's environment with bacteria. Mop water becomes increasingly dirty during cleaning and becomes contaminated if soap and water is used rather than a disinfectant. Regularly wash the mop in use. Regularly clean and disinfect the bedside equipment and environmental surfaces, for example, bed rails, bedside tables, carts, commodes, doorknobs and faucet handles because certain pathogens, for example, enterococci, can survive in the inanimate environment for prolonged periods.
Used patient care equipment, for example, needles, syringes, surgical instruments, and other equipment. Equipment Needles and syringes Use disposable only. Standard procedure Discard in puncture-proof container with international biohazard symbol. Commence When puncture-proof container is two-thirds full, seal it and send it for disposal. Needle destroyer Are not recommended.
Contaminated aerosols may arise while destroying the needles. Syringe cutters are not recommended as they can cause splashes. Soiled patient care equipment.
For example, stethoscope, blood pressure apparatus. Standard procedure, clean with detergent and water and dry. May be wiped with sodium hypochlorite 1-2% or 70% alcohol and dried after cleaning.
Always clean between patient use. Cuffs of blood pressure apparatus. Standard procedure. Clean with soap and water followed by appropriate disinfectant.
For example, wash in hot water with detergent. If material is not washable, wipe with sodium hypochlorite 1-2% or 70% alcohol and dry after cleaning. Instruments. Remove all protein, organic, inorganic matter at point of generation. For example, blood and body fluids, secretion and water.
Return to the sterilizing service department for appropriate reprocessing. AMBU bag and mask. Standard procedure. Clean with detergent, dry and send to the sterilizing service department.
Change the mask after each patient. Equipment in the isolation unit. Equipment. Furniture.
Bed. Bedstand. Couch.
Frames. Table. ivy stand, wheelchair, etc. Standard procedure, clean with detergent and water and dry. Wipe with disinfectant such as 70% alcohol or 1% sodium hypochlorite and dry after cleaning.
Keep environment clean. Mattress or pillows, always cover with plastic covers. Standard procedure, clean with detergent and water between patients and as required.
Wipe over with disinfectant such as 70% alcohol or 1% sodium hypochlorite. Discard pillow if cover of pillow is damaged. Change the cover of the mattress if torn or discard mattress depending on the institutional guidelines.
Telephones, dressing trolleys. Standard procedure, clean with detergent and water and dry. Disinfect with 70% alcohol daily. Ventilator suction equipment and mask.
Standard procedure. Clean machine with detergent and water. Dry and disinfect with 70% alcohol. Filters should be single use and discarded. Mask is single patient use and should be cleaned at least daily and also as it becomes soiled.
Discard mask after each patient. Change tubing or filters. every 48 hours.
Ensure tubing is single patient use. Keep used dirty items separate from clean and sterile ones to prevent cross-contamination. Linen.
If reusable, launder as per the institutional guidelines for soil linen. For example, launder in hot water between 70 to 80 degrees Celsius if possible or soak in clean water with 1% sodium hypochlorite for 30 minutes. Wash again with detergent and water to remove the bleach. Mops. Wash mops separately from other cloth or linen.
If reusable, launder as per the institutional guidelines for soiled linen. For example, launder in hot water between 70 to 80 degrees Celsius if possible. Or soak in clean water with 1% sodium hypochlorite for 30 minutes. Wash with detergent and water to remove the bleach.
Dealing with spillage. Liquid spill management. Promptly clean and decontaminate spills of blood and other potentially infectious materials.
Wear protective gloves. Using a pair of forceps and gloves, carefully retrieve broken glass and sharps if any and use a large amount of folded absorbent paper to collect small glass splinters. Place the broken items into the puncture-proof sharps container.
Cover spills of infected or potentially infected material on the floor with papal tal or blotting paper or newspaper. Pour freshly prepared concentrated solution of sodium hypochlorite. Leave for 30 minutes for contact.
Place all Soiled absorbent material and contaminated swabs into a designated waste container. Then clean the area with gauze or mop, with water and detergent with gloved hands. Any material treated with hypochlorite solution should never be sent for incineration. Mercury spill management If accidental spill of mercury occurs, it is to be collected in a special manner as follows.
Spills mercury should be collected with a mercury spill kit containing nitrile gloves, N95 face mask, two pieces of cardboard, two plastic containers, sellotape and flashlight. Do not touch mercury. Remove all jewellery, wear gloves and masks.
Use flashlight to locate and cardboard to bring mercury beads together. Collect with an eyedropper of a syringe and carefully place it or contain in a bottle containing water. Any remaining beads of mercury should be picked up with a sticky tape and placed in a plastic bag properly labelled. The bottle should be sealed with a tape labelled as hazardous waste and securely stored inside another plastic container awaiting final disposal to government-nominated or or authorized mercury dealers.
After mercury has been recovered, the spill area should be covered with calcium sulfide or sodium theosulfate to neutralize it. The reporting formats will be used to report and register any mercury spills or leakages. Microbial contamination of disinfectants.
Contaminated disinfectants and antiseptics have been occasional vehicles of healthcare infections. and epidemics for more than 50 years. Members of the genus Pseudomonas are the most frequent isolates from contaminated disinfectants, recovered from 80% of contaminated products.
The following control measures should be instituted. Some disinfectants should not be diluted. Those that are diluted must be prepared correctly to achieve the manufacturer's recommended use dilution.
Common sources of extrinsic contamination of germicides are the water to make working dilutions, contaminated containers and general contamination of the hospital areas where the germicides are prepared and or used. Stock solutions of germicides must be stored as indicated on the product label. Supervision.
A disinfectant record book should be kept to show the number of containers. the names of disinfectants and the concentration in use. A senior member of the staff must be responsible for the disinfectant record book and for monitoring the use of solution once a week.
Monitoring In-use test is not recommended routinely to monitor the appropriate use of the disinfectant. It should only be carried out during an outbreak or investigation. For in-use testing, collect aseptically about 1 ml of disinfectant, from discard jars or container into sterile bottles, label them and send them promptly to the microbiology laboratory.
Sterilization. Sterilization is the destruction of all microorganisms and can be achieved by either physical or chemical methods. Sterilization is necessary for medical devices penetrating sterile body sites. Cleaning to remove visible soiling and reusable equipment should always precede sterilization. All materials must be wrapped before sterilization.
Only wrapped or packed sterilized materials should be described as sterile. Before any instrument or equipment goes under the process of steam sterilization, the following should be checked. Ensure that the instrument can withstand the process.
For example, steam under pressure. Ensure that the instrument has been adequately cleaned. Ensure that the instrument does not require any special treatment.
Ensure that the records of sterilization process and for the traceability of the instruments are kept. Instruments and equipment will only be sterile if one of the following sterilizing processes is used. Steam under pressure, that is moist heat, dry heat, ethylene oxide, parasitic acid, hydrogen peroxide plasma, and other chemical sterilant systems or sterilants, or irradiation. The above sterilizing methods are designed to give a sterility assurance level of at least 1 in a million as long as the process is validated and is according to the manufacturer's guidelines.
Steam under pressure, moist heat sterilization. This is the most efficient and reliable method to achieve sterility of instruments and equipment. It is inexpensive, non-toxic and very reliable.
There are several types of steam under pressure sterilizers. also called as autoclaves. Downward gravity, displacement sterilizers, jacketed and non-jacketed, these are designed for sterilization of waste, solutions and instruments. Self-contained or benchtop sterilizers, these are recommended for office-based practice as they are able to do small quantities of fairly simple items.
Pre-vacuum or porous load sterilizers, These are not suited for liquid sterilization but are optimized for sterilization of clean instruments, gowns, drapes, tarling and other dry materials required for surgery. All autoclaves are pressure vessels. They must conform with the relevant regulations and are therefore subject to regular inspection for safety purposes.
A clean, separate room is required for autoclave. Appropriate standard procedure should be followed for removing the sterilized items without contaminating while removing. All sterilized items must be placed on a clean trolley wearing PPE. Sterilization controls. There are various methods which are used to check the completeness and efficacy of sterilization process and penetration of steam inside the test load.
Biological testing for sterilization. It is done by using biological indicator. Bacillus, Sterothermophilus, Material required, Commercially available plastic vial containing strip coated with 10 to the power 6 spores of Bacillus Sterothermophilus and inner glass vial containing culture media and water bath. Procedure, the vial is kept inside the autoclave along with the load. After completion of sterilization cycle, that is, At 121°C for 15 minutes, the vial is brought to microbiology laboratory along with filled form which include information about the place, time, holding period, type of load.
The inner vial is crushed with the help of a hard object and it is incubated at 56°C for 2 days in water bath. A control vial is also crushed and incubated. Along with the test vial, spores are destroyed if sterilizing conditions are made. The growth can be read manually or with the help of an auto-reader.
With the use of an auto-reader, results can be obtained within 1 to 3 hours. Interpretation Growth is indicated by change of color in the vial. For example, violet to yellow after incubation period. No color change indicates Sterilization process by autoclave is complete and the report is sent as satisfactory while change in color indicates improper sterilization cycle and report is sent as unsatisfactory. Test is valid only when controls show color change.
Turnaround time is 3 days. Bowie-Dick test. It demonstrates even and rapid penetration of steam in a steam sterilizer or autoclave. If air and non-condensable gases are not removed from the chamber and the load or from the steam supply, they may become trapped within the load.
This would prevent penetration of that part of the load by steam and consequently sterilizing conditions may not be obtained. Materials used Towels Ideally, huckaback towels are used. They are thoroughly washed after purchase and before use. The towels should not be starched or ironed and should be washed once a week.
The tape recommended is autoclave tape which is normally used as a process indicator. The paper should be an A4 sheet of white wood free copier paper. Procedure.
Making the test pack. Each towel should be folded in half three times to provide eight thicknesses and placed one on top of the other to form a stack of 30 cm x 22 cm x 27 cm. About 25-30 towels may be needed. The stack may be placed in a dressing casket or a box made of cardboard or metal which is not airtight. The stack can be wrapped in linen, paper or secured with tape.
An adhesive tape which is printed with a chemical substance is fixed in the shape of a cross. This test sheet is placed in the center of a stack of towels. The test pack should be placed on the longitudinal center line of the chamber 10 cm away from any door and 10 cm above the chamber base of an otherwise empty sterilizer.
The tiles should be lying horizontally. It must be subjected to standard sterilizing cycle. The holding or sterilizing time should not be more than 3.5 minutes at a temperature of 134°C.
to 138 degrees Celsius. Reading the test. The tape will show a uniform color change if all the air is removed and steam penetrates rapidly and completely. If all the air is not removed then air will collect in the form of a bubble.
The color of the tape in the region of the bubble will be paler than elsewhere because of the low temperature and reduced moisture level. Chemical indicators are also commercially available. Physical indicators to check sterilization process are temperature and pressure monitors.
They can be in the form of graphs formed in each sterilization cycle.