Disinfection Control: How to Select and Control Disinfectant Solutions?
Sterilization, decontamination and disinfection form the basis of the infection control program. Procedures to prevent cross-infection must be performed on vehicles used repeatedly for diagnostic and therapeutic purposes. It should be kept in mind that the insufficiency of sterilization and disinfection of medical devices may lead to extra treatment expenditures, more importantly morbidity and mortality in the patient, unnecessary procedures for sterilization-disinfection will increase hospital expenses and cause selection of resistant microorganisms.
The most suitable option for cross-contamination prevention is disposable, single-use tools. However, it is not always possible to use disposable instruments because some vehicles are too expensive or the vehicle cannot be disposed of. If the medical and surgical interventions cannot be obtained as a disposable device, the first method of sterilization or disinfection is heat. However, plastics, rubber, silk, electronic devices and so on. materials can not be used in heat, irradiation sterilization can not be provided, disinfectants are used.
Disinfectants are divided into two groups as gas and liquid. The effectiveness of the disinfectants is influenced by the cleaning process before disinfection, the type of microorganism, the level of contamination and the type of disinfectant, the concentration of germicidine used, the duration of application, the physical configuration of the object (whether a narrow canal or slit, etc.), and the temperature and pH during the process. It is of no use to keep a vehicle in the disinfectant longer than recommended. This may cause irreversible damage to the vehicle.
Before using disinfectant, cleaning should be used as much as possible. The device and the surface to be treated should be washed with hot water and detergent if possible. It has been experimentally demonstrated that 99.99% or 4 log of viruses and vegetative bacteria are reduced by this process. In addition, these residues cause the disinfectant not to reach the microorganism or react with organic substances to lose its activity.
Ethylene oxide gas disinfectant is generally used for instruments to be sterilized. It is the most commonly used sterilization method after heat. It can be used safely in sterilization of fine hole and narrow groove instruments due to its higher penetration ability compared to liquids. Sterilization with ethylene oxide is carried out in about four hours, but for about 12 hours or more, it is expected to remove the toxic oxide ethylene. It should be noted that ethylene oxide is an explosive, carcinogenic and toxic gas.
Gas plasma has been developed as an alternative to sterilization with ethylene oxide. Plasma is, as we know it, a liquid medium containing free ions. Germicidal chemical agent is ionized with radio waves under vacuum and mixed with air is called gas plasma. Plasma form is also called the fourth state of matter. Hydrogen peroxide is a strong germicidal agent with sporicidal activity in liquid form. The gas plasma obtained from hydrogen peroxide has germicidal activity to provide sterilization. Hydrogen peroxide in the form of gas plasma has no corrosive effect. Active ions lose energy as they kill microorganisms and become completely non-toxic products by removing ionizing waves and vacuum. The use of gas plasma sterilization techniques using chlorindioxide, ozone, ethyl alcohol, peracetic acid and various mixtures of these substances is under investigation and some of them have begun to be used. Sterilization is achieved in as little as thirty-sixty minutes. However, it can be used for sterilization of small volume devices. The packages should not be made of paper and fabric, but made of polyethylene or propylene.
The practical side of the method is that it does not require a special tool for the use of liquid disinfectants. The degree of activity is different. In addition, the response of microorganisms to disinfectants is different. Very little disinfectant, known as chemical sterilizer, removes all microorganisms including spores in as long as six to eight hours. At the same concentration, it kills all microorganisms except for some bacterial spores in a much shorter period (20-30 minutes). Therefore, these disinfectants are also called high-level disinfectants. Although there is no sporicidal activity, disinfectants with tuberculocidal activity are defined as moderate disinfectants, but disinfectants with no tuberculocidal activity, but with HIV-including virucidal activity are defined as low-level disinfectants ( Figure 1 ).
The tools used in the hospital vary according to the risk of infection. The choice of disinfection method is determined by the level of infection risk of the vehicles. According to this;
1. Critical means: Direct contact with normally sterile tissues, body cavities and body fluids.
2. Semi-critical tools: Those who come into contact with the mucous membranes but do not penetrate the body.
3. Non-critical tools and substances: Those who do not come into direct contact with the person or who only come into contact with intact skin.
The availability of critical devices depends on their sterility. Many such instruments are either disposable or heat-sterile. However, as described above, heat cannot always be applied for some reason.
The next method to be proposed is sterilization with gas disinfectants (eg ethylene oxide, gas plasma method). Besides being an effective method, it is important for sterilizing large instruments that cannot be immersed in disinfectants. It is conceivable to wipe such instruments with disinfectant, but this applies to semi-critical and non-critical vehicles. In addition, some vehicles may be damaged if left in disinfectants for a long time. Liquid disinfectants are most commonly used in gluteraldehyde, formaldehyde, chlorindioxide, hydrogen peroxide or formulas. The most commonly used formulations are 7.5% hydrogen peroxide in addition to 2% gluteraldehyde, peracetic acid in less than 1% concentration, or combinations of 0.08% peracetic acid and 1% hydrogen peroxide. Sporocidal activity can only be achieved by prolonged application of an effective disinfectant to bacterial spores (6-20 hours depending on the type of disinfectant). Orthophitalaldehyde, which has been approved by the Food and Drug Administration (FDA) in recent years, is a high level disinfectant used in American and European countries. It does not need to be activated for use, is less irritant to the eye and respiratory tract, and has no advantage over gluteraldehyde in terms of sporicidal activity, but the effect on mycobacteria is much earlier.
The instrument is washed three times with sterile distilled water after treatment with disinfectants. It is then dried with a sterile towel using sterile gloves and made ready for use.
At the end of these procedures, the bacterial spore may remain. However, their number has decreased considerably and they are particularly spores of saprophyte microorganisms. These microorganisms are destroyed by body resistance. However, this idea is not always valid. Even the Bacillus subtilis , known as nonpathogenic, can cause serious lethal infections where the resistance of the host is low, such as immunodeficient or immunosuppressed patients.
Sterilization of vehicles contaminated with Creutzfeldt-Jakob prion cannot be achieved by normal procedures. Vehicles with high risk for prion, such as the brain, dura material or cornea, should be treated with 1 N NaOH at room temperature after sterilization for 30 minutes at 132 ° C or alternatively for 30 minutes at 121 ° C. “Centers for Disease Control and Prevention (CDC) alternatif has introduced a practical approach as an alternative and reported that after cleaning the vehicle, a pre-vacuum sterilizer is sufficient for 18 minutes at 132-134 ° C and one hour at 121 ° C. Normal sterilization programs have been recommended by CDC for contamination with organs such as cerebrospinal fluid, spleen, kidney, lymph node. For non-critical vehicles, 15 minutes of treatment with 1 N NaOH at room temperature is sufficient.
In disinfection of semi-critical devices, it is aimed to kill all microorganisms except bacterial spores. Some of the spores are devastated when these operations are performed.
Here, if the structure of the substance is appropriate; heat sterilization or disinfection at 75 ° C for 30 minutes at humid temperature is preferred. High-level disinfectants are generally used in the disinfection of semi-critical vehicles, with phenol compounds, iodophores, chlorine compounds being preferred from intermediate disinfectants. Flexible fiber-optic endoscope, laryngoscope, vaginal speculae, anesthesia respiratory circulation devices, ophthalmic instruments and some dental instruments (amalgam condenser) are in this group.
Cross-contamination is frequently observed with medical devices such as flexible endoscope, bronchoscope, arthroscope. In the clinical course ranging from asymptomatic colonization to death, as a result of gastrointestinal endoscopy, Salmonella and Pseudomonas aeruginosa ; Mycobacterium tuberculosis , atypical Mycobacteria , P. aeruginosa are the most common infections after bronchoscopy. The biggest problem is hepatitis C and multidrug resistant M. tuberculosis after bronchoscopy. Transcontamination with endoscopes is most commonly observed after retrograde cholangiopancreatography. The most common causes are inadequate pre-cleaning, poor selection of disinfectants, deficiencies and inaccuracies in disinfection procedures. Hypochlorite, iodophore and phenol derivatives should not be used against the risk of damage to such valuable instruments and gluteraldehyde, hydrogen peroxide, peracetic acid, orthophitalaldehyde or derivatives should be used. Although it is theoretically known to leave in 2.4% gluteraldehyde solution for 45 minutes at 25 ° C for high-level disinfection, after 20 minutes of use of an FDA-approved sterilized effective disinfectant with a temperature of 20 ° C for bronchoscopes after the FDA standard cleaning protocol, to achieve high level disinfection It was sufficient for. In recent years, the use of orthophitalaldehyde for high-level disinfection has become widespread, with the use of orthophitalaldehyde at a concentration of 0.55% at 20 ° C for 12 minutes in the United States, 10 in Canada, and five minutes in Europe, Asia and Latin America. it is indicated.
In recent years, the use of both washing and disinfection tools has become widespread. Peracetic acid (Steris System I) is used as the high level disinfectant in these devices which have been FDA approved and these devices are used for disinfection of endoscopes.
After disinfection, it is preferred to wash the semi-critical means with sterile distilled water. Non-tuberculous mycobacteria and Legionella contamination from tap water may occur. In case tap water is used, the device is re-disinfected with alcohol, allowed to dry and ready for use.
Hepatitis viruses and HIV do not resist medium disinfection. However, in the case of contamination with these viruses, a high level of disinfection is recommended for semi-critical means.
The low-level disinfection application for non-critical devices aims to kill vegetative forms of bacteria and lipid-containing viruses. The instruments in this group can be divided into two groups as low risk and minimal risk. Materials such as beds, bed sheets, which come into contact with intact skin, fall into the low risk group and if it is not contamination, it is sufficient to disinfect them by means of heat and water (wash with hot water, etc.) and moderate disinfection is required.
For minimal risk vehicles and floors that do not come into contact with intact skin, cleaning with detergent water is sufficient and low level disinfection is applied. Disinfectants can be used in case of contamination by the patient's body interests. Lower concentrations of hypochlorite, iodophores and phenol compounds can be used from quaternary ammonium compounds from low-level disinfectants or from mid-level disinfectants. In this type of disinfection, 10 minutes of application is sufficient. In addition, 70-80% alcohol is useful for rapid disinfection of aerosol-contaminated surfaces, such as in dentistry.
The number of disinfectants used in the hospital should be minimized as much as possible. Those who have been approved by serious institutions (FDA approval, CE marking), whose efficacy has been determined both in the country of manufacture and in the microbiology laboratories of the marketed country should be preferred. In addition, the disinfectant planned to be taken should be evaluated in terms of its practicality, degree of irritation and its corrosive effect, and the most appropriate choice should be made in consultation with the centers that use the disinfectant before intake ( Table 1 ). The use of unnecessary disinfectant causes economic losses as well as the selection and colonization of resistant pathogenic strains due to disinfectants used.
The efficiency of heat and gas sterilization can be routinely investigated. However, there is no routine method for determining the effectiveness of liquid disinfectants. Therefore, full compliance with the literature-supported package insert of the chemical disinfectant to be used will provide an effective disinfection.
Disinfectant solutions should be freshly prepared. The toxicity, odor and activity of the disinfectant are important and disinfectants that change odor and color should not be used. Some disinfectants are known to react with detergents. If the environment is wet after this process should be dried. Any material left wet forms a favorable environment for the growth of microorganisms.
DISINFECTION OF HOSPITAL ENVIRONMENT
Washing with water and detergent is considered to remove 80% of the microorganisms. If disinfectant is used, this ratio reaches 90-95%. Whether or not disinfectant is used in a circulating intensive hospital, the number of microorganisms in the ground will return to the previous level within one to two hours. Therefore, if there is any contamination; In hospital disinfection, it is sufficient to clean the environment with plenty of detergent water (which is preferred to be hot) which is changed frequently. The situation in ICU and operating room is not much different. It is not important to place disinfectant-wetted mats and shoe covers on the entrance doors of such units. Transmission of manual infection is a priority. Drying the environment after cleaning is more effective than disinfectants in preventing the growth of microorganisms.
The floor contaminated with blood and other materials of the patient should be disinfected after wiping with detergent water. Hepatitis B virus (HBV) can survive for one week in dry conditions under appropriate conditions. However, it is very sensitive to disinfectants. In practice it is recommended to use hypochlorite solutions as surface disinfectants and liquid soap as detergents. CDC recommends pouring 1/100 dilution hypochlorite (5000 ppm) onto the decontaminated area with blood and allowing it to stand for 10 minutes.
Disinfectant can be used after cleaning the surfaces which are in constant contact such as benches and tables in the hospital. Hypochlorite can be used in room disinfection after discharge from patients infected with methicillin-resistant S. aureus (MRSA) and similar pathogen agents in addition to viruses. Alcohol solutions containing 70% alcohol are used for disinfection of these surfaces. Although microorganisms cannot enter the body through intact skin, contamination from wounds and fractures can occur. This is one of the reasons why staff working in hemodialysis and serology units have more frequent HBV infections than the normal population.
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