STERILIZATION AND DISINFECTION

STERILIZATION AND DISINFECTION
Meral Sonmezoglu, MD. Professor of Infectious Diseases 2007

DEFINITIONS Decontamination: Removal of disease-producing m.o. to leave an item Disinfection: Inactivation of disease-producing m.o. (not destroy) Sterilization: Destruction of all forms of microbial life (bacteria, viruses, spores, fungi) Sanitation: A process that reduces mo on an inanimate object to a level of below infectious hazard 2007

Disinfection—The process of microbial inactivation that eliminates virtually all recognized pathogenic microorganisms, but not necessarily all microbial forms (e.g., spores) Sterilization—The use of physical or chemical procedures to destroy all microbial life, including large numbers of highly resistant bacterial endospores. Procedures include— Steam sterilization Heat sterilization Chemical sterilization 2007

Efficacy of Disinfection/Sterilization
Cleaning of the object Organic and inorganic load present Type and level of microbial contamination Concentration of and exposure time to disinfectant/sterilant Nature of the object Temperature and relative humidity 2007

Non-Enveloped Viruses
Decreasing Order of Resistance of Microorganisms to Disinfectants/Sterilants Prions Spores Mycobacteria Non-Enveloped Viruses Fungi Bacteria Enveloped Viruses 2007

Disinfection and Sterilization
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. 2007

Processing “Critical” Patient Care Objects
Classification: Critical objects enter normally sterile tissue or vascular system, or through which blood flows. Object: Sterility. Level germicidal action:Kill all microorganisms, including bacterial spores. Examples: Surgical instruments and devices; cardiac catheters; implants; etc. Method: Steam, gas, hydrogen peroxide plasma or chemical sterilization. 2007

Critical Objects Surgical instruments Cardiac catheters Implants 2007

Chemical Sterilization of “Critical Objects”
Glutaraldehyde (> 2.0%) Hydrogen peroxide-HP (7.5%) Peracetic acid-PA (0.2%) HP (1.0%) and PA (0.08%) HP (7.5%) and PA (0.23%) Glut (1.12%) and Phenol/phenate (1.93%) _______________________________________________ Exposure time per manufacturers’ recommendations 2007

Processing “Semicritical” Patient Care Objects
Classification: Semicritical objects come in contact with mucous membranes or skin that is not intact. Object: Free of all microorganisms except high numbers of bacterial spores. Level germicidal action:Kills all microorganisms except high numbers of bacterial spores. Examples: Respiratory therapy and anesthesia equipment, GI endoscopes, thermometer, etc. Method: High-level disinfection 2007

Semicritical Items Endoscopes Respiratory therapy equipment
Anesthesia equipment Endocavitary probes Tonometers Diaphragm fitting rings 2007

High Level Disinfection of “Semicritical Objects”
Exposure Time > 12 m-30m, 20oC Germicide Concentration_____ Glutaraldehyde > 2.0% Ortho-phthalaldehyde (12 m) % Hydrogen peroxide* % Hydrogen peroxide and peracetic acid* %/0.08% Hydrogen peroxide and peracetic acid* %/0.23% Hypochorite (free chlorine)* ppm Glut and phenol/phenate** %/1.93%___ *May cause cosmetic and functional damage; **efficacy not verified 2007

Processing “Noncritical” Patient Care Objects
Classification: Noncritical objects will not come in contact with mucous membranes or skin that is not intact. Object: Can be expected to be contaminated with some microorganisms. Level germicidal action:Kill vegetative bacteria, fungi and lipid viruses. Examples: Bedpans; crutches; bed rails; EKG leads; bedside tables; walls, floors and furniture. Method: Low-level disinfection 2007

Low-Level Disinfection for “Noncritical” Objects
Exposure time > 1 min Germicide Use Concentration Ethyl or isopropyl alcohol 70-90% Chlorine 100ppm (1:500 dilution) Phenolic UD Iodophor UD Quaternary ammonium UD _____________________________________ UD=Manufacturer’s recommended use dilution 2007

Disinfectants for Surface Disinfection
Noncritical Surfaces Medical equipment surfaces (BP cuff, stethoscopes) May frequently become contaminated with patient material Repeatedly touched by health care personnel Disinfectant/detergent should be used Housekeeping surfaces (bed rails, bedside tables) May play a theoretical but less significant role in diseases transmission Disinfectants/detergents may be used (II) and detergents (non-patient care areas) 2007

Use of Disinfectants for Noncritical Items/Surfaces
Disinfect noncritical medical equipment with disinfectant at the proper use-dilution and a contact time of at least 1 min Frequency for disinfecting items/surfaces should comply with facility policies and minimally when visibly soiled and on a regular basis Disinfect noncritical patient-care items if used on a patient on Contact Precautions before use by another patient 2007

Sterilization and Disinfection of Patient Care Items

Critical Instruments Penetrate mucous membranes or contact bone, the bloodstream, or other normally sterile tissues (of the mouth) Heat sterilize between uses or use sterile single-use, disposable devices Examples include surgical instruments, scalpel blades, periodontal scalers, and surgical dental burs There are three categories of patient-care items depending on their intended use and the potential risk of disease transmission. Critical items penetrate soft tissue or contact bone, the bloodstream, or other normally sterile tissues of the mouth. They have the highest risk of transmitting infection and should be heat-sterilized between patient uses. Alternatively, use sterile, single-use disposable devices. Examples include surgical instruments, periodontal scalers, scalpel blades, and surgical dental burs. 2007

Semi-critical Instruments
Contact mucous membranes but do not penetrate soft tissue Heat sterilize or high-level disinfect Examples: Dental mouth mirrors, amalgam condensers, and dental handpieces Semi-critical items contact only mucous membranes and do not penetrate soft tissues. As such, they have a lower risk of transmission. Because most items in this category are heat-tolerant, they should be heat sterilized between patient uses. For heat-sensitive instruments, high-level disinfection is appropriate. Examples of semi-critical instruments include dental mouth mirrors, amalgam condensers, and impression trays. Dental handpieces are a special case. Even though they do not penetrate soft tissue, it is difficult for chemical germicides to reach the internal parts of handpieces. For this reason, they should be heat sterilized using a steam autoclave or chemical vapor sterilizer. 2007

Noncritical Instruments and Devices
Contact intact skin Clean and disinfect using a low to intermediate level disinfectant Examples: X-ray heads, facebows, pulse oximeter, blood pressure cuff Noncritical instruments and devices only contact intact (unbroken) skin, which serves as an effective barrier to microorganisms. These items carry such a low risk of transmitting infections that they usually require only cleaning and low-level disinfection. If using a low-level disinfectant, according to OSHA, it must have a label claim for killing HIV and HBV. However, if an item is visibly bloody, it should be cleaned and disinfected using an intermediate-level disinfectant before use on another patient. Examples of instruments in this category include X-ray head/cones, facebows, pulse oximeter, and blood pressure cuff. 2007

Instrument Processing Area
Use a designated processing area to control quality and ensure safety Divide processing area into work areas Receiving, cleaning, and decontamination Preparation and packaging Sterilization Storage Most instrument cleaning, disinfecting, and sterilization should occur in a designated central processing area to control both quality and personnel safety. To prevent cross-contamination, the instrument processing area should be physically or spatially divided into regions for cleaning, packaging, sterilization, and storage. In the cleaning area, reusable contaminated instruments are received, sorted, and cleaned. The packaging area is for inspecting, assembling, and packaging clean instruments in preparation for final sterilization. The sterilization and storage area contains the sterilizers and related supplies, incubators for analyzing spore tests (if performed in office—although some states require using a testing service), and can contain enclosed storage for sterile items and disposable (single-use) items. 2007

Automated Cleaning Ultrasonic cleaner Instrument washer
Washer-disinfector Cleaning is the basic first step in all decontamination processes. Cleaning involves the physical removal of debris and reduces the number of microorganisms on an instrument or device. If visible debris or organic matter is not removed, it can interfere with the disinfection or sterilization process. Automated or mechanical cleaning equipment, such as ultrasonic cleaners, instrument washers, and washer-disinfectors, are commonly used to clean dental instruments. Automated cleaners increase the efficiency of the cleaning process and reduce the handling of sharp instruments. After cleaning, instruments should be rinsed with water to remove chemical or detergent residue. Photo credit: Chris Miller, PhD, Indiana University School of Dentistry. 2007

Manual Cleaning Soak until ready to clean
Wear heavy-duty utility gloves, mask, eyewear, and protective clothing If manual cleaning is necessary, soak instruments in a rigid container filled with detergent, disinfectant/detergent, or an enzymatic cleaner. This step prevents drying of patient material and makes cleaning easier and less time consuming. Do not use high-level disinfectants/sterilants (e.g., glutaraldehyde) as instrument-holding solutions. To avoid injury from sharp instruments, personnel should wear puncture-resistant, heavy-duty, utility gloves (i.e., not patient care gloves) when handling or manually cleaning contaminated instruments and devices. To protect against splashes, a facemask, eye protection or face shield, and a gown or jacket should be worn. Photo credit: Lt. Col. Jennifer Harte, U.S.A.F. Dental Investigation Service, Great Lakes, IL. 2007

Preparation and Packaging
Critical and semi-critical items that will be stored should be wrapped or placed in containers before heat sterilization Hinged instruments opened and unlocked Place a chemical indicator inside the pack Wear heavy-duty, puncture-resistant utility gloves After thorough cleaning and drying of instruments, critical and semi-critical instruments that will be stored before use should be wrapped or placed into container systems prior to heat sterilization. This step protects items from contamination after the sterilization cycle and during storage. Open or unlock hinged instruments so that all surfaces are exposed. Place a chemical indicator inside each wrapped package. If the indicator cannot be seen from the outside, place another indicator (e.g., indicator tape) on the outside of the package. Always wear heavy-duty, puncture-resistant utility gloves while inspecting and packaging instruments. 2007

Heat-Based Sterilization
Steam under pressure (autoclaving) Gravity displacement Pre-vacuum Dry heat Unsaturated chemical vapor There are three types of heat sterilization methods commonly used in dentistry. Steam under pressure (autoclaving). There are two types of tabletop steam autoclaves: In most commonly used gravity displacement sterilizers, steam enters the chamber and unsaturated air is forced out of the chamber through a vent in the chamber wall. In contrast, pre-vacuum sterilizers are fitted with a vacuum pump to create a vacuum in the chamber and ensure air removal from the sterilizing chamber and load before the chamber is pressurized with steam. This method improves the speed and efficiency of the sterilization process. Dry heat sterilizers are either static air (convection or FDA-approved oven type) or forced air (rapid heat-transfer). Unsaturated chemical vapor sterilizers use a proprietary formula of alcohol/formaldehyde. With all of these methods, always use FDA-approved devices and closely follow the manufacturer’s instructions for proper use. 2007

Liquid Chemical Sterilant/Disinfectants
Only for heat-sensitive critical and semi-critical devices Powerful, toxic chemicals raise safety concerns Heat tolerant or disposable alternatives are available Heat-sensitive instruments can be sterilized or high-level disinfected by soaking them in a liquid chemical germicide cleared by the FDA. However, exposure to these powerful and toxic chemicals can be harmful to DHCP and patients if the manufacturer’s instructions for use and safety precautions are not followed precisely. For these reasons, CDC encourages the use of heat-tolerant or disposable alternatives. Photo credit: Col. Shannon Mills, United States Air Force. 2007

Sterilization Monitoring Types of Indicators
Mechanical Measure time, temperature, pressure Chemical Change in color when physical parameter is reached Biological (spore tests) Use biological spores to assess the sterilization process directly Proper monitoring of sterilization procedures should include a combination of process indicators, including the following: Mechanical—involves assessment of cycle time, temperature, and pressure by observing the gauges or displays on the sterilizer. Chemical—uses sensitive chemicals that change color when a given parameter is reached (e.g., heat-sensitive external tape, internal chemical indicator strip). Biological—this method is the most valid method for monitoring the sterilization process because it assesses the process directly. It does so by using the most heat-resistant microorganisms and not by using indicators that only test the physical and chemical conditions necessary for sterilization. Mechanical and chemical indicators should be assessed with each load. If either mechanical indicators or internal or external chemical indicators indicate inadequate processing, items in the load should not be used until reprocessed. Biological indicators should be assessed at least once a week. 2007

Storage of Sterile and Clean Items and Supplies
Use date- or event-related shelf-life practices Examine wrapped items carefully prior to use When packaging of sterile items is damaged, re-clean, re-wrap, and re-sterilize Store clean items in dry, closed, or covered containment DHCP have a choice about how they maintain their instrument storage area — either date- or event-related shelf-life practices. In date-related packing, every sterilized package is expiration-dated and the instruments are used on a “first in, first out” basis. In event-related practice, the contents of a sterilized package should remain sterile indefinitely unless some event, for example, torn or wet packaging material, causes it to become potentially contaminated. It is still useful to place the date of sterilization and identify the sterilizer used if multiple sterilizers are utilized in the office. In case of sterilization failure, this information would facilitate retrieval of processed items. Examine each package. If it is damaged in any way, items should be re-cleaned, re-wrapped, and re-sterilized. Even if an event-related approach is used, all packages should be labeled with the date of sterilization and which sterilizer was used, should a sterilization failure occur. Store all sterile and clean items and supplies in dry, closed, or covered cabinets. 2007

Environmental Infection Control

Environmental Surfaces
May become contaminated Not directly involved in infectious disease transmission Do not require as stringent decontamination procedures Environmental surfaces can become contaminated with microorganisms during patient care, although they have not been associated directly with disease transmission to patients or DHCP. Environmental surfaces do not require decontamination procedures as stringent as those used on patient care items. 2007

Categories of Environmental Surfaces
Clinical contact surfaces High potential for direct contamination from spray or spatter or by contact with DHCP’s gloved hand Housekeeping surfaces Do not come into contact with patients or devices Limited risk of disease transmission There are two categories of environmental surfaces. Clinical contact surfaces have a high potential for direct contamination from patient materials either by direct spray or spatter generated during dental procedures or by contact with DHCP’s gloved hand. These surfaces can later contaminate other instruments, devices, hands, or gloves. Housekeeping surfaces do not come into contact with patients or devices used in dental procedures. Therefore, they have a limited risk of disease transmission. 2007

Clinical Contact Surfaces
This slide shows some examples of clinical contact surfaces, including a light handle, countertop, bracket tray, dental chair, and door handle (shown by arrows). Photo credit: Lt. Col. Jennifer Harte, U.S.A.F. Dental Investigation Service, Great Lakes, IL. 2007

Housekeeping Surfaces
Examples of housekeeping surfaces are walls, sinks, and floors (shown by arrows). Photo credit: Lt. Col. Jennifer Harte, U.S.A.F. Dental Investigation Service, Great Lakes, IL. 2007

General Cleaning Recommendations
Use barrier precautions (e.g., heavy-duty utility gloves, masks, protective eyewear) when cleaning and disinfecting environmental surfaces Physical removal of microorganisms by cleaning is as important as the disinfection process Follow manufacturer’s instructions for proper use of EPA-registered hospital disinfectants Do not use sterilant/high-level disinfectants on environmental surfaces Use appropriate protective barriers such as heavy-duty utility gloves, masks, and protective eyewear when cleaning and disinfecting surfaces. In general, cleaning and removal of microorganisms is as important as the disinfection process itself. Blood or other patient materials left on surfaces can interfere with the disinfecting process. Follow the manufacturer’s instructions for proper storage, dilution, and use of hospital disinfectants. Because of their toxic nature, the use of sterilants or high-level disinfectants on environmental surfaces is NOT recommended. 2007

Cleaning Clinical Contact Surfaces
Risk of transmitting infections greater than for housekeeping surfaces Surface barriers can be used and changed between patients OR Clean then disinfect using an EPA-registered low- (HIV/HBV claim) to intermediate-level (tuberculocidal claim) hospital disinfectant Because clinical contact surfaces come into direct contact with contaminated gloves, instruments, spray or spatter, their risk of transmitting infection is greater than for housekeeping surfaces. These surfaces can subsequently contaminate other instruments, devices, hands, or gloves. Surface barriers can be used to protect clinical contact surfaces and changed between patients. Surface barriers are particularly useful for surfaces that are hard to clean, such as switches on dental chairs. This practice will also reduce exposure to harmful chemical disinfectants. If surface barriers cannot be used, clean and then disinfect the surface with an EPA-registered hospital disinfectant effective against HIV and HBV (low-level disinfectant). If the surface is visibly contaminated with blood or other patient material, clean and then disinfect the surface with an EPA-registered hospital disinfectant with a tuberculocidal claim (intermediate-level disinfectant). 2007

Cleaning Housekeeping Surfaces
Routinely clean with soap and water or an EPA-registered detergent/hospital disinfectant routinely Clean mops and cloths and allow to dry thoroughly before re-using Prepare fresh cleaning and disinfecting solutions daily and per manufacturer recommendations Housekeeping surfaces carry the least risk for transmitting infections in dental settings. On a routine basis, these surfaces should be either cleaned with soap and water or an EPA-registered detergent/hospital disinfectant. Wet mops and cloths may become contaminated with microorganisms, so clean the mop and cloths after use and allow them to dry thoroughly before re-using. Prepare fresh cleaning and disinfecting solutions daily and per manufacturer recommendations. 2007

Medical Waste Medical Waste: Not considered infectious, thus can be discarded in regular trash Regulated Medical Waste: Poses a potential risk of infection during handling and disposal There is no evidence that traditional medical waste management has contributed to increased levels of disease in the community or among health care personnel. The majority of waste generated in a medical or dental office (~98%–99%) is not considered infectious and can be discarded in the regular trash. Examples include used gloves, masks, and lightly bloodied gauze. Some waste, such as used needles, extracted teeth, and gauze soaked in blood, may pose a potential risk of infection, however, and warrants special precautions during handling and disposal. Follow federal, state, and local regulations for proper treatment and disposal. 2007

Regulated Medical Waste Management
Properly labeled containment to prevent injuries and leakage Medical wastes are “treated” in accordance with state and local EPA regulations Processes for regulated waste include autoclaving and incineration Regulated medical waste requires careful containment for treatment or disposal. A single leak-resistant biohazard bag is usually adequate to contain non-sharp, regulated medical waste. Puncture-resistant containers with a biohazard label, such as sharps containers, are used as containment for scalpel blades, needles, syringes, and unused sterile sharps. Medical waste, both nonregulated and regulated, should be stored and disposed of in accordance with federal, state, and local EPA regulations. Treatment of regulated waste can involve on-site or off-site autoclaving and incineration. Never include extracted teeth with amalgam in regulated waste when disposed by one of these methods. Photo credit: NIOSH Web site. 2007

Monitoring Options Water testing laboratory
In-office testing with self-contained kits Follow recommendations provided by the manufacturer of the dental unit or waterline treatment product for monitoring water quality Monitoring of dental water quality may be performed using commercial self-contained test kits or commercial water-testing laboratories. In-office water-testing systems are available that work at room temperature using small paddles or plates of culture medium to reveal bacterial colonies after 72 or more hours. Dentists should consult with the manufacturer of their dental unit or water delivery system to determine the best method for maintaining acceptable water quality (i.e., <500 CFU/mL) and the recommended frequency of monitoring. 2007

Parenteral Medications
Definition: Medications that are injected into the body Cases of disease transmission have been reported Handle safely to prevent transmission of infections Parenteral medications are medications that are injected into the body. Cases of disease transmission following improper administration of parenteral medications have been reported in medical settings. For this reason it is critical that DHCP handle parenteral medications safely and use special precautions to prevent infection transmission. 2007

LOW LEVEL DISINFECTANTS
PHENOLIC DISINFECTANTS: Effective against bacteria (gram+) and enveloped viruses Not effective against nonenveloped viruses and spores Active in the presence of organic material Used for decontamination of hospital environment Not recommended for semicritical items 2007

LOW LEVEL DISINFECTANTS
QUARTERNARY AMMONIUM COMPOUNDS: Widely used as disinfectants Contraindicated as antiseptics Not effective against nonenveloped viruses, fungi and bacterial spores Commonly used in ordinary environment sanitation of noncritical surfaces 2007

INTERMEDIATE LEVEL DISINFECTANTS
ALCOHOLS Ethyl alcohol Isopropyl alcohol Rapidly bactericidal against against vegetative forms of bacteria Effective against M. tuberculosis, fungi, enveloped viruses 2007

ALCOHOLS Optimum bactericidal concentration is % in water Commonly used topical antiseptics (hand) Also used to disinfect the surface of medical equipment May not penetrate organic material Flammable, irriates tissue, expensive for general use 2007

HYPOCHLORITES Most widely used of the chlorine disinfectants Most common product is 4-6 % sodium hypochlorite Inexpensive and fast acting May produce skin and ocular irritation or gis burns Corrosive to metals in high concent, inactivated by organic material Release toxic chlorine gas when mixed with ammonia or acid 2007

HYPOCHLORITES Eliminate enveloped and non envelopedviruses Effective against fungi, bacteria, algae, but not spores Broad spectrum of antimicrobial activity Most recommended for decontamination of hepatitis and HIV viruses Used as solution in water ( ppm) 2007

IODINE AND IODOPHOR Formulations in soaps (surgical scrubs) Bactericidal, sporicidal, virucidal, fungicidal Require a prolonged contact time Is neutralized in the presence of organic material Frequent application needed Irrigate tissues, corrosive Used for disinfection of some medical equipment (not silicone catheters) 2007

HIGH LEVEL DISINFECTANTS
HYDROGEN PEROXIDE Often used as antiseptic to clean wounds Greatest effect against anaerobic bacteria Effective against a broad range of pathogens Damage tissues in high concentrations Provides high levelof disinfection in 5 min May be blended with iodophors, quarterner ammonia, paracetic acid 2007

GLUTERALDEHYDE Has a wide germicidal spectrum Used as disinfectant or sterilant Highly toxic Only used in a well ventilated setting 2007

FORMALDEHYDE Used as disinfectant or sterilant Sold and used as a water-based solution called formalin Has a wide range spectrum of effect Potential carcinogen, require limited direct contact Limited use for irritating fumes and the pungent odor 2007

ORTHO-PHYTHALDEHYDE (OPA) Similar to gluteraldehyde Has potential advantage compare to glu Has excellent stability Not irritant to eyes, not smell Excellent material compatibility Stains proteins gray (skin) Must be handled with caution 2007

PERACETIC ACID Rapid acts against all organisms No harmful, leaves no residue Remains effective in the presence of organic matter Can corrode some metals Used in automated machines 2007

TUS 2013 Aşağıdaki kimyasal maddelerden hangisi, sterilizasyon amacıyla kullanılmaz? A) Glutaraldehit B) Benzalkonyum klorid C) Etilen oksit D) Formaldehit E) Hidrojen peroksit 2007

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