Cleaning and sterilization

infection control

1. Cleaning, Disinfection, and Sterilization Prepared by Dr.Hanadi Albasha

2. sterilization referring to any process that eliminates (removes) or kills (deactivates) all forms of life and other biological agents which consider pathogens  Sterilization can be achieved with one or more of the following : heat, chemicals, irradiation, high pressure, and filtration.

3. Goals of sterilization Render medical devices safe for patient use Prevent infections Minimize potential for infection Prevent cross contamination Provide consistent sterile processing procedures

4. disinfection Disinfection describes a process that eliminates many or all pathogenic microorganisms with the exception of bacterial spores .

5. decontamination & cleaning Cleaning is the removal of visible soil (e.g., organic and inorganic material) from objects and surfaces and normally is accomplished manually or mechanically using water with detergents or enzymatic products. Thorough cleaning is essential before high-level disinfection and sterilization because inorganic and organic materials that remain on the surfaces of instruments interfere with the effectiveness of these processes. Decontamination removes pathogenic microorganisms from objects so

6.  Instruments and items for patient care were divided into three categories based on the degree of risk of infection involved in the use of the items: Critical: enters sterile tissue and must be sterile Semi-critical: contacts mucous membranes and requires high-level disinfection Noncritical : comes in contact with intact skin and requires low-level disinfection

7. Methods of sterilization

8. Process Level of Microbial Inactivation Method Examples (with processing times) Healthcare Application (examples) Sterilization Destroys all microorganisms, including bacterial spores High temperature Steam (~40 min) Heat-tolerant critical (surgical instruments) and semicritical patient-care items Low temperature Ethylene oxide gas (~15 hr ), hydrogen peroxide gas plasma (28-52 min), ozone (~4 hr ), hydrogen peroxide vapor (55 min) Heat-sensitive critical and semicritical patient-care items Liquid immersion Chemical sterilants hydrogen peroxide 7.5% HP (6 hr ) >2% glutaraldehyde (~10 hr ) Heat-sensitive critical and semicritical patient-care items that can be immersed

9. Process Level of Microbial Inactivation Method Examples (with processing times) Healthcare Application (examples) High-level disinfection (HLD) Destroys all microorganisms except high numbers of bacterial spores Liquid immersion 0.55% OPA (12 min) >2% glutaraldehyde (10-90 min) Heat-sensitive semicritical items (e.g., GI endoscopes, bronchoscopes, endocavitary probes) Intermediate-level disinfection Destroys vegetative bacteria, mycobacteria, most viruses, most fungi but not bacterial spores Liquid contact EPA-registered hospital disinfectant with label claim regarding tuberculocidal activity (e.g., chlorine-based products, phenolics , improved hydrogen peroxide-exposure times at least 1 min) Noncritical patient care item (blood pressure cuff) or surface with visible blood Low-level disinfection Destroys vegetative bacteria, some fungi and viruses but not mycobacteria or spores Liquid contact EPA-registered hospital disinfectant with no tuberculocidal claim (e.g., chlorine-based products, phenolics, improved hydrogen peroxide, quaternary ammonium compounds-exposure times at least 1 min) or 70-90% alcohol Noncritical patient care item (blood pressure cuff) or surface (bedside table) with no visible blood

10. Physical Methods There are several physical sterilization methods, the most efficient of which combines heat with humidity and pressure in a device called an autoclave. Autoclave Steam Sterilization is suited for objects that can tolerate humidity, high pressure (1 to 3.5 atmospheres above ambient), and high temperature (+121°C to +148°C). Typical examples are surgical instruments.  The entire cycle can take from 15 to 60 minutes.

11. a. Chemical Indicators Chemical Color Change Indicators Chemical indicators for steam autoclaving change colors after being exposed for a few minutes to normal autoclave operating temperatures of 121ºC . Chemical indicators should be positioned near the center of each load, and toward the bottom front of the autoclave. Caution:  Most chemical indicators can only be used to verify that your autoclave has reached normal operating temperatures for decontamination; they have no time factor. Chemical indicators alone are not designed to prove that organisms are actually killed during a decontamination cycle. b. Biological Indicators Biological indicators are designed to demonstrate that an autoclave is capable of killing microorganisms. Follow the manufacturer’s instructions for the spore test. This test must be performed at least every 90 days.

12. Chemical methods a. Aldehydes: Ortho- phthalaldehyde (OPA) An essential component of disinfection of reusable devices ( e.G. , Endoscopes). The time required for high-level disinfection of a medical device by OPA would be less than 12 minutes. Glutaraldehyde ( cidex )  high-level disinfectant and chemical sterilant is used most commonly as a high-level disinfectant for medical equipment such as endoscopes  spirometry tubing, dialyzers ,transducers, anesthesia and respiratory therapy equipment, hemodialysis systems and reuse of laparoscopic disposable plastic trocars . Glutaraldehyde is noncorrosive to metal and does not damage lensed instruments, rubber. or plastics. Glutaraldehyde should not be used for cleaning noncritical surfaces because it is too toxic and expensive.

13. b. Halogen-Based Biocides: (Chlorine Compounds and Iodophores ) Chlorine Compounds Chlorine compounds are good disinfectants on clean surfaces, but are quickly inactivated by organic matter and thus reducing the biocidal activity. They have a broad spectrum of antimicrobial activity and are inexpensive and fast acting. Hypochlorites ( clorex ), the most widely used of the chlorine disinfectants Because of its oxidizing power, it loses potency quickly and should be made fresh Iodophors Iodophors ( Betadyne , Povidone-Iodine)are used both as antiseptics and disinfectants. An iodophor is a combination of iodine and a solubilizing agent   Both bleach and iodophors should be made up in cold water in order to prevent breakdown of the disinfectant.

14. c. Quaternary Ammonium Compounds : Quaternary ammonium compounds are generally odorless, colorless, nonirritating, and deodorizing. They also have some detergent action, and they are good disinfectants. activity is reduced in the presence of some soaps or soap residues, detergents, acids and heavy organic matter loads. They are generally ineffective against viruses, spores and  Mycobacterium tuberculosis . Basically these compounds are not suitable for any type of terminal disinfection. these compounds are better used in water baths, incubators, and other applications where halide or phenolic residues are not desired.

15. d. Alcohols: Alcohols work through the disruption of cellular membranes, solubilization of lipids, and denaturation of proteins Ethyl and isopropyl alcohols are the two most widely used alcohols for their biocidal activity. These alcohols are effective against some viruses and a broad spectrum of bacterial species, but ineffective against spore-forming bacteria. They evaporate rapidly, which makes extended contact times difficult to achieve unless the items are immersed. The optimum bactericidal concentration for ethanol and isopropanol is in the range of 60% to 90% by volume. Their cidal activity drops sharply when diluted below 50% concentration. Absolute alcohol is also not very effective. They are used to clean instruments and wipe down interior of Biological Safety Cabinets and bottles, etc. to be put into Biological Safety Cabinets. Alcohols are generally regarded as being non-corrosive.

16. e. Acids/Alkalis: Hydrogen Peroxide Works by producing destructive hydroxyl free radicals that can attack membrane lipids, DNA, and other essential cell components Hydrogen peroxide is active against a wide range of microorganisms, including bacteria, yeasts, fungi, viruses, and spores It's used as high-level disinfectant (0.5 %-0.6% ) contact time 30-60 min. Concentrations of hydrogen peroxide from 6% to 25% show promise as chemical sterilants and it has been used in for disinfecting soft contact lenses (e.g., 3% for 2–3 hrs ) , tonometer prisms ,ventilators , fabrics , and endoscopes.