STERILIZATION & DISINFECTION

1. STERILIZATION& DISINFECTION

2. STERILIZATION Any process that eliminates (removes) or kills all forms of life, including transmissible agents (such as fungi, bacteria, viruses, spore forms, etc.) present on a surface, contained in a fluid, in medication or in biological culture media.Sterilization can be achieved by applying the proper combinations of heat, chemicals, irradiation, high pressure, and filtration.

3. DISINFECTION Disinfectants are substances that are applied to non-living objects to destroy microorganisms that are living on the objects.Disinfection does not necessarily kill all microorganisms, especially nonresistant bacterial spores; it is less effective than sterilisation, which is an extreme physical and/or chemical process that kills all types of life.. Unlike sterilization, disinfection is not sporicidal

4. A few disinfectants will kill spores with prolonged exposure times (3–12 hours); these are called chemical sterilants. At similar concentrations but with shorter exposure periods (e.g., 20 minutes for 2% glutaraldehyde), these same disinfectants will kill all microorganisms except large numbers of bacterial spores; they are called high-level disinfectants.

5. Chemical Sterilants • >2.4% glutaraldehyde-based formulations • 0.95% glutaraldehyde with 1.64% phenol • 7.5% stabilized hydrogen peroxide • 7.35% hydrogen peroxide with 0.23% peracetic acid • 0.2% peracetic acid • 0.08% peracetic acid with 1.0% hydrogen peroxide. Liquid chemical sterilants reliably produce sterility only if cleaning precedes treatment and if proper guidelines are followed regarding concentration, contact time, temperature, and pH.

6. 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.

7. Antisepsis-when a disinfectant is applied to a living tissue. Decontamination removes pathogenic microorganisms from objects so they are safe to handle, use, or discard.

8. METHODS OF STERILIZATION • HEAT STERLIZATION • RADIATION STERLIZATION • CHEMICAL STERLIZATION

9. 1.HEAT STERLIZATION DRY HEAT MOIST HEAT • INCINERATION • RED HEAT • FLAMING • HOT AIR OVEN • AUTOCLAVING(steam above 100degC) • BOILING WATER(steam at atmospheric pressure)

10. 2.RADIATION STERILIZATION 3.CHEMICAL STERILIZATION • UV RAYS • GAMMA RAYS • FORMALDEHYDE • GLUTARALDEHYDE • HYDROGEN PEROXIDE • ALCOHOLS • BLEACHING AGENTS • PER ACETIC ACID • CHLORINE AND ITS COMPOUNDS • IODOPHORES • PERACETIC ACID AND HYDROGEN PEROXIDE

11. METHODS OF DISINFECTION

12. Factors Affecting The Efficacy Of Disinfection And Sterilization

13. 1.Number and Location of Microorganisms the larger the number of microbes, the more time a germicide needs to destroy all of them. scrupulous cleaning of medical instruments before disinfection and sterilization.

14. 2.Innate Resistance of Microorganisms • Intrinsic resistance mechanisms in microorganisms to disinfectants vary. For example, spores are resistant to disinfectants because the spore coat and cortex act as a barrier & mycobacteriahave a waxy cell wall that prevents disinfectant .Implicit in all disinfection strategies is the consideration that the most resistant microbial subpopulation controls the sterilization or disinfection time. That is, to destroy the most resistant types of microorganisms (i.e., bacterial spores), the user needs to employ exposure times and a concentration of germicide needed to achieve complete destruction

15. 3.Concentration and Potency of Disinfectants • The more concentrated the disinfectant, the greater its efficacy and the shorter the time necessary to achieve microbial kill. 4.Physical & chemical factors • The activity of most disinfectants increases as the TEMPERATURE increases, but too great an increase in temperature causes the disinfectant to degrade and weakens its germicidal activity and thus might produce a potential health hazard.

16. 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 disinfectants/sterilants, such as EtO, chlorine dioxide, and formaldehyde. • WATER HARDNESS (i.e., high concentration of divalent cations) reduces the rate of kill of certain disinfectants because divalent cations (e.g., magnesium, calcium) in the hard water interact with the disinfectant to form insoluble precipitates.

17. 5.ORGANIC MATTER serum, blood, pus, or fecal or lubricant material can interfere with the antimicrobial activity by:: As interference occurs by a chemical reaction between the germicide and the organic matter resulting in a complex that is less germicidal or nongermicidal, leaving less of the active germicide available for attacking microorganisms. Chlorine and iodine disinfectants, in particular, are prone to such interaction

18. 6.DURATION OF EXPOSURE • Items must be exposed to the germicide for the appropriate minimum contact time. • All lumens and channels of endoscopic instruments must contact the disinfectant. • Air pockets interfere with the disinfection process, and items that float on the disinfectant will not be disinfected. • The disinfectant must be introduced reliably into the internal channels of the device. • MCT varies..but longer better than shorter.

19. 7.BIOFILMS • 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 by multiple mechanisms, including physical characteristics of older biofilms, genotypic variation of the bacteria, microbial production of neutralizing enzymes, and physiologic gradients within the biofilm (e.g., pH). • Bacteria within biofilms are up to 1,000 times more resistant to antimicrobials than are the same bacteria in suspension.

20. Hypochloritescan effectively inactivate biofilm bacteria. •  Their presence can have serious implications for immunocompromised patients and patients who have indwelling medical devices. • No products are EPA-registered or FDA-cleared for this purpose.

21. High Level Disinfection Complete elimination of all microorganisms in or on an instrument, except for small numbers of bacterial spores. The FDA definition of high-level disinfection is a sterilant used for a shorter contact time to achieve a 6-log10 kill of an appropriate Mycobacterium species. Cleaning followed by high-level disinfection should eliminate enough pathogens to prevent transmission of infection.

22. Chemical Sterilants.. • >2.4% glutaraldehyde-based formulations • 0.95% glutaraldehyde with 1.64% phenol • 7.5% stabilized hydrogen peroxide • 7.35% hydrogen peroxide with 0.23% peracetic acid, • 0.2% peracetic acid, and • 0.08% peracetic acid with 1.0% hydrogen peroxide. • Liquid chemical sterilants reliably produce sterility only if cleaning precedes treatment and if proper guidelines are followed regarding concentration, contact time, temperature, and pH.

23. MOST COMMONLY USED:: • AUTOCLAVING • CHEMICAL METHODS

24. DISINFECTION OF OPERATION THEATRE

25. 2 steps:: 1.Cleaning with carbolic acid 2.Fumigation- -with HCHO vapours -with aldehyde based germicides -Silver & hydrogen peroxide

26. 1.FUMIGATION WITH HCHO VAPOURS • Floor is cleaned with warm water,detergent and 5% sodium hypochlorite or 3% phenol followed by fumigation. • Seal the room with adhesive tape applied round the edges of doors,windows and ventilator apertures,etc • .For each 1000 cubic feet of space place 5000 ml of HCHO solution and 1000 ml of water in an electric boiler with a safety cut out when boiling dry and a time switch.Set the latter to open just before the evaporation is completed. • Switch on the boiler,leave the room filled with HCHO and seal the door for 24hours • Then open the doors and windows to allow vapours to disperse and neutralize any residual HCHO with ammonia by exposing 250ml of SG ammonia per litre of formalin used. • CONVENTIONAL METHOD

28. CARBOLIZATION(Carboxyl acid) & FUMIGATION with Formaldehyde Advantages – Established age old technique Cost effective Disadvantages – a. Carboxylic acid has efficacy as scouring and disinfecting agent b. Time consuming, min 24 hrs turn around time c. Self defeating – OT fumigated with Formaldehyde needs to be force de-aired with unclean air d. Unsafe Formaldehyde is carcinogenic

29. HAZARDS OF HCHO::-mutagenic & carcinogenic • Irritable to eyes,nose & mucous membranes • Asthma attacks can be precipitated. • Breathing difficulties.

30. 2.Fumigation with aldehyde based germicides:: Glutaraldehyde & formaldehyde (200 ml in 10 liters of water i.e 2%) through fogging machine is the commonly used procedure. Advantages- Effective Disadvantages – a. Leaves sticky residue because of surfactant base b. Self defeating – OT fumigated with Formaldehyde needs to be force de-aired with unclean air c. Unsafe- Formaldehyde has been identified as a carcinogen

31. Silver (Ag) and Hydrogen Peroxide (H2O2) • Advantages – a. Has deep penetrating capability • b. Has no known resistant strains • c. Effective against Bacteria, Viruses, • Mycobacteria, Amoeba, Fungi and • spore forming organisms • NEW METHOD

32. A fogging system Droplets~7microns thrust by a motor running at 20,000 RPM to a distance of 15 m Solution Ecoshield– 11% Hydrogen Peroxide and 0.01% dilute sliver nitrate

33. NEW METHOD:: FUMIGATION WITH ECOSHIELD:: • Brand name. • Marketed by Johnson and Johnson. • A solution based on stabilised hydrogen peroxide with silver nitrate. It has been seen to be effective against bacteria, virus, fungi, protozoa, mycobacteria, bacteriophages and biofilms. • Works best with an ultra low volume fogger that releases droplets of seven to 20 microns. It traps suspended particulate matters and kills the microorganisms. • cost-effective option that could be used by hospitals that do not have sophisticated filtering systems like the high efficiency particulate air filter or laminar filter.

35. Ecoshield helps disinfect operations theatres within two hours. This can ensure a quicker turnaround time. • HCHO takes upto24 hours and is a known irritant,mutagenic and carcinogenic.

36. AT HIHT:: • Fumigation with ecoshield • Routinely,at the end of the day. • Normally,3-4 noninfected cases can be performed in an o.t. sterlized once by fumigation.

37. BUT in infected cases (HIV +ve,HbsAg +ve..) • Immediate fumigation of the OT is done after the operation • All disposables are discarded.

38. A Rational Approach To Disinfection And Sterilization EH Spaulding believed that how an object will be disinfected depended on the object’s intended use. CRITICAL- objects which enter normally sterile tissue or the vascular systemor through which blood flows should be sterile. SEMICRITICAL- objects that touch mucous membranes or skin that is not intactrequire 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-leveldisinfection (or non-germicidal detergent).

39. Critical 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, cardiac and urinary catheters, implants, andultrasound probes used in sterile body cavities; etc. Method: Steam, gas, hydrogen peroxide plasma, ozone or chemical sterilization.

40. Sterilization of “Critical Objects” Steam sterilization Hydrogen peroxide gas plasma Ethylene oxide Peracetic acid-chemical sterilization Ozone Vaporized hydrogen peroxide Steam formaldehyde

41. 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

42. “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. Germicidal action: kills allmicroorganisms except high numbers of bacterial spores. Examples: Respiratory therapy and anesthesia equipment, GI endoscopes, endocavitary probes, etc. Method: High-level disinfection

43. Semicritical Items • Endoscopes • Respiratory therapy equipment • Anesthesia equipment • Endocavitary probes • Tonometers • Diaphragm fitting rings

44. High Level Disinfection of “Semicritical Objects” Exposure Time > 12 m-30m, 20oC Germicide Concentration_____ Glutaraldehyde> 2.0% Ortho-phthalaldehyde (12 m) 0.55% Hydrogen peroxide* 7.5% Hydrogen peroxide and peracetic acid* 1.0%/0.08% Hydrogen peroxide and peracetic acid* 7.5%/0.23% Hypochlorite (free chlorine)* 650-675 ppm Glut and phenol/phenate** *May cause cosmetic and functional damage; **efficacy not verified

45. “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 (or detergent for housekeeping surfaces)

46. Low-Level Disinfection for “Noncritical” Objects Exposure time > 1 min Ethyl or isopropyl alcohol Chlorine Phenols Iodophores Accelerated hydrogen peroxide _________________________________________________

47. Items must be cleaned using water with detergents or enzymatic cleaners before processing. • Cleaning reduces the bioburden and removes foreign material (organic residue and inorganic salts) that interferes with the sterilization process. • Cleaning and decontamination should be done as soon as possible after the items have been used as soiled materials become dried onto the instruments.

48. Rinsing endoscopes and flushing channels with sterile water, filtered water, or tap water will prevent adverse effects associated with disinfectant retained in the endoscope (e.g., disinfectant-induced colitis) • Items can be rinsed and flushed using sterile water after high-level disinfection to prevent contamination with organisms in tap water, such as nontuberculousmycobacteria,Legionella or gram-negative bacilli such as Pseudomonas. • Alternatively, a tapwater or filtered water (0.2m filter) rinse should be followed by an alcohol rinse. After rinsing, items should be dried and stored (e.g., packaged) in a manner that protects them from recontamination.

49. Noncritical items • Intact skin acts as an effective barrier to most microorganisms; therefore, the sterility of items coming in contact with intact skin is "not critical. • Most noncritical reusable items may be decontaminated where they are used and do not need to be transported to a central processing area. 

50. Noncritcal environmental surfaces include • bed rails, • food utensils, • bedside tables, • patient furniture and • floors. Noncritical environmental surfaces frequently touched by hand (e.g., bedside tables, bed rails) potentially could contribute to secondary transmission by contaminating hands of health-care workers or by contacting medical equipment that subsequently contacts patients . • Mops and reusable cleaning cloths are regularly used to achieve low-level disinfection.  The water-disinfectant mixture should be changed regularly (e.g., after every three to four rooms, at no longer than 60-minute intervals), the mopping procedure actually can spread heavy microbial contamination throughout the health-care facility .