Sterilization and disinfection

STERILIZATION AND DISINFECTION

1. Sterilization and disinfection Presented By: Dr Md Mahbubul Hoda Moderator: Dr Veerendra Kumar

2. CONTENT Introduction Definitions and basics of infection control History Most common infective agents in Maxillofacial regions. Methods of sterilization and disinfection a) By physical agents B) By chemical agents Design and disinfection of operation theater Guidelines for hand scrub , gloves, masks, gowns and foot wear. Waste management References

3. Introduction Significance- Microorganism are ubiquitous. Since they cause contamination, infection and decay, it becomes necessary to remove or destroy them from operating materials and from operating site. Aims- In microbiology- Prevents contamination by extraneous organisms. In surgery- For maintaining asepsis. In food and drug manufacture Ensuring safety from contaminating organisms

4. Definitions and basics of infection control Sterilization- It’s a process by which an article, surface or medium is made free of all microorganisms either in the vegetative or spore form. Disinfection – The destruction or removal of all pathogenic organisms, or organism capable of giving rise to infection.( incapable of destroying spores)

5. Disinfectants are generally classified as follows- High level disinfectants: Chemicals that kill all microorganisms except bacterial spores, when exposed for limited time. Example - 2.4% glutaraldehyde , 7.5% hydrogen peroxide Intermediate level disinfectants: They kill mycobacteria, vegetative bacteria, most viruses and most fungi but do not necessarily kill bacterial spores. Example- Phenol, alcohol .

6. Low level disinfectants: Can kill most vegetative bacteria, some fungi and some viruses. Commonly used detergents and soaps act as low level disinfectants along with their cleaning properties.

7. Instruments and different types of disinfection- (Recommended by Spaulding)- Critical items: These are instruments or objects that are introduced directly into the bloodstream or into other normally sterile areas of the body. Absolute sterility at the time of use is required for these items. Example- S urgical instruments, cardiac and urinary catheters, implants, and needles

8. Semicritical items: These instruments are introduced into body cavities and therefore come into contact with intact mucous membranes, but do not ordinarily penetrate body surfaces. Examples - non invasive flexible and rigid fiber -optic endoscopes, endotracheal tubes, anesthesia breathing circuits, and thermometer. 2% activated glutaraldehyde solution can be used for about a fortnight. The equipment should be kept immersed in glutaraldehyde solution for at least 45 minutes.

9. Non-critical items: These are items that do not ordinarily penetrate, but touch only intact skin. Example - crutches, bed boards, blood pressure cuffs, and a variety of other medical accessories. Simple washing with a detergent may be sufficient .

10. Antisepsis- The term used to indicate the prevention of infection, usually by inhibiting the growth of the bacteria in wounds or in tissue . Antiseptics- chemical disinfectants which can be safely applied to skin or mucous membrane and are used to prevent infection by inhibiting the growth of bacteria. Decontamination- Refers to the process of rendering an article or area free of danger from contaminants,, including microbial, chemical, radioactive and other hazards.

11. Infection control essentially consists of - Cleaning -Disinfection -Sterilization of equipments and environment -Hand hygiene practices -Preoperative preparation of patient and antibiotic prophylaxis

12. Early civilization practised salting, smoking, pickling and exposure to sunlight. Prior to the mid-19th century, gangrene set in before the wound healed Repeated amputations performed in an effort to stop the infection reaching the body, sometimes to no avail. The first reliable method of preventing infection during an operation was developed by Dr. Joseph Lister Cleaning, sterilisation, disinfection are the cornerstones of hospital infection prevention activities. HISTORY

13. HISTORY Louis Pasteur (1822-1895) a trained chemist of France, known as father of microbiology introduce sterilization techniques and development of steam sterilizer, autoclave and hot air oven. Joseph Lister(1827-1912) was a professor of surgery in Glasgow Royal infirmary applied Pasture’s work and introduce antiseptic techniques in surgery(1867) effecting pronounced drop in mortality and morbidity due to surgical sepsis, for this great work he is known as father of antiseptic surgery.

14. Cytomegalovirus Hepatitis B Hepatitis C Herpes simplex virus Human immunodeficiency virus Mycobacterium tuberculosis Staphylococci and streptococci Organisms that are transmitted in a dental setup

15. PHYSICAL METHOD: Sunlight, heat (dry / moist) Filtration. Radiation. CHEMICAL: Alcohols. Aldehyde. Phenols. Halogens Salts. Surface active agents. Dyes. Gases. METHODS

16. Physical agents Sunlight : -Sunlight having antimicrobial properties because of ultraviolet radiation. -It’s a natural source of sterilization .

17. Heat- Heat is considered to be most reliable method of sterilization of articles that can withstand heat . Heat acts by oxidative effects as well as denaturation and coagulation of proteins. Mainly two types of heats are used for sterilization Dry heat Moist heat

18. Dry heat- A cts by protein denaturation , oxidative damage and toxic effects of elevated levels of electrolytes. Red heat : Articles such as bacteriological loops, straight wires, tips of forceps and searing spatulas are sterilized by holding them in Bunsen flame till they become red hot . 2) Flaming : This is a method of passing the article over a Bunsen flame, but not heating it to redness. Articles such as scalpels , mouth of test tubes, flasks, glass slides and cover slips are passed through the flame a few times. Even though most vegetative cells are killed, there is no guarantee that spores too would die on such short exposure.

19. Incineration: This is a method of destroying contaminated material by burning them in incinerator. Articles such as soiled dressings; animal carcasses, pathological material and bedding etc should be subjected to incineration. This technique results in the loss of the article, hence is suitable only for those articles that have to be disposed .

20. 3) Hot air oven- Introduced by Pasteur. Holding period of 160 C for one hour is used to sterile Glassware, forceps, scalpel, scissors, forceps, all glass syringes, swabs, some pharmaceutical products. It consists of a metallic chamber, walls contain heating elements with fan for equal distribution of hot air on objects

21. Holding time 60 minutes at 160 C 40 minutes at 170 C 20 minutes at 180 C Sterilization control- Spores of non toxic strains clostridium tetani are used as a microbiological test of dry heat efficiency Brown tube Thermocouples

22. Moist heat- Moist heat acts by coagulation and denaturation of proteins. At temperature below 100 C – For pasturisation - Holders method – 63 C for 30 minutes Flash method- 72 C for 20 seconds followed by rapid cooling to 13 c By this method all non sporing pathogen such as mycobacterium, brucellae and salmonellae are destroyed.

23. At temperature 100 c- Boiling- Vegetative bacteria are killed almost immediately at 90-100 c for 10-30 minutes , but sporing bacteria requires prolonged period of boiling. Note – Boiling is not recommended for sterilization, because nothing short of autoclaving under pressure can destroy spores and ensure sterilization

24. Steam at atmospheric pressure( 100 c) – An atmosphere of free steam is used to sterilize culture media which may decompose if subjected to higher temperature. Koch or Arnold steamer is usually used.

25. Steam under pressure ( autoclave)- Principle- Water boils when its vapour pressure is equals to surrounding atmospheric pressure, Hence when pressure inside a closed chamber increases, the temperature at which water boils also increases. Saturated steam has penetration power, and when this saturated steam comes into contact with cooler surface it condenses to water and gives up its latent heat to that surface.

26. Equation says – 1600ml steam at 100 c condenses into 1ml of water and releases 518 calories of heat. This large reduction of volume sucks in more steam to the area and the process continues till the temperature of the surface is raised to that of steam . Temperature( C) Holding time (minutes) 121 15 (15 lbs) 126 10 (20 lbs) 134 03 (30 lbs)

27. Materials can be sterilized by autoclave – Dressing, Lab ware, glassware, pharmaceutical products, metal instruments, surgical instruments, cultural media, disposable and non disposable syringes. Sterilization control- Bacillus steriothermophillus are used Chemical indicators Autoclave tapes Thermocouples

28. Filtration- Filtration helps to remove bacteria from heat labile liquids such as sera and solutions of sugars or antibiotics used for culture media. The following types of filters have been used- Candle filter- this type of filter used widely for purification of water for industrial and drinking purpose. its of two types a) Unglazed ceramic filters b) Diatomaceous earth filters

29. 2) Asbestos filters- Are disposable, single use discs. They have high adsorbing capacity and tend to alkalinize filtered liquids, the carcinogenic potential of asbestos has discouraged their use 3) Sintered glass filters- Prepared by heat fusing finely powdered glass particles of graded sizes. They have low absorptive property and can be cleaned easily but are brittle and expensive.

30. 4) Membrane filter- Made of cellulose esters or other polymers have largely replaced other types of filters. They are routinely used in water purification and sterilization and sterility testing and for the preparation of solution of parenteral use.

31. Radiation- Two types of radiation are used for sterilization Nonionising - Infrared and Ultraviolet rays ( low energy type) 2) Ionising – gamma rays and high energy electron ( high energy type)

32. 1) Nonionising radiation – Here electromagnetic rays with wavelength longer than those of visible light are used. These are to a larger extent absorbed as heat, hence infrared radiation can be considered as a form of hot air sterilization Used for – Rapid mass sterilization of prepacked items such as syringes and catheters.

33. While ultraviolet radiation is used for disinfecting enclosed areas such as entry ways, operation theaters and laboratories. 2) Ionization radiation- X-ray, gamma rays and cosmic rays are highly lethal to DNA and other vital constituents. They have very high penetrative power, since there is no appreciable increase in temperature in this method, this is referred to as Cold sterilization Uses- items like plastic syringes, swabs, catheters, oils and metal foils sterilization .

34. Chemical agents The ideal properties of chemical agent should have – - Effective against all microorganisms and have wide spectrum of activity. -Have speedy action. -Effective in the presence of organic matter. -Be stable. -Be effective in varying pH. -Compatible with other antiseptics. -Have high penetrating power. -Not corrode metals. -No cause irritation. -Not interfere with healing. -Not to be toxic if absorbed into circulation. -Be cheap and safe. -Easy available.

35. Chemical agents acts in various ways to micro-organisms- Protein coagulation Disruption of cell membrane resulting in exposure, damage or loss of the contents Removal of the free sulphydryl groups essential for the functioning of the enzymes . Interruption of cellular metabolism by acting as substrate competitors.

36. Alcohol- Ethyl alcohol and isopropyl alcohol are the most frequently used . - Denaturating bacterial proteins (against vegetative bacteria), disrupt cytoplasmic membrane, dissolves lipids. -Rapidly kill T.B bacilli. -No sporicidal / virucidal . -Skin antiseptic (swabbing of skin prior to injection) Methyl alcohol – Against fungal spores, toxic and inflammable .

37. Uses- Rubber stoppers , thermometers, stethoscope, scissors, ventilation bags, external surface of ventilators, electrical equipment's.

38. Aldehydes – There are mainly two types of aldehyde Formaldehyde- - Active against the amino group in the protein, inactivates nucleic acid. - Bactericidal, sporicidal , and virucidal . - Used both in aqueous form and gaseous form. - liquid Formaldehyde used to preserve anatomical specimens, and destroying. - Gas is used for sterilizing instruments and heat sensitive catheters and for fumigating wards

39. FORMALDEHYDE (40% = formalin): to preserve anatomical specimen. 10% +0.5% sodium tetra borate is used to sterilize metal instruments.

40. Glutaraldehyde :- - Similar action like formaldehyde -Effective against pseudomonas, tubercle bacillus, fungi and viruses. -Activated gluteraldehyde 2% is rapid acting, non-staining, and rust inhibiting. -For complete disinfection: immersed for 10 minutes to destroy vegetative pathogens.

41. For sterilization : Immersed for 10 hours at ph 7.5 to 8.5 to destroy pathogenic spores. -Plastic tubes, metal, polythene tubes, platic endotracheal tube, bronchoscope.

42. Dyes – Aniline and Acridine dyes used extensively as skin and wound antiseptics. These dyes are more active against gram positive than gram negative organism . No activity seen against tubercle bacilli and hence used in Lowenstein Jensen medium. They shows lethal effect on bacteria by acting on acidic group.

43. More advanced dyes are Proflavine , Acriflavine , Evaflavine . They slowly release and shows prolonged action on organisms. Acting by impairing the DNA complexes of organism and thus inhibit the multiplication or micro-organisms.

44. Chlorine is used in water supplies, swimming, food / dairy. Bleaching powder, sodium hypochlorite and chloramines are also used (release of free chlorine  react with water  hypochlorous acid). (oxidation / denature). Per-acetic acid – sporicidal used to sterilize equipment. Disinfectant for HIV infected material. Bactericidal, fungicidal, virucidal , sporicidal

45. IODINE: ( 5-10%) Iodine molecules rapidly penetrate the cell wall of microorganisms and inactivate cells by forming complexes with amino acids and unsaturated fatty acids, resulting in impaired protein synthesis and alteration of cell membranes. 2% iodine in 50% alcohol (Tincture) Iodine with surface active agents called iodophores = BETADINE.

46. They have bactericidal activity against gram positive, gram negative, and certain spore forming bacteria (clostridia and bacillus spp ) and also active against mycobacteria , viruses and fungi.

47. Hydrogen peroxide: Damages proteins and DNA of micro- organsim Used at 6%, to decontaminate the instruments, equipments. 3% is used for skin disinfection and deodorising wounds and ulcer. Strong solutions are sporicidal .

48. Phenols- These are obtained by distillisation of coal tar between temperature of 170 C and 270 C. Lister the father of antiseptic surgery, 1 st introduced their use in surgery 1865. Mechanism of action is damage cell membrane and releasing cell contents and causing lysis of cell. Derivatives of phenol are cresol, lysol , chlorhexidine , chloroxylenol , and hexachlorophane .

49. CHLORHEXIDINE: ( savlon ) chlorhexidine gluconate is a commonly used agent and has been incorporated into number of hand hygiene preparation also. It is a cationic bisguanide and acts by disruption of cytoplasmic membrane, resulting in precipitation of celllular contents. It has good activity against gram positve bacteria, some what gram negative bacteria and fungi, and only limited activity against tubercle bacilli. The activity of chlorhexidine minimally affected in presence of organic material such as blood

50. HEXACHLOROPHANE: More against gram positive. Applied over the skin as prophylaxis against staphylococcal. Potentially toxic. CRESOLS – used for infected glass wares, cleaning floors. Not inactivated by presence of organic matter .

51. Gases Ethylene oxide- This is a colourless liquid with a boiling point of 10.7 C At normal temperature and pressure is highly penetrating gas with a sweet ethereal smell. Highly inflammable and in concentration in air greater than 3% highly explosive, by mixing it with carbon dioxide or nitrogen , to a concentration of 10%, its explosive tendency is eliminated

52. Its action is due to alkylating the amiino , carboxyl, hydroxyl and sulphydryl groups in protein molecules, in addition it acts on DNA and RNA too. Its active against all types of microorganisms including viruses and spores. ETO gas sterilization is more expensive and complex process of sterilization , hence it is usually restricted to objects that might be damaged by heat or excessive moisture. Bacillus subtilis niger used to check sterilization completion .

53. It diffuses through many types of porous materials and readily penetrates some plastics. It is specially used for heart-lung machines, respirators, sutures and dental equipments. It is unsuitable for fumigating the wards or room because of its explosive properties.

54. Formaldehyde- Widely used for fumigating wards and rooms and operation theaters. After sealing the windows and other outlets, formaldehyde gas is generated by adding 150g of KMnO 4 to 280ml formalin for every 1000cu ft of room volume . After starting generation of vapour the door should be sealed for 48 hours.

55. Betapropiolactone (BPL) This is a condensation product of ketane and formaldehyde with boiling point 163 C. Though its having low penetrating power, It is said to be more efficient for fumigating purpose than formaldehyde. Its having rapid biocidal action but unfortunately has carcinogenic activity. 0.2% BPL is used for sterilization, is capable to kill all microorganism and very active against viruses.

56. Surface active agents Substances which alter energy relationship at interfaces, producing a reduction of surface or interfacial tension are referred to as surface active agents Used as wetting agents, detergents and emulsifiers. They are classified into four main group - Anionic, cationic, nonionic, amphoteric .

57. Cationic form shows most wide range of antibacterial action. Acts on the phosphate group of the cell membrane and also enter the cell. The membrane loses its semi permeability and the cell proteins are denatured. These are markedly bactericidal being active against gram positive and less active against gram negative bacteria. They have no action against spores, tubercle bacilli and most of the viruses

58. The common compound are Acetyl trimethyl ammonium bromide ( cetavlon and cetrimide ) The anionic compound , example is common soap , have moderate action, these are more active against gram negative organisms than gram positive . Amphoteric compounds known as Tego compound are active against a wide range of gram positive and gram negative organisms including viruses .

59. Metallic salts Though all salts have some germicidal action depending to their concentration. Salts of silver, mercury, copper are used as disinfectants. They are protein coagulants and have the capacity to combine with free sulphydryl groups of cell enzymes. They shows bacteriostatic actions on topical use.

60. Design and disinfection of operation theater There are so many micro-organisms found in operation theater environment including bacteria, viruses and fungi which can cause significant nosochomial infection. To avoid this it is required to maintain operation theater clean and disinfected at least. Significant risk zone – 700-1800 bacteria carrying particle per cubic meter

61. The operation theater is merely a clean environment but not sterile in which the concentration of airborne particle is controlled and which is constructed and used in a manner to minimize the introduction, generation and retention of particle inside the room and in which other relevant parameters are under control. Example – Temperature, humidity, and pressure are under controlled as necessary.

62. Parameter Desired range- Temperature- 20–23°C Relative humidity- 30–60% Air movement- From clean to less clean areas Air changes - Minimum 15 total air changes per hour

63. Criteria - The operating rooms are set away from hospital by two sets of door. People are required to remove their street cloths and done scrub suits before entering the operation room area. Mask, gowns, gloves and special shoes worn during the operation. The patient and operating site are draped and isolated.

64. The surgical instruments and related instruments should be sterile. After entering the operation theater and before gowning, personnel should take precaution to avoid contamination the open packs of draping material. Once the patient is prepared and draped, only those who are scrubbed, gowned, and gloved may work in surgical site. The back of gowned are considered as unsterile as below waist

65. Chemical agents used as disinfectant in OT Size – 10×10 ft ( 1000 cubic ft) Option 1 - Fogging by using agents like hydrogen peroxide 8–10%, hydrogen peroxide 4–6% with silver nitrate. -Theatre can be used after 20–30 minutes -No irritation, no toxicity issues.

66. Option 2 - Formalin 200 ml + KMnO4 after adequate cleaning and mopping. Close the operation theatre for a period ofat least 8 hours. Then introduce liquor ammonia 200 ml and allow a contact time of minimum 2 hours for neutralization of formaldehyde vapors . Switch on the AC, ideally split AC, for a period of 1 hour. Now the operation theatre is ready for use.

67. Guidelines for hand scrub , gloves, masks, gowns and foot wear. Hand washing guidelines Hand washing removes contamination and decreases the natural bacterial load. It should be done before significant contact with patient or activity likely to cause contamination, such as in intensive care units, while caring for immunocompromised patients. 2. For routine hand wash, neutral soap is adequate. Preferably, liquid soaps in disposable dispensers with dispensing nozzle should be used.

68. 3. Prior to surgical procedures, 4% chlorhexidine or povidone iodine 0.75% is preferred. Manufacturer’s instructions should be referred to. Use a brush to thoroughly scrub up to elbows, followed by rinsing under running water. Wash on all sides of hands and above wrist,vigorously . Nails should be specifically cleaned. Rinse under running water. 4. The hands should be dried using a sterile towel.

69. 5. During procedures wherein multiple handwashes are needed, alcohol-based hand rubs may be used as an adjunct to conventional handwash . 6. Cuts/abrasions should be covered adequately by water-resistant, occlusive dressings, which should be changed if they become wet/soiled

70. Gloves Gloves should be used in all procedures wherein the tissue in contact should be maintained sterile. They are not necessary while adminstering injections. 2. For instrument cleaning, and decontamination procedures, general purpose household gloves are adequate. 3. Gloves should not be washed and reused .

71. 5. They should be changed if they are torn,punctured , or after contact with nonsterile objects. 6. Hands should be washed after removal of gloves

72. Masks, face shields, eye wear These are needed in procedures where splashing, spraying blood/body fluids are expected. Manufacturer’s instructions should be followed. Filter mask (for 0.3 mm particles) should be used for laser plumes.

73. Gowns A disposable or nondisposable gown/apron made of impervious, fluid resistant material should be used where there is a likelihood of contamination or splashes with blood/body fluids

74. Foot wear Enclosed foot wear, disposable/reusable, should be used to protect from injury from sharps or contact with body fluids.

75. Waste management Yellow Plastic Bag Human and animal waste Eg : Tooth, tissue Solid waste Eg : Cotton,plaster and gauze

76. Red Disinfected container/ plastic bag Microbiology and biotechnology waste   Solid waste (disposal items other than sharps and tubing catheters, intravenous sets etc.)

77. Blue/ White translucent Plastic bag/ Puncture proof container Waste sharps Eg : needles, blades .

78. Black Plastic bags Discarded medicines and cytotoxic drugs Eg : outdated drugs and medicines Inceneration ash Chemical waste Liquid waste Eg : cleaning and disinfecting material

79. THANK YOU

80. References Sterilization and disinfection – Annanthnarayan Essentials of microbiology – Chakaraborthy Hospital acquired infections – Purva Mathur Sterilisation and disinfection – Laskins vol1 Narendra patwardhan , Uday Kelkar : Disinfection, Sterilization and Operation theater guidelines for dermatosurgical preactitinor in india ; Indian journal of Dermatology, Venereology 2011 ( Vol 77)