STERILIZATION AND ASEPSIS

1. STERILIZATION AND ASEPSIS

2. INTRODUCTION: Sterilization is defined as the process by which an article, surface or medium is freed of all living micro-organisms either in the vegetative or spore state. Disinfection means the destruction or removal of all pathogenic organisms or organisms capable of giving rise to infection Anti-sepsis is used to indicate the prevention of infection usually by inhibiting the growth of bacteria in wounds or tissues

3. HISTORY OF ASEPSIS Hippocrates – cleanliness Semmelweis (1847) – washing hands prior to delivery reduced puerperal fever Lister (1865) – influenced by louis pasteur suggested carbolic acid as an antiseptic Lawson tait – antisepsis to asepsis, introduced principles and practices of asepsis Ernst von Bergmann (1880) – introduced autoclave

4. CLASSIFICATION • PHYSICAL AGENTS: 1) SUNLIGHT 2) DRYING 3) DRY HEAT a) FLAMING b) INCINRATION c) HOT AIR 4) MOIST HEAT: PASTEURISATION,BOILING,STEAM UNDER NORMAL PRESSURE, STEAM UNDER PRESSURE. 5) FILTRATION: CANDLES, ASBESTOS PACKS, MEMBRANES. 6) RADIATION 7) ULTRASONIC AND SONIC VIBRATIONS. • CHEMICAL AGENTS: 1) ALCOHOLS- ETHLY ISOPROPYL,TRICHLOROBUTANOL 2) ALDEHYDES- FORMALDEHYDE, GLUTARALDEHYDE. 3) DYES- 4)HALOGENS ` 5) PHENOLS 6) SURFACE ACTIVE AGENTS 7) METTALIC SALTS 8) GASES- ETHYLENE OXIDE, FORMALDEHYDE, BET PROPIOLACTONE

5. PROPERTIES An ideal antiseptic or disinfectant should: • Have a wide spectrum of activity and be effective against all micro organisms • Be active in the presence of organic matter • Be effective in acid as well as alkaline media • Have speedy action • have high penetrating power • Be stable • Be compatible with other antiseptics and disinfectants • Not corrode metals • Not cause local irritation or sensitization • Not interfere with healing • Not to be toxic if absorbed into circulation • To be cheap and easily available • Be safe and easy to use

6. FACTORS THAT DETERMINE THE POTENCY OF DISINFECTANTS • Concentration of the substance • Time of action • pH of the medium • Temperature • Nature of the organism • Presence of extraneous material

7. MODES OF ACTION • Protein coagulation • Disruption of cell membrane • Removal of the free sulphydryl groups • Substrate competition

8. 4 Stages :- • Pre-sterilization cleaning. • Packaging. • Sterilization methods. • Aseptic storage.

9. Physical AgentsSUNLIGHT • Bactericidal activity • Under natural conditions Action: primarily- UV rays DRYING • 4/5th by wt bacterial cell-water • Drying-deleterious effect on bacteria • Unreliable & theoretical interest • spores are not effected

10. HEAT • Most reliable method • Factors influencing: a. Nature of heat b. Temperature & time c. Number of microorganisms present d. Characteristic of organisms e. Type of material

11. DRY HEAT Action- • Protein denaturation • Oxidative damage • Toxic effect of elevated levels of Electrolytes 1.Flaming: Inoculating loops or wires, points of forceps, searing spatulas under Bunsen flame-till red hot

12. 2. Incineration: Destruction of materials – • Soiled dressings • Animal carcasses • Bedding • Pathological materials • Plastics-PVC, polythene • Except polystyrene.

13. 3. Hot Air Oven: • Pastuer-1876 Holding period-160c-1hr • Sterilizes-glassware, forceps, scissors, scalpels, all-glass syringes, swabs, liquid paraffin,powders • Control: Clostridium tetani

14. MOIST HEATMechanism of action:- Dry saturated steam Meets cooler surface Gets condensed into a packet of water Latent heat lib. . Denaturation enzyme. -1600ml steam at 100° C . Membrane damage. At atmospheric pressure condenses . Chromosomal damage. to 1ml H2O 518 cal heat. . Enzyme coagulation.

15. Types of moist heat- Below 100°C. (Pasteurization) At 100°C . ( Tyndallisation ) Above 100°C . ( Under pressure )

16. Below 100 °C ( Pasteurization) 2 Types- Holder method :63°C for 30 mins. Flash process :72°C for 20 sec…rapid cooling to 13°C. Mycobacteria, brucellae & salmonellae……... Application:- - OT table side or bed side sterilization. - Vaccines of non-sporulating bacteria. - Sterilization of L-J media & Loeffler’s serum.

17. Tyndallisation • Principle- 90-100°C for 20 min on three successive days Followed by incubation at 37°C in between. • At 100°C:- • Boiling…Vegetative bacteria killed immediately..sporing bacteria…not a recommended procedure…as a disinfection.. • Used in cases where boiling is considered adequate..closed lid….10-30 min.

18. MOIST HEAT • Temperature <100c • Pasteurization of milk: holder method -63c-1/2hr flash method -72c-15-20 sec Cooling quickly -13c or lower

19. Temperature at 100c: Boiling: • vegetative bacteria-90-100c • hard water-not to be used • 2%NaHCO3-increases boiling point of water. Steam at atmospheric pressure:100c * Koch or Arnold steamer used * one exposure of 90min * Tyndallization/intermittent sterilization * Media containing sugars or gelatin- 100c for 20 min-3 days

20. AUTOCLAVE STEAM UNDER PRESSURE: * Principle: water boils when its vapour pressure equals that of the surrounding atmosphere. * saturated steam has penetrative power. when steam comes in to contact with a cooler surface it condenses to water and gives up its latent heat to that surface . *The larger reduction in volume sucks in more steam to the area and the process continues till the temperature of that surface is raised to that of the steam. The condensed water ensures moist conditions for killing the microbes present. 121°C (250°F)..15-20 min..15 lbs. Dressings , instruments, laboratory ware, media and pharmaceutical products can be sterilized. .

21. Several types of steam sterilizers are in use: • Laboratory autoclaves • Hospital dressing sterilizers • Bowland instrument steilizers, and • Rapid cooling sterlizers (even the domestic pressure can be used as a sterilizer).

22. Consideration during Autoclaving 1. Ensure complete air removal for temp to reach 121°C. 2. Ensure loose packing in the chamber. 3. Always remove chemicals and then place. 4. Tightly sealed materials may become dangerously pressurized causing injury when removed. 5. A routine autoclave maintenance program recommended.

23. STERILISATION CONTROL * For determining the efficacy of moist heat sterilisation , spores of bacillus stearothermophilus are used as the test organism. Chemical indicators, autoclave tapes and thermocouples may also be used instead.

24. Glass bead sterilizer Glass beads, molten metal and salt. Temp- 220°C, 10 sec. Use- endodontic files, burs.. Disadv:- no uniform heat.

25. FILTRATION To remove bacteria from heat labile liquids -sera, sugar solutions & antibiotics. Types: a. candle filters: i. unglazed ceramic filters ii. Diatomaceous earth filters b. Asbestos filters: c. Sintered glass filters d. Membrane filters

26. RADIATION Types: a. Non ionising : Infrared radiation- prepacked syringes & catheters UV radiation-entry ways, OT & lab b. Ionsing radiation {cold sterilization} : X-rays, gamma rays & cosmic rays high penetrating power-lethal to DNA sterilizes- plastics, syringes, swabs, catheters,

27. CHEMICAL AGENTS Alcohols: a) Ethyl alcohol (ethanol) and isopropyl alcohol are the most frequently used. mainly used as skin antiseptics and act by denaturing the bacterial proteins. (but no actions on spores and viruses). b) Methyl alcohol is effective against fungal spores and is used for treating cabinets and incubators affected by them.

28. ALDEHYDES: a) Formaldehyde in aqueous solutions, markedly bactericidal and sporicidal- has a lethal effect on viruses. 10% formalin with ½ % sodium tetraborate is used to sterilise clean metal instruments. Formaldehyde gas is used for sterilising instruments and heat sensitive catheters, also for fumigating wards, sick rooms and labs b) Glutaraldehyde is specially effective against tubercle bacilli, fungi and viruses ( less toxic n irritant to the eyes and the skin than formaldehyde.) Corrugated rubber anaesthetic tubes and face masks, plastic endotracheal tubes, metal instruments and polythene tubing.

29. Dyes: a) Aniline dyes and b) Acridines are used extensively as skin and wound antiseptics (bacteriostatics in high dilution but of low bactericidal activity).. They are more active against gram positive than gram negative organisms. They have no activity against tubercle bacilli. Lethal effects on bacteria are due to their reactions with the acid groups in the cell.

30. Halogens: 1) Iodine in aqueous and alcoholic solutions has been used as a SKIN DISINFECTANT. Is an active bactericidal agent with a moderate activity against spores, tubercle bacillus and number of viruses. Compunds of iodine ( iodophores) are more active than aqueous or alcoholic soln. 2) Chlorine and hypochlorites are markedly bactericidal. They have a wide spectrum of activity against viruses. * The organic chloramines are used as antiseptics for dressing wounds.

31. PHENOLS: Lister( father of antiseptic surgery) first introduced their use in surgery. The lethal effect phenols is due to their capacity to cause cell membrane damage, releasing cell contents and causing lysis. phenols and their derivatives are widely used for various purposes in hospitals & the combinations( chlorophenols and chloroxyphenols) are used in the control of pyogenic cocci in surgical and neonatal units.

32. GASES: Ethylene oxide: its action is due to its power of alkylating the amino, carboxyl, hydroxyl and sulphydryl groups in the protein molecule and also reacts with the DNA and RNA. Effective against all types of microorganisms including viruses and spores. Specially used for sterilizing heart-lung machines, respirators, sutures, dental equipments and clothing. Formaldehyde gas: widely employed for fumigation of operation theaters and other rooms. BetaPropiolactone(BPL): (condensation product of ketane and formaldehyde) More effective than formaldehyde for fumigating purposes. It has a rapid biocidal action but unfortunately has carcinogenic activity. It is capable of killing all micro organisms and is very active against viruses.

33. Surface acing agents: a)anionic, b)cationic, c)nonionic, d)amphoteric The most important antibacterial agents are the cationic surface active agents. These act on the phosphate groups of the cell membrane and also enter the cell. Metallic salts: salts of silver, copper, and mercury are used as disinfectants. Protein coagulants and have the capactiy combine with free sulphydyrl groups of cell enzymes. The organic compounds, thio mersal, phenyl mercury nitrate and mercurochrome are less toxic and are used as mild antiseptics and marked bacteriostatics, limited fungicidal and weak bactericidal activity.

35. UNIVERSAL PRECAUTIONS • CONCEPT: To address the inability of health care providers to specifically identify all patients with communicable diseases. THEORY: protection of self , staff and patients from contamination by using barrier techniques when treating all patients as if they all had a communicable disease ensures that everyone is protected from those who do have an infectious process. COMPONENTS: • All doctors and staff who come in contact with patients blood or secrtetions , whether directly or in aerosol form , wear barrier devices including face mask eye protection and gloves • decontaminating or disposing of all surfaces that are exposed to patient blood tissues and secretions . • avoidance of touching and thereby contaminating surfaces ( eg: dental record , telephone, etc.,) with contaminated gloves or instruments.

36. PERSONAL BARRIER PROTECTION GLOVES: • All clinical personnel must wear treatment gloves during all treatment procedures. • After each appointment , or if leak is detected , remove gloves, wash hands and put on fresh gloves. • Instead of attempting to wash gloved hands before opening drawers or handling items adjacent to the operatory, use tongs , a paper towel, or a food handler’s over glove, to prevent contamination. • All personnel with weeping or draining lesions that could infect patients abstain from patient contact.

37. Gloves that become penetrated or torn can imbibe patient fluids and therefore should be removed. • Viruses have been found to penetrate not more than one intact latex gloves out of hundred. Double gloving prevents perforations of the inner glove and therefore, adds protection. • Latex gloves must have less than four percent leak detectable water test. While handling sharp instrument wear puncture resistant utility gloves. • Nitrile latex gloves can be washed inside and out, disinfected or steam autoclaved

39. PROTECTIVE MASKS AND HAIR PROTECTION. • wear masks to protect against heavy spatter ,blood droplets. Change the mask between every patient or whenever it becomes visibly soiled or moist. • masks with highest filtration are rectangular, folded types used for surgeries. • hair can trap heavy contamination hence should be kept out of the treatment field by a protective head cap.

40. PROTECTIVE OVER GARMENTS • for protection of clothing and skin , sleeves with knit cuffs that tuck under gloves are preffered. • Wearing contaminated garments home or out of the clinical area should not occur. • hot water up to 70 c or cool water containing 50 to 150ppm of chlorine provided by liquid laundry bleach would provide more antimicrobial action. Use of a hot air dryer and /or ironing is also beneficial

41. SCRUB PROCEDURE • The recommended scrub procedure for a particular operating room is usually posted in the scrub area. The initial scrub usually encompasses the following routine. • rinse hands and forearms with water, then wash with soap. • cleanse nails with an orange wood stick or nail cleanser contained in scrub packs. • Start 10 minute scrub and work to an abundant lather, using either brush or sponge. The palms, backs of hands, and fingers are scrubbed first then the forearms. Scrub one hand and arm and then the other. • when rinsing, raise both hands so that water will run down and off at the elbows. • When the 10 minute scrub is finished , raise hands and prepare to enter operating room.

44. STERILE TECHNIQUE: • when the scrubbing is completed, keep the arms and hands raised. • when the gown and gloves are on, do not drop hands below waist level or raise above the head. • Remember the back of the operating gown is not sterile. Do not reach behind anyone. • When passing another gowned person, pass back to back. • when standing at the table, keep hands on sterile drape that covers the patient (do not exert pressure because this may interfere with respiration). • Do not touch mask or cap. If adjustment is necessary, ask the circulating nurse. • Do not break the scrub ( take off gloves, etc.) until surgery has been completed.

45. PREPARATION FOR INTRAORAL PROCEDURES • Make sure that all anesthetic equipment is cleared from the operative site. • Prepare the peri-oral regions first starting at the corner of the mouth and working outward to the cheek , once at the periphery, do not return to the starting point. • With a freshly dampened sponge, repeat this process on the other side of the face. • the inside of the mouth may be cleansed. Although the mouth is not a sterile area and cannot be sterilized, some surgeons prefer at least to sponge out the mouth prior to surgery 5. When the preparatory procedure is completed, the circulating nurse will take the cup and sponge stick

46. DRAPING THE PATIENT • after the preparation is completed, the patient is draped. • the simplest method of draping is the “ four towel and thyroid drape” . Where thyroid drapes are not available, a large body sheet may be used in conjunction with a cystoscopy drape. • In the technique , the towels are applied first then the body sheet, and finally the cysto sheet. • In both techniques , the only visible area left is the operative site

49. HBV RISKS FOR CLINICAL PERSONNEL DATA RELATED: 1. Rate of cross infection is found to be 30%. 2. HBV is found in 1 of 100 to 500 persons in general population. • Even only 1000³ virions per ml of blood of HBV is capable of transmitting the disease • HBV is found to be resistant to dessication and chemical disinfectants like alcohols , phenol, etc., • Up to 90% of HIV infected patients have been infected with HBV Whether infected persons are symptomatic or not , they can transmit HBV infection . 6.. Mortality rates from HBV infection is 6.6 times to that of HIV. 7. HBV is found in small concentrations in saliva and can be transmitted by contamination of broken skin , mouth, or eyes with blood contaminated saliva.

50. HIV RISK FOR CLINICAL PERSONNEL DOCUMENTED DATA RELATED TO HIV : Rate of cross infection is 0.3% . • unlike HBV , very low levels of HIV are found in blood of infected patients. 2. in dried , infected blood 99% of HIV is found inactivated in approx 90 minutes. But in wet conditions virus may survive for two or more days. 3. HIV is killed by all methods of sterilization in less than 2 minutes ( exception quarternary ammonium compounds) • HIV can be transmitted by heavily splattered or splashed blood contaminated fluids, but aerosols are not found to transmit HBV or HIV . • Barrier techniques have great successful rates in decreasing incidence of HIV infection.