sterilization and disinfection

Sterilization and

Disinfection

SACHIN CHAUHAN – B.SC. NURSING

Sachin [email protected]

In mid 1800s Lister developed

Aseptic techniques to prevent contamination of surgical wounds. Prior to this development:• Nosocomial infections

caused death in 10% of surgeries.

• Up to 25% mothers delivering in hospitals died due to infection.

Sachin Chauhan [email protected]

INTRODUCTION• Microorganisms are the agents of contamination, infection, and decay.

• Hence it becomes necessary to remove them from materials and areas.

• Early civilization practiced salting, smoking, pickling (Preserving) and exposure to sunlight .Sachin Chauhan

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DISINFECTION & STERILIZATION

STERILIZATION Process of

complete destruction of all microbes or micro-organisms & their bacterial endospores / spores on a substance by exposure to physical or chemical agents.

DISINFECTION Process of

reducing or removing microbes or micro-organisms except bacterial endospores but kills vegetative forms of bacteria.


Disinfectant - Chemicals used in disinfection are called disinfectants. Should be applied to inanimate (lifeless) objects.

Decontamination is the process of removal of contaminating pathogenic microorganisms from the articles by a process of sterilization or disinfection.

Antibiotics are substances produced by one microbe that inhibits or kills another microbe.

Sanitization is the process of chemical or mechanical cleansing. It reduces microbes on eating utensils to safe, acceptable levels for public health.

Asepsis is the techniques (such as usage of gloves, air filters, uv rays etc) to achieve microbe-free environment. Antiseptic is the use of chemicals (antiseptics) to make skin or mucus membranes devoid of pathogenic microorganisms. applied to living tissue, Some can be used as both.

Bacteriostatic is a condition where the multiplication of the bacteria is inhibited without killing them.

Bactericidal is that chemical that can kill or inactivate bacteria.Sporicide: An agent that kills spores.

TERMINOLOGY


Types of Disinfection

1) Concurrent Disinfection: Immediate process of removing microorganisms. Eg. Linen contaminated with blood, stool, urine, vomitus etc. 2) Terminal Disinfection:Removal of microorganisms from contaminated objects at convenient time. Eg. Bed, locker, mattress, IV stand, suction & BP apparatus etc. 3) Prophylactic Disinfection:As a preventive measure to prevent the spread of infection. Eg. Boiling of water, pasteurization of milk, hand washing, chlorination of water etc. Sachin Chauhan

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Levels of disinfection• High-level disinfection: can be expected to

destroy all microorganisms, with the exception of large numbers of bacterial spores.

• Intermediate disinfection: inactivates Mycobacterium tuberculosis, vegetative bacteria, most viruses, and most fungi; does not necessarily kill bacterial spores.

• Low-level disinfection: can kill most bacteria, some viruses, and some fungi; cannot be relied on to kill resistant microorganisms such as tubercle bacilli or bacterial spores.


Classification

Category Description Requirement Critical Enters sterile body

cavity Sterile

Semi-critical Contacts mucous membranes, non-intact

skin

High level disinfection

Non-critical Contacts intact skin Low level disinfection


2) Vibration (D) 4) Filtration (D) 5) Cold/Freezing (D) 1) Liquid (D/S) 2) Solid (D) 3) Gas (S)Candle filtersAsbestos filtersSintered glass filter 1) A lcohols 1) Bleaching Powder 1) Ethylen Oxide 10 - 15%

Ionizing (S) Non - Ionizing (D) Membrane filters 2) A ldehydes 2) Formaldehyde1) Electromagnetic 1) Ultra Violet Rays 3) Phenolics2) Cathode 4) Halogens

3) Gamma Rays5) Surface Active Agents & Metalic Salts6) Dyes - Aniline & Acridine7) Blanisol - Pur 1000ml (1 alkyl dimethylbenzyl ammonium chloride - SDI & Instrument Cleanser8) A ldasan 2000 (Surface disinfectants) - Formaldehyde 9.8gm & Glutaral 9.9gm 4) Plasma

5) Betapropiolactone

METHODS OF DISINFECTION / STERILIZATION

3) Radiation

ChemicalPhysical

3) Eco Shield (Hydrogen Peroxide 11% with Diluted Silver nitrate 0.01%) - used for fumigation of OT/ ICU/BB/OPD/Clinic/Lab

Moist Heat1) Burn or Red Heat (D/S)2) Flaming (D)

3) Ironing (D)4) Hot Air Oven (D/S)

1) Below 100o C (Pasteurization @ 60 -72o C) (D)2) At 100o C (Boiling) – 15 to 20 minutes (D)

3) Above 100o C (Steaming) @ low pressure (D)

4) Above 100o C (Steaming) @ low pressure with Formaldehyde (S)

5) Incineration (S)6) Infra Red Conveyer Oven (S)

Dry Heat

Natural (D)

Sun Light

5) Above 100o C (Steaming) @ high pressure (S)

Air 1) Heat/Temperature


Methods of Disinfection/Sterilization

(1) Natural (D)a) Sun Lightb) Air(2) Physical (by temperature)A. Dry Heat

i) Burn or Red Heat (D/S)ii) Flaming (D)iii) Ironing (D)iv) Hot Air Oven (D/S)v) Incineration (S)vi) Infra Red Conveyor Oven (S)



B. Moist Heati) Below 100o C (Pasteurization @ 60 -72o C) (D)ii) At 100o C (Boiling) – 15 to 20 minutes (D)iii) Above 100o C (Steaming) @ low pressure (D)iv) Above 100o C (Steaming) @ low pressure with Formaldehyde (S)v) Above 100o C (Steaming) @ high pressure (S)C) Vibration (D)D) Radiationi) Ionizing (S): Electromagnetic, Cathode & Gamma Raysii) Non – Ionizing (D): UV Rays E) Filtration (D)i) Candle filtersii) Asbestos filtersiii) Sintered glass filteriv) Membrane filters



F) Cold or Freezing (D)

(3) Chemical Method i) Liquid (D/S)• Alcohols – ethyl alcohol & isopropyl alcohol• Aldehydes – Formaldehyde & Glutraldehyde• Phenolics – phenol (Carbolic acid)• Halogens – Iodine, Hypochlorite, Bleaching powder • Acids – Acetic & Boric Acid• Surface Active Agents & Metalic Salts• Dyes - Aniline & Acridine• Blanisol - Pur 1000ml (1 alkyl dimethylbenzyl ammonium

chloride - SDI & Instrument Cleanser• Aldasan 2000 (Surface disinfectants) - Formaldehyde 9.8gm &

Glutaral 9.9gmSachin Chauhan

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ii) Solid (D)• Bleaching Powder

iii) Gas (S)• Ethylen Oxide 10 - 15%• Formaldehyde• Eco Shield (Hydrogen Peroxide 11% with Diluted Silver nitrate

0.01%) - used for fumigation of OT/ICU/BB/OPD/Clinic/Lab• Plasma• Betapropiolactone


Natural Methods


Natural Methods of Disinfection/Sterilization

Sunlight:The microbicidal activity of sunlight is mainly due to the presence of ultra violet rays in it. This method used to disinfect hospital furniture's like Chair, Tables, Locker, Coat, Mattresses. It can be done every 15 days to 2 months by keeping the things for 3 hours at least.

Air:It is an natural disinfectant. It will disinfect the room by keeping them well & cross ventilated. The windows & doors should be kept open for enough light & air.Sachin Chauhan

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Physical Methods


Action of Dry Heat:Dry heat acts by protein denaturation, damage the toxic effects of elevated levels of electrolytes.

Action of Moist Heat:The moist heat acts by coagulation and denaturation of proteins. Moist heat is superior to dry heat in action.

Temperature required to kill microbe by dry heat is more than the moist heat.

Physical Methods of Disinfection/Sterilization


1) Burn or Red heat (D/S): Articles such as bacteriological loops, straight wires,

tips of forceps are sterilized by holding them in Bunsen flame till they become red hot and article like kidney tray, bowl, sputum mug are sterilized by pouring spirit & making fire. This is a simple method for effective sterilization of sucharticles, but is limited to those articles that can be heated to redness in flame.

2) Flaming(D):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.

This method too is limited to those articles that can be exposed to flame. Cracking of the glassware may occur.

Dry Heat


3) Ironing (D): it is an old method and no more in use. By this method we can disinfect the bandages, OT clothes, draping clothes and other linen materials.

Dry Heat


4) Hot air oven (D/S): This method was introduced by Louis

Pasteur. Articles to be sterilized are exposed to high temperature (160o C) for duration of one hour in an electrically heated oven. Since air is poor conductor of heat, even distribution of heat throughout the chamber is achieved by a fan. The heat is transferred to the article by radiation, conduction and convection. The oven should be fitted with a thermostat control, temperature indicator, meshed shelves and must have adequate insulation.

Dry Heat


Sterilisation By Dry Heat:

Hot Air Oven

• Kills by oxidation effects

• The oven utilizes dry heat to sterilize articles

• Operated between 50oC to 250/300oC.

• A holding period of 160oC for 1 hr is desirable.

• There is a thermostat controlling the temperature.

• Double walled insulation keeps the heat in and conserves energy,

Dry Heat


5) Incineration (S): This is a method of destroying

contaminated material by burning them in incinerator. Articles such as soiled dressings; animal bodies, 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. Burning of polystyrene materials emits dense smoke, and hence they should not be incinerated.

Dry Heat


5) Infra Red Conveyor Oven (S): Similar to other electrical conveyor ovens, the infra red conveyor oven utilizes short wave infra red lamp element to achieve maximum heat.

Specification :-• It is similar to Electrical belt Conveyor Oven but it

has infrared heating elements instead of other heating media.

• Temperature control: Automatic-Electronic • Increases Production.• Better quality of Product.• Less process time.• Less electric consumption as compared to• other convection belt conveyor ovens

Dry Heat


Infra Red Conveyor Oven


1) Pasteurization (D):

Process of killing of pathogens in the milk but does not sterilize it .

Milk is heated at 63oC for 30 mins. (HOLDER METHOD)

At 72oC for 15-20 Sec. Rapid cooling to 13oC(FLASH PROCESS)

Moist HeatBelow 100o C


2) Hot Water Bath (D):• To inactivate non sporing bacteria for the

preparation of vaccines - Special vaccine bath at 60oC for one hour is used

• Serum or body fluids containing coagulable proteins can be sterilized by heating for 1 hr at 56oC in a water bath for several successive days.



Water BathSachin Chauhan

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3) Inspissator (D):Sterilizes by heating at 80-85oC for half an hour for 3 successive days

Used to sterilize media such as Lowenstein-Jensen & Loefller’s serum



Inspissator


2) Boiling(D):

Kills vegetative forms of bacterial pathogens.

Hepatitis virus: Can survive up to 30 minutes of boiling.

Endospores: Can survive up to 20 hours or more of boiling

Moist HeatAt 100o C


3) Steaming at Low Atmospheric Pressure (D):Steam is generated using a steamer (Koch/ Arnold)Consists of a Tin cabinet Has a conical lid to enable the drainage of condensed steam Perforated tray above ensures materials are surrounded by steam.For routine sterilization exposure of 90 mins is used.

4) Steaming at Low Pressure with Formaldehyde (S):Instruments like scopes, plastic & anesthetic equipment's should be sterilized by steaming at low pressure with formaldehyde.

The drawback of this method is the cycle time is about 2 hours at 80oC & it irritates the living tissues, if formaldehyde remains in an articles.

Moist HeatAbove 100o C


Steaming at Low or Atmospheric PressureSachin Chauhan

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5) Steaming at High Pressure - Autoclave (S):Works on the principle of Steam under pressure

Invented by Charles Chamberland in 1879.

Autoclave machine is made up of metal body & consists of a vertical or a horizontal cylinder.One end has an opening which is meant for keeping materials to be sterilised.The lid is provided with a Pressure gauge, to measure the pressureA safety valve is present to permit the escape of steam from the chamberArticles to be sterilised are placed in the basket provided.Sterilisation is carried out under pressure at 121º for 15 mnts.

Moist HeatAbove 100o C


Steaming at High Pressure - AutoclaveSachin Chauhan [email protected]

ULTRASONIC AND SONIC VIBRATION

Bactericidal

Microorganisms vary in their sensitivity, hence no practical value in sterilisation and disinfection.

Vibration (D)


1) Non – Ionizing (D):

Absorbed as heat

Can be considered as hot air sterilisation

Used in rapid mass sterilisation of pre packed Syringes and catheters

Eg: UV rays & Infrared Rays

Radiation


ICU – ISOLATION ROOM SINGLE CLOSED CUBICLE

CASES – OPEN TB , ANTHRAX, MRSA etc…

UV LIGHT FOR DISINFECTION


2) Ionizing (S):

Electromagnetic, Cathode, X- rays, gamma rays & cosmic rays.

High penetrative power

No appreciable increase in the temperature – COLD STERILISATION

Sterilise plastics Syringes, catheters, grease fabrics metal foils

Radiation


Filtration helps to remove bacteria from heat labile liquids such as sera and solutions of sugar, Antibiotics. The following filters are used1. Candle filters2. Asbestos filters3. Sintered glass filter4. Membrane filters

Filtration (D)


CANDLE FILTERS• Widely used for purification of

waterTwo types(a) Unglazed ceramic filter – Chamberland filter

(b) Diatomaceous earth filters – Berkefeld filter


CANDLE FILTERSachin Chauhan [email protected]

ASBESTOS FILTER• Disposable single use discs

• High adsorbing tendency

• Carcinogenic Eg: Seitz filter


SEITZ FILTER

ASBESTOS DISCSSachin Chauhan [email protected]

SINTERED GLASS FILTER

• Prepared by heat fusing powdered glass particles of graded size

• Cleaned easily, brittle, expensive.


SINTERED GLASS FILTERSachin Chauhan [email protected]

MEMBRANE FILTERS• Made of cellulose esters or other

polymers

Uses • Water purification & analysis• Sterilization & sterility testing • Preparation of solutions for

parenteral useSachin Chauhan

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MEMBRANE FILTER


http://www.rickly.com/sai/images/MEMBRANE.JPG

In this method temperature should be kept at -4OC which stops the growth of micro-organism but this process will not able to kill them. For eg. Refrigerators

Cold/Freezing (D)


Chemical Methods


Chemical Methods of Disinfection/Sterilization

1) Liquid2) Gas3) Solid


Specific Chemical Antimicrobial Agents

• Halogens: Hypochlorous acid Chlorine (Cl),Iodine (I), Bromine (Br), Chloramine

• Alcohols: denature proteins, skin antiseptics• Phenols: disrupt cell membranes• Oxidizing Agents:H2O2 disenfectant• Alkylating Agents: disrupt nucleic acids and

protein structures, may cause cancer, formaldehyde, ethylene oxide, glutaraldehyde

• Dyes: acridine and methylene blue, crystal violet

• Other Agents: plant oils for thyme and clove, nitrates, sulfites, sodium nitrate ( p 338)


Chemical Methods(Liquid)


Chemical agents act by

• Protein coagulation• Disruption of the cell membrane• Removal of Sulphydryl groups• Substrate competition


1) ALCOHOLS• Ethanol /Isopropyl alcohol are

frequently used• No action on spores• Concentration recommended 60-90%

in waterUses• Disinfection of clinical thermometer.• Disinfection of the skin –

Venupuncture Sachin Chauhan

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2) ALDEHYDES• Formaldehyde & Glutaraldehyde

are frequently used• Formaldehyde is bactericidal,

sporicidal & has a lethal effect on viruses.

• Glutaraldehyde is effective against Tubercle bacilli, fungi and viruses


USESFORMALDEHYDE• To preserve anatomical specimens • Destroying Anthrax spores in hair and wool• 10% Formalin+0.5% Sodium tetra borate

is used to sterilise metal instruments

GLUTARALDEHYDE• Used to treat corrugated rubber

anesthetic tubes, Face masks, Plastic endotracheal tubes, Metal instruments and polythene tubing Sachin Chauhan

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2% GLUTARLDEHYDE

Sterilization

Disinfection

8-10 Hrs used for :- Pneumatic circuits. i.e.- ventilator tubing O2 masks ventury devices nebulizer chamber

15-30 Mts used for dis infecting endoscopes Respiratory tubing's


PHENOLS• Obtained by distillation of coal tar• Phenols are powerful microbicidal

substances• Phenolic derivatives have been

widely used as disinfectants for various purposes in hospitals

• Eg: Lysol, cresol


USES

• Various combinations are used in the control of pyogenic cocci in surgical & neonatal units in hospitals.

• Aqueous solutions are used in treatment of wounds


LINEN

SOAKED IN 7% LYSOL


SUCTION TRAYSo TO BE CHANGED EVERYDAY

o SUCTION CUPS -CHANGED AFTER EACH USE - IMMERSED IN 7% LYSOL FOR 1Hr - WASHED WITH SOAP &WATER - SENT FOR AUTOCLAVING


HALOGENS• Iodine in aqueous and alcoholic

solution has been used widely as a skin disinfectant

• Actively bactericidal with moderate against spores

• Chlorine and its compounds have been used as disinfectants in water supplies & swimming pools


SURFACE ACTIVE AGENTS AND METALLIC SALTS

Substances which reduce the surface tension – Surface active agents

• Cations are widely used in the form of quaternary ammonium compounds.

• Markedly bactericidal, active against Gram positive organisms.

• No action on spores, tubercle bacilli, viruses


METALLIC SALTS

• The salts of silver, copper and mercury are used as disinfectants.

• Act by coagulating proteins

• Marked bacteriostatic, weak bactericidal and limited fungicidal activity


Blanisol – Pur 1000ml (Surface Disinfectants)

Blanisol - Pur 1000ml (1 alkyl dimethylbenzyl ammonium

chloride - SDI & Instrument Cleanser


Blanisol – Pur 1000ml (Surface Disinfectants)


Aldasan 2000 (Surface Disinfectants)

Aldasan 2000 (Surface disinfectants) – Formaldehyde

9.8gm & Glutaral 9.9gm


Aldasan 2000 (Surface Disinfectants)


Sterilium (80% Ethanol) (Hand Disinfectants)

• The classic among rub-in hand disinfectants for hygienic and surgical hand disinfection

• best peer-reviewed hand-disinfectant – quality since 1965

• possesses an excellent immediate effect• provides very good residual effect• excellent skin tolerability even with long-term use• Areas of application

For hygienic and surgical rub-in hand disinfection – independent of washbasin and water. For all areas that are relevant to hygiene.


Sterilium (Hand Disinfectants)


DYES

Two groups of dyes are used

Aniline dyes

Acridine dyes


ANILINE DYES

• Are Brilliant green, Malachite green & Crystal violet

• Active against Gram positive bacteria

• No activity against tubercle bacilliSachin Chauhan

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ACRIDINE DYES

• Acridine dyes in use are orange in colour

• Effective against Gram positive than Gram negative

• Important dyes are Proflavine, Acriflavine,Euflavine


Chemical Methods(Gases)


GASES

Ethylene Oxide–Colourless ,Highly penetrating gas with a sweet ethereal smell.

–Effective against all types of microorganisms including viruses and spores


ETHYLENE OXIDE(EO)Used for polythene and plastic itemsE.g.:- Ambu bag, Baines circuit, Domes, Biopsy Needle, Electric items, Rubber items Pre-caution:-Thorough cleanliness and drynessAdequate aeration at least 12Hrs


USES• Specially used for sterilising heart-

lung machines,respirators,sutures,dental equipments, books and clothing.

• Also used to sterilise Glass, metal and paper surfaces ,plastics, oil,some foods and tobacco.


FORMALDEHYDE GAS

• Widely employed for fumigation of operation theatres and other rooms


Eco Shield

Eco Shield (Hydrogen Peroxide 11% with

Diluted Silver nitrate 0.01%) - used for

fumigation of OT/ICU/BB/OPD/Clinic/Lab


BETA PROPIOLACTONE• Used in fumigation

• For sterilisation 0.2% BPL is used

• Has a rapid biocidal activity

• Very effective against virusesSachin Chauhan

[email protected]

Plasma Sterilizer


The level of disinfection achieved depends on several factors:

• Contact Time & Temperature• Items must be thoroughly cleaned before

processing, because organic material (e.g., blood and proteins) may contain high concentrations of microorganisms. Also, such organic material may inactivate chemical germicides and protect microorganisms from the disinfection or sterilization process.

• Some disinfectants gradually loss their effectiveness after diluting with water.

• Use of same solution for long time, loses their effectiveness. Also it is prone to grow micro-organisms.

• This method is only used for non boilable, scopes & sharp instruments.

POINTS TO REMEMBER FOR CHEMICAL DISINFECTION


Thank you…


Actions

Spirit:• General skin disinfectant constricts your skin,

preventing dirt and stain from infecting the skin. • Also can be used as a rub to harden the skin of the

hands and feet.• It prevents bleeding while giving injection due to

constriction of blood vessels.


sterilization and disinfection

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