sterilization and disinfection

STERILIZATION STERILIZATION AND DISINFECTIONAND DISINFECTION

Dr. Ashish JawarkarDr. Ashish JawarkarM.D.M.D.

Parul Sevashram HospitalParul Sevashram Hospital

INTRODUCTIONINTRODUCTION

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

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

Early civilization practiced salting, Early civilization practiced salting, smoking, pickling and exposure to smoking, pickling and exposure to sunlight .sunlight .

In mid 1800s Lister developed In mid 1800s Lister developed Aseptic techniquesAseptic techniques to prevent to prevent

contamination of surgical wounds. Prior contamination of surgical wounds. Prior to this development:to this development:• Nosocomial infections caused death in Nosocomial infections caused death in

10% of surgeries.10% of surgeries.• Up to 25% mothers delivering in Up to 25% mothers delivering in

hospitals died due to infection. hospitals died due to infection.

DEFINITIONDEFINITION

STERILIZATIONSTERILIZATION

The process of freeing an article from The process of freeing an article from microorganisms including their spores.microorganisms including their spores.

DISINFECTION:DISINFECTION: Reducing the number of pathogenic microorganisms to the point where they no longer cause diseases.

SepsisSepsis: : Comes from Greek for decay or Comes from Greek for decay or putrid. Indicates bacterial contamination.putrid. Indicates bacterial contamination.

AsepsisAsepsis: Absence of significant : Absence of significant contamination.contamination.

Aseptic techniquesAseptic techniques are used to prevent are used to prevent contamination of surgical instruments, contamination of surgical instruments, medical personnel, and the patient during medical personnel, and the patient during surgery. surgery.

Aseptic techniques are also used to Aseptic techniques are also used to prevent bacterial contamination in food prevent bacterial contamination in food industry.industry.

Bacteriostatic Agent: Bacteriostatic Agent:

An agent that An agent that inhibitsinhibits the growth of the growth of bacteria, but does not necessarily kill bacteria, but does not necessarily kill them. them.

BactericideBactericide: : An agent that kills bacteria. Most do not kill An agent that kills bacteria. Most do not kill

Endospores.Endospores.

SporicideSporicide:: An agent that kills spores.An agent that kills spores.

Methods of SterilisationMethods of Sterilisation

Microbial ControlMicrobial Control MethodsMethods

Physical Agents Chemical Agents Mechanical Removal Methods

Physical AgentsPhysical Agents

Heat Radiation

Dry Moist

Incineration

Dry Oven

Steam Under Pressure

Boiling Water/Hot Water Pasteurization

Sterilization

Ionizing Non Ionizing

X Ray, Cathode, Gamma

Disinfection

UV

Sterilization Disinfection

Chemical AgentChemical Agent

Gas Liquids

SterilizationDisinfectionAnimate Inanimate

ChemotherapyAntisepticsSterilizationDisinfection

Mechanical Removal Mechanical Removal MethodsMethods

Filtration

Air Liquids

Disinfection Sterilization

Physical Methods of SterilisationPhysical Methods of Sterilisation

Sterilisation By 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,

Uses:Uses:

To sterilise Forceps, Scissors, Scalpels, Swabs.To sterilise Forceps, Scissors, Scalpels, Swabs.

Pharmaceuticals products like Liquid paraffin, Pharmaceuticals products like Liquid paraffin, dusting powder, fats and grease.dusting powder, fats and grease.

FLAMINGFLAMING

Inoculation loop Inoculation loop or Wire, the tip of or Wire, the tip of Forceps and Forceps and spatulas are held spatulas are held in a bunsen flame in a bunsen flame till they are red till they are red hothot..

Flaming Flaming

INCINERATIONINCINERATION

This is an excellent method of This is an excellent method of destroying materials such as destroying materials such as contaminated cloth, animal contaminated cloth, animal carcasses and pathological carcasses and pathological materials.materials.

IncinerationIncineration

Dry heat - HOT AIR OVENDry heat - HOT AIR OVEN Holding temp & time: 160Holding temp & time: 16000C for 1 hrC for 1 hr Used for glassware, forceps, swabs, water Used for glassware, forceps, swabs, water

impermeable oils, waxes & powdersimpermeable oils, waxes & powders Before placing in hot air oven Before placing in hot air oven

Dry glassware completelyDry glassware completely Plug test tubes with cotton woolPlug test tubes with cotton wool Wrap glassware in Kraft papersWrap glassware in Kraft papers

Don’t over load the ovenDon’t over load the oven Allow free circulation of air between the material Allow free circulation of air between the material

Dry heat - HOT AIR OVENDry heat - HOT AIR OVEN Sterilization controls: to check whether the Sterilization controls: to check whether the

equipment is working properlyequipment is working properly Chemical controls: Browne’s tubesChemical controls: Browne’s tubes

Color change from red to greenColor change from red to green ThermocouplesThermocouples Biological controls: paper strips containing10Biological controls: paper strips containing1066 spores spores

of Clostridium tetaniof Clostridium tetani Place strips in oven along with other material for the Place strips in oven along with other material for the

sterilization sterilization Later culture the strips in thioglycollate broth or RCM at 37Later culture the strips in thioglycollate broth or RCM at 3700C C

for 5 daysfor 5 days Growth in medium indicates failure of sterilizationGrowth in medium indicates failure of sterilization

Dry heat – Hot air ovenDry heat – Hot air oven

MOIST HEAT STERILIZATIONMOIST HEAT STERILIZATION

Kills microorganisms byKills microorganisms by coagulatingcoagulating their their proteins. proteins.

MOIST HEAT STERILISATION IS CARRIED OUT MOIST HEAT STERILISATION IS CARRIED OUT WITH FOLLOWING METHODSWITH FOLLOWING METHODS

Temp below 100Temp below 100ooC: C: “Pasteurisation”, Inspissator.“Pasteurisation”, Inspissator.

Temperature at 100Temperature at 100ooC: C: Boiling.Boiling.

Steam at atmospheric pressure: Steam at atmospheric pressure: Koch/Arnold’s Koch/Arnold’s steamer.steamer.

Steam under pressure: Steam under pressure: Autoclave.Autoclave.

PasteurisationPasteurisation Process of killing of pathogens in the milk but Process of killing of pathogens in the milk but

does not sterilize it .does not sterilize it .

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

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

Water BathWater Bath

HOT WATER BATHHOT WATER BATHTo inactivate non sporing bacteria for the To inactivate non sporing bacteria for the

preparation of vaccines - preparation of vaccines - Special vaccineSpecial vaccine bathbath at 60 at 60ooCC for one hour is usedfor one hour is used

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

Inspissator

INSPISSATORINSPISSATORSterilizes by heating at 80-85Sterilizes by heating at 80-85ooC for half an C for half an

hour for 3 successive dayshour for 3 successive days

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

TEMPERATURE AT 100TEMPERATURE AT 100OOCCBoiling:Boiling: Kills vegetative forms of bacterial Kills vegetative forms of bacterial

pathogens. pathogens. Hepatitis virusHepatitis virus: Can survive up to 30 : Can survive up to 30

minutes of boiling.minutes of boiling. EndosporesEndospores: Can survive up to 20 hours or : Can survive up to 20 hours or

more of boilingmore of boiling

Steam Sterilizer

STEAM AT ATMOSPHERIC PRESSURESTEAM AT ATMOSPHERIC PRESSURE

Steam is generated using a steamer Steam is generated using a steamer (Koch/ Arnold)(Koch/ Arnold)

Consists of a Tin cabinet Consists of a Tin cabinet Has a conical lid to enable the drainage of Has a conical lid to enable the drainage of

condensed steamcondensed steamPerforated tray above ensures materials Perforated tray above ensures materials

are surrounded by steam.are surrounded by steam.For routine sterilization exposure of 90 For routine sterilization exposure of 90

mins is usedmins is used

For media containing sugar and gelatin For media containing sugar and gelatin exposure of 100exposure of 100ooC for 20 min for 3 C for 20 min for 3 successive days is usedsuccessive days is used

The process is termed as The process is termed as Tyndallisation /Intermittent SterilizationTyndallisation /Intermittent Sterilization

STEAM UNDER PRESSURE - STEAM UNDER PRESSURE - AUTOCLAVEAUTOCLAVE

Works on the principle of Works on the principle of Steam under Steam under pressurepressure

Invented by Charles Chamberland in 1879. Invented by Charles Chamberland in 1879.

AUTOCLAVE

Autoclave consists of a vertical or a Autoclave consists of a vertical or a horizontal cylinder.horizontal cylinder.

One end has an opening which is meant One end has an opening which is meant for keeping materials to be sterilised.for keeping materials to be sterilised.

The lid is provided with a Pressure gauge, The lid is provided with a Pressure gauge, to measure the pressureto measure the pressure

A safety valve is present to permit the A safety valve is present to permit the escape of steam from the chamberescape of steam from the chamber

Articles to be sterilised are placed in the Articles to be sterilised are placed in the basket providedbasket provided

Sterilisation is carried out under pressure Sterilisation is carried out under pressure at 121at 121ºº for 15 mnts. for 15 mnts.

CHEMICAL AGENTSCHEMICAL AGENTS

Chemical agents act byChemical agents act by Protein coagulationProtein coagulationDisruption of the cell membraneDisruption of the cell membraneRemoval of Sulphydryl groupsRemoval of Sulphydryl groupsSubstrate competitionSubstrate competition

ALCOHOLSALCOHOLSEthanol /Isopropyl alcohol are frequently Ethanol /Isopropyl alcohol are frequently

usedusedNo action on sporesNo action on sporesConcentration recommended 60-90% in Concentration recommended 60-90% in

waterwaterUsesUsesDisinfection of clinical thermometer.Disinfection of clinical thermometer.Disinfection of the skin – Venupuncture Disinfection of the skin – Venupuncture

ALDEHYDESALDEHYDESFormaldehyde & Glutaraldehyde are Formaldehyde & Glutaraldehyde are

frequently usedfrequently usedFormaldehyde is bactericidal, sporicidal & Formaldehyde is bactericidal, sporicidal &

has a lethal effect on viruses.has a lethal effect on viruses.Glutaraldehyde is effective against Glutaraldehyde is effective against

Tubercle bacilli, fungi and virusesTubercle bacilli, fungi and viruses

USESUSES

FORMALDEHYDEFORMALDEHYDETo preserve anatomical specimens To preserve anatomical specimens Destroying Anthrax spores in hair and Destroying Anthrax spores in hair and

woolwool10% Formalin+0.5% Sodium tetra borate 10% Formalin+0.5% Sodium tetra borate

is used to sterilise metal instrumentsis used to sterilise metal instruments

USESUSES

GLUTARALDEHYDEGLUTARALDEHYDEUsed to treat corrugated rubber Used to treat corrugated rubber

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

DYESDYES

Two groups of dyes are usedTwo groups of dyes are used

Aniline dyesAniline dyes

Acridine dyesAcridine dyes

ANILINE DYESANILINE DYES

Are Brilliant green, Malachite green & Are Brilliant green, Malachite green & Crystal violetCrystal violet

Active against Gram positive bacteriaActive against Gram positive bacteria

No activity against tubercle bacilliNo activity against tubercle bacilli

ACRIDINE DYESACRIDINE DYES

Acridine dyes in use are orange in colourAcridine dyes in use are orange in colour

Effective against Gram positive than Gram Effective against Gram positive than Gram negativenegative

Important dyes are Proflavine, Important dyes are Proflavine, Acriflavine,Euflavine Acriflavine,Euflavine

HALOGENSHALOGENS IodineIodine in aqueous and alcoholic solution in aqueous and alcoholic solution

has been used widely as a skin has been used widely as a skin disinfectantdisinfectant

Actively bactericidal with moderate against Actively bactericidal with moderate against spores spores

ChlorineChlorine and its compounds have been and its compounds have been used as disinfectants in water supplies & used as disinfectants in water supplies & swimming poolsswimming pools

PHENOLSPHENOLSObtained by distillation of coal tarObtained by distillation of coal tarPhenols are powerful microbicidal Phenols are powerful microbicidal

substancessubstancesPhenolic derivatives have been widely Phenolic derivatives have been widely

used as disinfectants for various purposes used as disinfectants for various purposes in hospitalsin hospitals

Eg: Lysol, cresolEg: Lysol, cresol

USESUSES

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

Aqueous solutions are used in treatment Aqueous solutions are used in treatment of woundsof wounds

GASESGASES

Ethylene OxideEthylene OxideColourless ,Highly penetrating gas Colourless ,Highly penetrating gas

with a sweet ethereal smell.with a sweet ethereal smell.Effective against all types of Effective against all types of

microorganisms including viruses microorganisms including viruses and sporesand spores

USESUSESSpecially used for sterilising heart-lung Specially used for sterilising heart-lung

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

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

FORMALDEHYDE GASFORMALDEHYDE GAS

Widely employed for fumigation of Widely employed for fumigation of operation theatres and other roomsoperation theatres and other rooms

BETA PROPIOLACTONEBETA PROPIOLACTONEUsed in fumigationUsed in fumigation

For sterilisation 0.2% BPL is usedFor sterilisation 0.2% BPL is used

Has a rapid biocidal activityHas a rapid biocidal activity

Very effective against virusesVery effective against viruses

SURFACE ACTIVE AGENTSSURFACE ACTIVE AGENTS AND AND METALLIC SALTSMETALLIC SALTS

Substances which reduce the surface Substances which reduce the surface tension – tension –

Surface active agentsSurface active agents

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

Markedly bactericidal, active against Gram Markedly bactericidal, active against Gram positive organisms.positive organisms.

No action on spores, tubercle bacilli, No action on spores, tubercle bacilli, virusesviruses

METALLIC SALTSMETALLIC SALTS

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

Act by coagulating proteinsAct by coagulating proteins

Marked bacteriostatic, weak bactericidal Marked bacteriostatic, weak bactericidal and limited fungicidal activityand limited fungicidal activity

Sterilisation by filtrationSterilisation by filtration Filtration helps to remove bacteria from heat Filtration helps to remove bacteria from heat

labile liquids such as sera and solutions of labile liquids such as sera and solutions of sugar, Antibioticssugar, Antibiotics..

The following filters are usedThe following filters are usedCandle filtersCandle filtersAsbestos filtersAsbestos filtersSintered glass filterSintered glass filterMembrane filtersMembrane filters

CANDLE FILTER

CANDLE FILTERSCANDLE FILTERSWidely used for purification of waterWidely used for purification of water

Two typesTwo types(a) Unglazed ceramic filter – Chamberland (a) Unglazed ceramic filter – Chamberland filterfilter

(b) Diatomaceous earth filters – Berkefeld (b) Diatomaceous earth filters – Berkefeld filterfilter

SEITZ FILTER

ASBESTOS DISCS

ASBESTOS FILTERASBESTOS FILTERDisposable single use discsDisposable single use discs

High adsorbing tendencyHigh adsorbing tendency

Carcinogenic Carcinogenic Eg: Seitz filterEg: Seitz filter

SINTERED GLASS FILTER

SINTERED GLASS FILTERSINTERED GLASS FILTER

Prepared by heat fusing powdered glass Prepared by heat fusing powdered glass particles of graded sizeparticles of graded size

Cleaned easily, brittle, expensive.Cleaned easily, brittle, expensive.

MEMBRANE FILTER

MEMBRANE FILTERSMEMBRANE FILTERSMade of cellulose esters or other polymersMade of cellulose esters or other polymers

Uses Uses Water purification & analysisWater purification & analysisSterilization & sterility testing Sterilization & sterility testing Preparation of solutions for parenteral usePreparation of solutions for parenteral use

RADIATIONRADIATION

Two types of radiations are usedTwo types of radiations are used

NON –IONISINGNON –IONISINGIONISINGIONISING

Non- Ionising radiationNon- Ionising radiation::Electromagnetic rays with longer wavelength Electromagnetic rays with longer wavelength

Absorbed as heatAbsorbed as heat

Can be considered as hot air sterilisationCan be considered as hot air sterilisation

Used in rapid mass sterilisation of prepacked Used in rapid mass sterilisation of prepacked Syringes and cathetersSyringes and catheters

Eg: UV raysEg: UV rays

IONISING RADIATIONSIONISING RADIATIONS

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

High penetrative powerHigh penetrative power

No appreciable increase in the No appreciable increase in the temperature – temperature – COLD STERILISATIONCOLD STERILISATION

Sterilise plastics Syringes, catheters, Sterilise plastics Syringes, catheters, grease fabrics metal foilsgrease fabrics metal foils

ULTRASONIC AND SONIC VIBRATIONULTRASONIC AND SONIC VIBRATION

Bactericidal Bactericidal

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

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