sterilization 2
TRANSCRIPT
STERILIZATIONSTERILIZATION&&
DISINFECTIONDISINFECTION
PRESENTER –DR ANSHUPRESENTER –DR ANSHU
J.SS. MEDICAL COLLEGEJ.SS. MEDICAL COLLEGE
MYSOREMYSORE
DefinitionsDefinitions
• Sterilization-defined as the process by which an Sterilization-defined as the process by which an article, surface or medium is freed of all micro article, surface or medium is freed of all micro organisms either in the vegetative or spore stateorganisms either in the vegetative or spore state
• Disinfection-defined as destruction or removal of Disinfection-defined as destruction or removal of all pathogenic organismsall pathogenic organisms
• Decontamination-refers to the process of rendering Decontamination-refers to the process of rendering an article or area free of danger from an article or area free of danger from contaminants,includin g contaminants,includin g microbial,chemical,radioactive & other hazardsmicrobial,chemical,radioactive & other hazards
• Bactericidal agents or germicides-are chemicals Bactericidal agents or germicides-are chemicals which are able to kill bacteriawhich are able to kill bacteria
• Bacteriostatic agents-are chemicals that only Bacteriostatic agents-are chemicals that only prevent the multiplication of bacteria which may, prevent the multiplication of bacteria which may, however remain alivehowever remain alive
• Antisepsis-The term “antisepsis” is used to indicate Antisepsis-The term “antisepsis” is used to indicate the prevention of infection,usually by inhibiting the the prevention of infection,usually by inhibiting the growth of bacteria in wounds or tissuegrowth of bacteria in wounds or tissue
• Antiseptics-chemical disinfectants that can be Antiseptics-chemical disinfectants that can be safely applied on skin or mucous membrane & safely applied on skin or mucous membrane & used to prevent infection by inhibiting the growth used to prevent infection by inhibiting the growth of bacteriaof bacteria
Applications in Applications in microbiology microbiology laboratory laboratory• Sterilization of culture media, reagents & Sterilization of culture media, reagents &
equipments before their use in laboratoryequipments before their use in laboratory
• Effective decontamination of spillage,surfaces & Effective decontamination of spillage,surfaces & equipment after useequipment after use
• Disinfection of contaminated material before their Disinfection of contaminated material before their safe disposal from laboratory safe disposal from laboratory
PHYSICAL METHODS OF STERILIZATIONPHYSICAL METHODS OF STERILIZATION
HEAT:considered to be the most reliable method for HEAT:considered to be the most reliable method for articles that can withstand heatarticles that can withstand heat
Dry heat Moist heatDry heat Moist heatM.O.A.-M.O.A.- Dry Heat- Protein denaturation,Dry Heat- Protein denaturation, Oxidative damage,Oxidative damage, Toxic effects of elevated levels of Toxic effects of elevated levels of electolytes electolytes Moist Heat-Coagulation & denaturation of protein Moist Heat-Coagulation & denaturation of protein Thermal death timeThermal death time-Minimum time reqd to kill a -Minimum time reqd to kill a
suspension of organisms at a predetermined suspension of organisms at a predetermined temperature in a specific environment temperature in a specific environment
Factors affecting sterilization by heatFactors affecting sterilization by heat
• Nature of heat-Moist heat is more effective than dry heatNature of heat-Moist heat is more effective than dry heat
• Temp&time-Temp is inversely proportional to time. Temp&time-Temp is inversely proportional to time.
As temp increases,time taken decreasesAs temp increases,time taken decreases
• Number of microorganism-More the no. of organisms,higher Number of microorganism-More the no. of organisms,higher the temp.or longer the duration reqd the temp.or longer the duration reqd
• Nature of micro-organism-Spores are highly resistant to heatNature of micro-organism-Spores are highly resistant to heat
• Type of material-Heavily contaminated articles req higher Type of material-Heavily contaminated articles req higher temp or prolonged exposuretemp or prolonged exposure
Certain heat sensitive articles must be sterilized at lower Certain heat sensitive articles must be sterilized at lower temptemp
• Presence of organic material [protein,sugar,oils,fat]-Increases Presence of organic material [protein,sugar,oils,fat]-Increases the time reqdthe time reqd
Dry HeatDry Heat
METHODMETHOD ARTICLE ARTICLE STERILIZEDSTERILIZED
LIMITATIONSLIMITATIONS
A)RED HEATA)RED HEAT Bacteriological Bacteriological loops,straight loops,straight wires,tips of wires,tips of forceps,searing forceps,searing spatulas spatulas
Only for those Only for those articles that can be articles that can be heated to redness in heated to redness in flameflame
B)FLAMINGB)FLAMING Scalpels,Scalpels,
mouth of test tubes,mouth of test tubes,
flasks, glass slides,flasks, glass slides,
coverslipscoverslips
•only for articles that only for articles that can be exposed to can be exposed to flame, no guarantee flame, no guarantee of killing spores,of killing spores,
Cracking of Cracking of glassware may occur glassware may occur
C)INCINERATIOC)INCINERATIONN
Soiled Soiled dressings,animal dressings,animal carcasses,pathologicarcasses,pathological material,beddingcal material,bedding
Technique results in Technique results in loss of article,only loss of article,only suitable suitable for suitable suitable for the articles that have the articles that have to be disposedto be disposed
HOT AIR OVENHOT AIR OVEN
HOT AIR OVENHOT AIR OVEN• Most widely used method of sterilizationMost widely used method of sterilization by dry by dry
heatheatPrinciplePrinciple--• Articles to be sterilized are exposed to high Articles to be sterilized are exposed to high
temp.for a duration of one hour in an electrically temp.for a duration of one hour in an electrically heated ovenheated oven
• Since air is a poor conductor of heat ,even Since air is a poor conductor of heat ,even distribution of heat throughout the chamber is distribution of heat throughout the chamber is achieved by fanachieved by fan
• Heat is transferred to the article by radiation, Heat is transferred to the article by radiation, conduction & convection conduction & convection
Sterilization cycle-Sterilization cycle-Time taken for articles to reach sterilizing temp Time taken for articles to reach sterilizing temp ++Maintainence of sterilizing temp.for a defined Maintainence of sterilizing temp.for a defined
period(holding time) period(holding time) ++Time taken for articles to cool downTime taken for articles to cool down
Different temp-time relationshipDifferent temp-time relationship for for holding time:holding time:
60min at 160 degree celsius60min at 160 degree celsius
40min at 170 degree celsius40min at 170 degree celsius
20min at 180 degree celsius20min at 180 degree celsius
Increasing temp. by 10 degrees Increasing temp. by 10 degrees shortens the sterilizing time by 50% shortens the sterilizing time by 50%
Precautions during sterilization Precautions during sterilization processprocess Articles to be sterilized must be perfectly dry Articles to be sterilized must be perfectly dry
before placing them inside to avoid breakagebefore placing them inside to avoid breakageArticles must be placed at sufficient distance, so Articles must be placed at sufficient distance, so
as to allow free circulation of air in betweenas to allow free circulation of air in betweenMouths of flasks,test tubes & both ends of pipettes Mouths of flasks,test tubes & both ends of pipettes
must be plugged with cotton woolmust be plugged with cotton woolArticles such as petridishes & pipettes may be Articles such as petridishes & pipettes may be
arranged inside metal canisters& then placedarranged inside metal canisters& then placedIndividual glass articles must be wrapped in kraft Individual glass articles must be wrapped in kraft
paper or aluminium foilpaper or aluminium foilHot air oven must not opened until the temp inside Hot air oven must not opened until the temp inside
has fallen below 60*C to prevent breakage of has fallen below 60*C to prevent breakage of glasswaresglasswares
AdvantagesAdvantages Effective method of Effective method of
sterilization of heat sterilization of heat stable articlesstable articles
Articles remain dry Articles remain dry after sterilizationafter sterilization
Only method of Only method of sterilizing oils & sterilizing oils & powderspowders
DisadvantagesDisadvantagesHot air has poor Hot air has poor
penetration (poor penetration (poor conductor of heat)conductor of heat)
Cotton wool & paper Cotton wool & paper may get slightly charredmay get slightly charred
Glasses may become Glasses may become smokysmoky
Takes longer time Takes longer time compared to autoclavecompared to autoclave
Sterilization controlSterilization control
Physical - Temperature chart recorderPhysical - Temperature chart recorder
- Thermocouple - Thermocouple
Chemical- Brownie’s tube no-3 [green spot]Chemical- Brownie’s tube no-3 [green spot]
Biological- 10*6 spores of Bacillus subtilis var Biological- 10*6 spores of Bacillus subtilis var nigerniger
MOIST HEAT STERILIZATIONMOIST HEAT STERILIZATION
METHODMETHOD TEMP-TIMETEMP-TIME USESUSES ORGANISMS ORGANISMS AFFECTEDAFFECTED
PASTEURIZATIPASTEURIZATIONON
Holder method-Holder method-63*CX30min63*CX30min
Flash method-Flash method-72*C X15-20 72*C X15-20 sec f/b quickly sec f/b quickly cooling to 13*Ccooling to 13*C
Food Food & & dairy dairy industindustryry
Salmonella, Salmonella, mycobacteria, mycobacteria, streptococci, streptococci, staphylococci, staphylococci, brucella-destroyed brucella-destroyed coxiella may coxiella may survivesurvive
VACCINE BATH VACCINE BATH 60*C X1 hr60*C X1 hr ContaContaminatiminating ng bacterbacteria in ia in vaccinvaccine e preparpreparationation
Only vegetative Only vegetative bacteria are killed bacteria are killed spores survivespores survive
At temp.below 100*C
WATER BATH OR WATER BATH OR SERUM BATHSERUM BATH
56*CX1Hr on 56*CX1Hr on several several successive successive days[proteindays[proteins in the s in the serum will serum will coagulate at coagulate at higher temp]higher temp]
ContamiContaminating nating bacteria bacteria in serum in serum preparatpreparationion
only only vegetative vegetative bacteria are bacteria are killed killed spores spores survivesurvive
INSPISSATIONINSPISSATION 80-85*C X30 80-85*C X30 Min on 3 Min on 3 successive successive daysdays
Egg & Egg & serum serum containicontaining ng media media [L-J [L-J Media Media &Loeffle&Loeffler’s r’s serumserum
Day1-Day1-vegetative vegetative forms are forms are killed, spores killed, spores germinate by germinate by next day & are next day & are killed killed Success of the Success of the process process depends on depends on germination of germination of spores spores
At temp.100*CAt temp.100*CBoiling:Boiling:
• Boiling water at 100*C for 10-20 minutesBoiling water at 100*C for 10-20 minutes
• Articles-certain metal articles & glasswaresArticles-certain metal articles & glasswares
• Most vegetative bacteria and viruses are killed immediatelyMost vegetative bacteria and viruses are killed immediately Not effective against - Bacterial toxinsNot effective against - Bacterial toxins
- spores- sporesSteam at 100*CSteam at 100*C
• Principle Principle :Exposing articles to free steam at 100*C:Exposing articles to free steam at 100*C
• Eg-Arnold’s and Koch’s steamerEg-Arnold’s and Koch’s steamer
An Autoclave (with discharge tap open)An Autoclave (with discharge tap open)
• Exposure period- 90 minutesExposure period- 90 minutes
• Uses-Media such as TCBS, DCA, Selenite brothUses-Media such as TCBS, DCA, Selenite broth
Tyndallisation Tyndallisation OR OR Fractional sterilization OR Intermittent Fractional sterilization OR Intermittent sterilizationsterilization
Sugar and gelatin in the medium may get Sugar and gelatin in the medium may get decomposed on autoclaving, hence they are decomposed on autoclaving, hence they are exposed to free steaming for 20min on 3 exposed to free steaming for 20min on 3 successive dayssuccessive days
Success of the process depends on germination Success of the process depends on germination of sporesof spores
At temp.>100*CAt temp.>100*C
AUTOCLAVE / STEAM STERILIZATIONAUTOCLAVE / STEAM STERILIZATIONPrinciple Principle - [steam under pressure]- [steam under pressure] Water boils when its vapour pressure equals that Water boils when its vapour pressure equals that
of surrounding atmospheric pressure.of surrounding atmospheric pressure. When pressure inside the closed vessel When pressure inside the closed vessel
increases,the temp at which water boils also increases,the temp at which water boils also increasesincreases
At a pressure of 15Lbs inside autoclave, the temp At a pressure of 15Lbs inside autoclave, the temp is said to be 121*Cis said to be 121*C
Exposure of articles to this temp for 15 minutes Exposure of articles to this temp for 15 minutes sterilizes themsterilizes them
Articles sterilizedArticles sterilized
• Culture mediaCulture media
• Hospital dressingsHospital dressings
• LinenLinenAdvantages of steamAdvantages of steam::
• More penetrative More penetrative power than steampower than steam
• Moistens Moistens spores[essential for spores[essential for coagulation of proteins]coagulation of proteins]
Different types of Different types of autoclave:autoclave:
• Simple pressure Simple pressure cooker typecooker type
• Steam jacketed Steam jacketed downward downward displacement displacement laboratory autoclavelaboratory autoclave
• High pressure High pressure
pre-vaccum autoclavepre-vaccum autoclave
PrecautionsPrecautions
Articles should not be tightly packedArticles should not be tightly packed Autoclave must not be overloadedAutoclave must not be overloaded Air discharge must be complete and there should Air discharge must be complete and there should
not be any residual air trapped insidenot be any residual air trapped inside Caps of bottles & flasks should not be tightCaps of bottles & flasks should not be tight Autoclave must not be opened until the pressure Autoclave must not be opened until the pressure
has fallen else the contents will boil overhas fallen else the contents will boil over Articles must be wrapped in paper to prevent Articles must be wrapped in paper to prevent
drenchingdrenching Bottles must not be overfilledBottles must not be overfilled
Advantages Advantages DisadvantagesDisadvantages
Very effective way of Very effective way of sterilizationsterilization
Quicker than hot air Quicker than hot air ovenoven
Drenching and wetting Drenching and wetting of articlesof articles
Trapped air may Trapped air may reduce efficacyreduce efficacy
Takes long time to Takes long time to coolcool
Sterilization control Sterilization control
PHYSICAL : Automatic process controlPHYSICAL : Automatic process control
ThermocoupleThermocouple
Temperature chart recorderTemperature chart recorderCHEMICAL: Brownie’s tube no 1[black spot]CHEMICAL: Brownie’s tube no 1[black spot]
Succinic acid(Melting point -121*C)Succinic acid(Melting point -121*C)
Bowie’s Dick tape(satisfactory Bowie’s Dick tape(satisfactory
process-dark brown stripes)process-dark brown stripes)BIOLOGICAL: 10*6 spores of GeobacillusBIOLOGICAL: 10*6 spores of Geobacillus
stearothermophillusstearothermophillus
RADIATIONRADIATIONNON-IONISING RADIATIONNON-IONISING RADIATION
U.V. RAYSU.V. RAYS[200-280nm]:260nm most effective[200-280nm]:260nm most effective M.O.A.-Formation of thymine-thymine dimersM.O.A.-Formation of thymine-thymine dimers Inhibition of D.N.A replicationInhibition of D.N.A replication Uses-to disinfect hospital wards,operation theatres,virus Uses-to disinfect hospital wards,operation theatres,virus
laboratorieslaboratories Limitation:do not kill sporesLimitation:do not kill spores Disadvantages : Low penetrative powerDisadvantages : Low penetrative power Limited life of U.V. bulbLimited life of U.V. bulb Some bacteria have D.N.A.repair enzymesSome bacteria have D.N.A.repair enzymes overcome damageovercome damage Organic matter and dust prevents its reachOrganic matter and dust prevents its reach Rays are harmful to skin & eyesRays are harmful to skin & eyes Doesn’t penetrate papers, plastics or glassDoesn’t penetrate papers, plastics or glass
INFRA-RED RAYSINFRA-RED RAYS
M.O.A.- Generation of heatM.O.A.- Generation of heat Temp 180*C X 7.5 minutesTemp 180*C X 7.5 minutes
Articles sterilized : metallic instruments, Articles sterilized : metallic instruments, glasswaresglasswares
Mainly used in central sterile supply departmentMainly used in central sterile supply department
Sterilization control:Brownie’s tube no.4(blue Sterilization control:Brownie’s tube no.4(blue spot)spot)
IONIZING RAYS IONIZING RAYS [COLD STERILIZATION[COLD STERILIZATION]]
Particulate [electron Particulate [electron beams]beams]
Syringes, gloves ,dressing Syringes, gloves ,dressing packs ,food & packs ,food & pharmaceuticalspharmaceuticals
Few seconds onlyFew seconds only
DisadvantagesDisadvantages--
Poor penetrative power,req Poor penetrative power,req sophisticated equipmentssophisticated equipments
Not widely used in Not widely used in medicinemedicine
Electromagnetic Electromagnetic rays[Gamma rays & X rays[Gamma rays & X rays]rays]
Damage nucleic acid of Damage nucleic acid of microorganismmicroorganism
Used comercially to Used comercially to sterilize disposable sterilize disposable petridishes, plastic petridishes, plastic syringes, antibiotics, syringes, antibiotics, vitamins & hormonesvitamins & hormones
Dose of 2.5 megarads kills Dose of 2.5 megarads kills all bacteria. fungi,viruses & all bacteria. fungi,viruses & sporesspores
Longer time of exposureLonger time of exposure Disadvantages: can’t be Disadvantages: can’t be
switched off, glasswares switched off, glasswares become brownish, loss of become brownish, loss of tensile strength of fabricstensile strength of fabrics
FILTRATIONFILTRATION
To remove microbes To remove microbes from heat labile from heat labile liquids :Serumliquids :Serum
Antibiotic solutionsAntibiotic solutions Sugar solutionSugar solution Urea solutionUrea solution• Applications:Applications: Removing Removing bacteria from bacteria from
ingredients of culture ingredients of culture media,media,
• Preparing suspensions Preparing suspensions of viruses,of viruses,
• Water purification Water purification
Types of filterTypes of filter:: Earthenware filtersEarthenware filters Pasteur-Pasteur-
ChamberlandChamberland BerkefeldBerkefeld MandlerMandler Asbestos filtersAsbestos filters Sintered glass filterSintered glass filter Membrane filterMembrane filter
AIR FILTERSAIR FILTERS
Air can be filtered using Air can be filtered using HEPA [High efficiency particle HEPA [High efficiency particle air filter]air filter]
99.97%efficient for removing particles >0.3micrometers 99.97%efficient for removing particles >0.3micrometers in diameterin diameter
ApplicationsApplications:Rooms having severe neutropenic patients,:Rooms having severe neutropenic patients,
Operating rooms for orthopaedic implant procedureOperating rooms for orthopaedic implant procedure
Efficiency tested Efficiency tested : Dioctylphthalate (DOP) particle test : Dioctylphthalate (DOP) particle test using particles that are 0.3 micrometers in diameterusing particles that are 0.3 micrometers in diameter
Chemical MethodsChemical Methods
Ideal disinfectant :Ideal disinfectant : should have should have• Wide spectrum of activityWide spectrum of activity• Destroy microbes within practical period of timeDestroy microbes within practical period of time• Active in the presence of organic matterActive in the presence of organic matter• Active at any pHActive at any pH• StableStable• Long shelf lifeLong shelf life• High penetrating powerHigh penetrating power• Non-toxic, non-allergenic, non-irritative or non-Non-toxic, non-allergenic, non-irritative or non-
corrosivecorrosive
• Should not have bad odourShould not have bad odour
• Should not leave non-volatile residue or stainShould not leave non-volatile residue or stain
• Efficacy should not be lost on reasonable dilutionEfficacy should not be lost on reasonable dilution
• Should not be expensiveShould not be expensive
• Easily availableEasily available
Factors determining potency of Factors determining potency of disinfectantdisinfectant
• Concentration of substanceConcentration of substance
• Time of actionTime of action
• pH of the mediumpH of the medium
• TemperatureTemperature
• Nature of organismNature of organism
• Presence of extraneous materialPresence of extraneous material
CLASSIFICATION OF DISINFECTANTSCLASSIFICATION OF DISINFECTANTS
A)Based on consistencyA)Based on consistency
Liquid Liquid [Alcohols,Phenol][Alcohols,Phenol]
Gaseous Gaseous [Formaldehyde [Formaldehyde vapour,Ethylene vapour,Ethylene oxide]oxide]
B)Based on spectrum of B)Based on spectrum of activityactivity
High levelHigh level
Intermediate levelIntermediate level
Low levelLow level
C)Based on mechanism of actionC)Based on mechanism of action
• Action on membrane[Alcohol, Detergents]Action on membrane[Alcohol, Detergents]
• Denaturation of cellular proteins[Alcohol, Denaturation of cellular proteins[Alcohol, Phenol]Phenol]
• Oxidation of essential groups of Oxidation of essential groups of enzymes[Halogen,H2O2]enzymes[Halogen,H2O2]
• Alkylation of amino, carboxyl & hydroxyl Alkylation of amino, carboxyl & hydroxyl group[Ethylene oxide,Formaldehyde]group[Ethylene oxide,Formaldehyde]
• Damage to nucleic acid [Ethylene Damage to nucleic acid [Ethylene oxide,Formaldehyde]oxide,Formaldehyde]
Spectrum of activitySpectrum of activityVegetative cells
mycobacteria
spores fungi viruses
examples
High level
+ + + + + Ethylene oxide,Gluteraldehyde,Formaldehyde
Intermediate level
+ + - + + Phenolics,Halogens
Low level
+ - - + +/- Alcohols,Quaternary ammonium compounds
Alcohols Alcohols
Ethyl alcohol & isopropyl alcohol[preferred] Ethyl alcohol & isopropyl alcohol[preferred] M.O.A.-Denaturation of bacterial proteinsM.O.A.-Denaturation of bacterial proteins Concentration of 60-90% in waterConcentration of 60-90% in water No action on sporesNo action on spores Application-Disinfection of clinical thermometersApplication-Disinfection of clinical thermometers Methyl alcohol-Effective against fungal spores,Methyl alcohol-Effective against fungal spores,
To treat cabinets & incubators To treat cabinets & incubators affected byaffected by
themthem
Aldehydes Aldehydes
FormaldehydeFormaldehyde
• Active against amino group Active against amino group in protein moleculein protein molecule
• Bactericidal,sporicidal,lethal Bactericidal,sporicidal,lethal effects on viruseseffects on viruses
• Applications-Applications-Preserve anatomical Preserve anatomical
specimensspecimens10% formalin containing 10% formalin containing
0.5%sodium tetraborate is 0.5%sodium tetraborate is used to sterilize metal used to sterilize metal instrumentsinstruments
GlutaraldehydeGlutaraldehyde
• Specially effective against Specially effective against tubercle bacilli,fungi & tubercle bacilli,fungi & virusesviruses
• Application-Application-Corrugated rubber Corrugated rubber
anaesthetic tubes,face anaesthetic tubes,face masks,plastic ET Tube, metal masks,plastic ET Tube, metal instruments,cystoscopes,broinstruments,cystoscopes,bronchoscopesnchoscopes
Less toxic & irritant to eyes Less toxic & irritant to eyes & skin than formaldehyde& skin than formaldehyde
DyesDyes
• Aniline dyes Acridine dyesAniline dyes Acridine dyesBrilliant green ProflavineBrilliant green Proflavine
Malachite green AcriflavineMalachite green Acriflavine
Crystal violet Euflavine Crystal violet Euflavine
AminacrineAminacrine
• Mainly bacteriostatic, low bactericidal activityMainly bacteriostatic, low bactericidal activity
• No activity against tubercle bacilli, hence the use of No activity against tubercle bacilli, hence the use of malachite green in L-Jmediamalachite green in L-Jmedia
• More effective against gram positive bacteria than gram More effective against gram positive bacteria than gram negative bacterianegative bacteria
• Use-Skin & wound antisepticsUse-Skin & wound antiseptics
HalogensHalogens
IodineIodine
• Skin disinfectantSkin disinfectant
• Actively Actively bactericidal,with bactericidal,with moderate action moderate action against sporesagainst spores
• Active against Active against tubercle bacilli & tubercle bacilli & virusesviruses
Chlorine[hypochlorites]Chlorine[hypochlorites]
• Markedly bactericidalMarkedly bactericidal
• Wide spectrum of Wide spectrum of action against virusesaction against viruses
• Organic chloramine-Organic chloramine-antiseptics for antiseptics for dressing woundsdressing wounds
PhenolsPhenols
• Lysol,cresol,chlorophenols,chloroxyphenols,chlorhLysol,cresol,chlorophenols,chloroxyphenols,chlorhexidineexidine
• M.O.AM.O.A.-cell membrane damage.-cell membrane damagerelease cell release cell contentscontents lysis lysis
Precipitate proteinPrecipitate protein Inactivation of membrane bound oxidases & Inactivation of membrane bound oxidases &
dehydrogenases dehydrogenases
• Chlorhexidine-skin antisepticChlorhexidine-skin antiseptic
• Most effective against gram positive organismsMost effective against gram positive organisms
GasesGases
Ethylene oxide Formaldehyde gas
Betapropiolactone
Alkylating the amino, carboxyl,hydroxyl & sulphydryl gps in protein moleculeReacts with DNA & RNAApplications-Heart-lung machines,ventilators,sutures,dental equipmentsEffective against all type of microorganisms including viruses and sporesMutagenic & carcinogenic
Alkylation of amino group
Applications- Operation theatres,sick rooms,laboratories
Alkylation of carboxyl & hydroxyl groups
More efficient than formaldehyde for fumigation
Active against all organisms & virusescarcinogenic
Surface active agentsSurface active agents
• M.O.AM.O.A.- Alter the energy relationship at interface .- Alter the energy relationship at interface producing a reduction of surface or interfacial tensionproducing a reduction of surface or interfacial tension
• Most important are cationic surface active agents in the Most important are cationic surface active agents in the form of quaternary ammonium compoundsform of quaternary ammonium compounds
[acetyl,trimethylammonium bromide(CETAVLON OR [acetyl,trimethylammonium bromide(CETAVLON OR CETRIMIDE)]CETRIMIDE)]
• Bactericidal, more active against gram positive bacteriaBactericidal, more active against gram positive bacteria
• No action on spores, tubercle bacilli,& most virusesNo action on spores, tubercle bacilli,& most viruses
• Disadvantage- Disadvantage- Pseudomonas can metabolise Pseudomonas can metabolise cetrimide,using them as a carbon, nitrogen & energy cetrimide,using them as a carbon, nitrogen & energy sourcesource
Metallic saltsMetallic salts
• Salts of silver, copper and mercurySalts of silver, copper and mercury
• M.O.AM.O.A.-protein coagulation.-protein coagulation
• Capacity to combine with free sulphydryl group of Capacity to combine with free sulphydryl group of cell enzymescell enzymes
• Thiomersal,phenylmercury nitrate & Thiomersal,phenylmercury nitrate & mercurochrome-mild antisepticsmercurochrome-mild antiseptics
• Marked bacteriostatic actionMarked bacteriostatic action
• Copper salts -fungicidesCopper salts -fungicides
Testing of DisinfectantsTesting of Disinfectants
• No single test is available to determine the No single test is available to determine the efficiency of a disinfectantefficiency of a disinfectant
• Different methods-Different methods- Koch’s methodKoch’s method Rideal walker methodRideal walker method Chick Martin testChick Martin testKelsey-Sykes test [capacity to use dilution test]Kelsey-Sykes test [capacity to use dilution test]I n-use testI n-use test
NEWER METHODS OF NEWER METHODS OF STERILIZATION AND STERILIZATION AND DISINFECTIONDISINFECTION
Process Agent
Disinfection
Ortho-phthaladehyde(Cidex OPA)Antimicrobial coating(Surfacine)Superoxide water(Sterilox)
Sterilization
Liquid sterilization process(Endoclens)Rapid readout ethylene oxide biological indicator(Attest)New plasma sterilizer(Sterrad 50)
COMPARISON OF NEW AND STANDARD COMPARISON OF NEW AND STANDARD DISINFECTION & STERILIZATION DISINFECTION & STERILIZATION TECHNOLOGIESTECHNOLOGIES
New Standard Advantages Disadv. Future needs
OPA Glutaralehyde
Shorter process time(12vs45min)No activationNot a known irritant to eyes pr nasal passagesNo vapour ceiling limitWeak odour
Stains protein grayHigher cost
Additional studies of antimicrobial efficacyCost-effectiveness studiesStudy of effectiveness in actual clinical useVerification of more cycles per solution than glutaraldehyd
Surfacine
Disinfectants (phenolics,quaternary ammonium)Antiseptics (alcohol,chlorhexidine)
Antimicrobial persistance (>13days)May be used on animate or inanimate objectsBroad antimicrobial spectrumNo toxigenicity to mammalian cellTransfers active agent (silver) to microbes on demand without elution
Cost?
Assess microbicidal activity against broad spectrum of pathogensDemonstration of efficacy to reduce nosocomial infectionHuman safety & toxicity data for use as an antisepticDemonstrate antimcrobial activity in presence of organic matter
Superoxide water
High or low level disinfectants;antiseptics
Basic materials (saline & electricity)inexpensiveEnd product not damaging to environmentNon toxic to biological tissues
Production equipment inexpensive due to monitoringDecreased efficacy in presence of organic matterLimited use life(must be freshly prepared)
Cost-effectiveness study
Endoclens
None
Device automatically cleans & sterilizesRapid cycle time(<30min)Tests endoscope for channel blockage &leaksAdvantages of automated process(consistant exp. to sterilant,operator convenience)
•Cost?•Used for immersible in struments only•No long term storage
•Cost.effectiveness study•Study of eff. In actual clinical use•Assessment of microbicidal activity
EO rapid read out
48-hr spore readout biological indicator
Rapid(4hr)reliable assessment of sterilizationn efficacyPrevents recall of released sterilization loads
Cost?Not tested with EO and CO2 mixtures
Cost-effectiveness studyValidation of claimed 100% sensitivity
Plasma sterilizer
Hydrogen peroxide gas plasma sterilizer
Use of two H2O2 diffusion plasma stage cycles is a more effective sterilization processReduced cycle timeVarious sized units availableLeaves no toxic residue
Cost?Endoscopes with length >40cm or diameter<3mm cannot be processed
Cost-effectivenes studyStudy of effectiveness in actual practice
Conclusion Conclusion
• Various methods of sterilization & disinfection are Various methods of sterilization & disinfection are availableavailable
• Use of a particular method depends upon the Use of a particular method depends upon the article to be sterilized and nature of article to be sterilized and nature of microorganismmicroorganism
• Newer sterilization and disinfection technologies Newer sterilization and disinfection technologies may provide significant advantages over existing may provide significant advantages over existing technologiestechnologies
• These new technologies hold the promise of These new technologies hold the promise of improved patient careimproved patient care
ReferencesReferences
** Practical Medical Microbiology,Practical Medical Microbiology,
Mackie & McCartney,14Mackie & McCartney,14thth edition edition
** Text book of Microbiology, Text book of Microbiology,
Ananthnarayan & Paniker’s,8Ananthnarayan & Paniker’s,8thth edition edition
** Internet sources Internet sources
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