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STERILIZATION AND
ASEPSIS IN MINORORAL SURGERY
PRESENTATION BY
DEEPTHA.J
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WHAT IS STERILIZATION ?
STERILIZATION : It is defined as the process by which
an article, surface and medium isfreed of all microorganisms either invegetative or spore state.
Patterson 1932: a process by which allmicrobial forms are destroyed.
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WHAT IS DISINFECTION?
Means destruction of all pathogenicmicroorganisms, or organisms capable ofgiving raise to infection.
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WHY STERILIZATION ?
According to the GERM THEORY OF DISEASE,micro-organisms are cause for infectious disease
Since the days of PASTEUR, thousands of pathogenicor disease causing micro-organisms have beenidentified.
BACTERIA, FUNGI, VIRUS, PROTOZOA are
examples of harmful micro-organisms.
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WHY STERILIZATION ?contd
To avoid introducing new micro-organisms insurgical field
pathogenic micro-organisms introduced intowound
blood streamwound breakdown
delayed healing
To prevent cross-contamination
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WHY STERILIZATION ?contd
Patient Operator
Other personnel
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CHAIN OF INFECTION
Pathogen
Source
ModeEntry
SusceptibleHost
(sufficient virulence& adequate numbers)
(allows pathogen tosurvive & multiply)
(of transmissionfrom source to host)
(i.e., one that is not immune)
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WHY STERILIZATIONcontd
INFECTIOUS DISEASEVIRAL -HIV [ AIDS ]
- HEPATITIS- HERPES Innoculation
- PAPILLOMA- MUMPS, MEASLES, RUBEOLA - Inhalation
BACTERIA TUBERCULOSIS-Inhalation- LEGIONNERES DISEASE
( THRO INFECTED AEROSOLS)-CORNEBACTERIUM-TREPONEMA
FUNGI - CANDIDA- PNEUMOCYSTITIS CARNII
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NEED FOR STERILIZATION
HEPATITIS A,B,C,D,E,F,G. Vaccination against hbv only available !!!
Broad spectrum antibiotics- unjustified security
PROTECT YOURSELF!!
HENCE STERILIZATION IS THE ONLY SIMPLECOST EFFECTIVE WAY TO REDUCE MICROBIALLOAD.
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HOW TO STERILIZE ?
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Cannot autoclave patients
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CLASSIFICATION OF VARIOUS STERILIZATION
AGENTS
A) Physical agents1) Sunlight
2) Drying
3) Dry heat : Flaming
Incineration
Hot air
4) Moist heat : Pasteurization
Boiling
Steam under normal pressure
Steam under pressure
5) Filtration : Candles
Asbestos pads
Membranes
6) Radiation : ultra
violet radiationIonizing radiation
7) Ultrasonic and sonic vibrations
B) Chemicals1. Alcohols : Ethyl, isopropyl,
methyl.
2. Aldehydes : Formaldehyde
Glutaraldehyde
3. Dyes4. Halogens
5. Phenols
6. Surfaceactive agents
7. Metallic salts
8. Gases : Ethylene oxide,
formaldehyde,
beta propiolactone
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CAN INSTRUMENTS GO STRAIGHTINTO THE STERILIZER ?
Pre soaking of instruments.
Pre sterilization cleaning
-manual
-ultrasonic
Packaging
journal of dental practice-vol5-mar06
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(HOLDING/PRESOAKING)
Keeps instruments wet.
Prevents drying of saliva &blood on the
instruments. - Lawrence & Block 1968 Facilitating easy cleaning.
solution used may be phenol orglutaraldehyde.
Not more than few hours-corrosion
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PRE-CLEANING1. Ultrasonic processing2. Manual cleaning
Advantage of Ultrasonic processing Increased efficiency in obtaining a high degree of cleanliness.
Reduced danger to clinician from direct contact with potentialpathogenic microorganisms. Improved effectiveness for disinfection Elimination of possible dissemination of microorganisms through
release of aerosols and droplets, which can occur during scrubbingprocess.
Penetration into areas of the instruments where the bristles of a
brush may be unable to contact. Removal of tarnish.Manual cleansing
Ultrasonic processing is the method of choice, but when manualcleaning is the only alternative, precaution must be taken toprevent contamination
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PACKING
Prevents post- sterilization contaminationPacking material :
A singlelayerclothwrap - steam sterilization ,
selfsealingpolyfilm pouches- chemical vapoursterilization, paperwrap-dry heat sterilization.
Tested by placing spore strips inside thematerial and then processed thro sterilizer,ensuring that the spores are killed.
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SPAULDINGSCLASSIFICATION
Who Was Spaulding?
In the mid-1960s Dr. Earl Spauldingdeveloped a framework for sterilization.
The system is based on the patient'srisk for infection that various types of
instrument or equipment contact cancreate.
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CLASSIFICATION OF INSTRUMENTSTERILIZATION -CDC
The categorization of instrument depends on the contact withdifferent tissue types to determine whether sterilization /disinfection is required. The categories are as follows.
1. Critical items :
Instrument that touches sterile areas of the body enterthe vascular system and those that penetrates the oralmucosa. Eg : scalpel, curettes, burs
2. Semi critical items :
Instrument that touches mucous membrane and oral fluids
but do not penetrate tissue, Eg.: saliva ejectors, radiograph,bite blocks, mouth mirrors etc.
3. Non critical items :
Those items that does not come in contact with oral mucosabut are touched by saliva / blood contaminated hands whiletreating patient. Eg.: Chair light, switches, drawer pills etc.
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STERILIZATION CYCLE
The time required to achievesterilization is referred to as processcycle, which includes Heat up &/or penetration of the agent Kill time
Safety factor for bioburden
Evacuation or dissipation of the agent
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SUNLIGHT
Sunlight possess appreciable BACTERICIDALactivity ( kills HIV virus in 3-4 mins)
It is the sterilization which occurs at normal
condition The action is due to the content of uv rays
and heat Simple and Grieg showed that, in India, typhoid bacilli exposed
to the sun on pieces of white drill cloth were killed in two hours,whereas controls kept in the dark were still alive after six days.
Bacteria suspended in water are readily destroyed by exposureto sunlight.
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DRYING
Moisture is essential for the growth of bacteria.
Four-fifth by weight of the bacterial cell consists of water.
Drying in air has therefore, a deleterious effect on manybacteria.
This method is unreliable and is only of theoretical interest.spores are unaffected by drying.
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HEAT
Heat is dependable physical agent fordestruction of all forms of microbial life,including spores.
Moist heat is more effective than dry heat. The killing effect of dry heat is due to protein
denaturation, Oxidative damage & toxic effectof elevated levels of electrolytes.
Moist heat kills microorganisms by Coagulationand denaturing their enzymes and structuralproteins, a process in which water participates.
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HEAT-contd
Moist heat is effective at lower temperature.
A properly designed autoclave will effectivelysterilize media and other water containing
materials in sealed or unsealed bottles, laboratorydiscards and porous packaged materials.
Dry heat is suitable for oils, petroleum products
,oily injections talc, glasswares,beakers,flasks
Dry heat cannot be used for water containingculture media.
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DRY HEAT
a) FLAMING / RED HEAT
b) INCINERATIONc) HOT AIR OVEN.
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Advantages of dry heat
More convenient
Instruments are less likely to corrode ( dry heat is a protectivetype of sterilization )
Do not require drying after sterilization.Disadvantages of using dry heat
Much harder to kill than when they are wet.
Has very little power of penetration and unless very hightemperatures are used, the method is slow.
Instruments need a considerable time to cool after sterilizationand the temper of metal instruments may be lost
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Rate of microbial death
When bacterial populations are heated or
treated with antimicrobial chemicals, they
usually die at a constant rate.
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HOT AIR OVENPARTS
Fan Temperature indicator,
Control thermostat,
Timer,
Open mesh shelving
Wall insulation.
The oven is usually treated by electricity, withheating elements in the wall of the chamber.
Door interlocks is fitted to ensure theheating cycle will not start until the door isshut and that the door will not open while thecycle is in progress.
Arrangement of instruments should allow freecirculation of air
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TIME TEMPERATURE FOR HOTAIR OVEN
Sterilization is achieved by dry heat at
160C for 60 minutes,
170C for 15 minutes,
180C for 7 minutes,190C for 1 minutes
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PRECAUTIONS TO BEOBSERVED IN HOT AIR OVEN
Temp should not be greater than 180c.
The glassware - dry
No sudden cooling
No over loading
Free circulation of air.
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FLAMING
The articles are passed on the Bunsen flame.
Articles Sterilized: Inoculating loop of wires.
Forceps. Spatulas. Mouths of culture tubes.
All these articles are made red hot by placing them
over the Bunsen flame but articles like cover slips &glass slides which are fragile are passed betweenthe Bunsen flame for a few seconds & they arenever made red hot.
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INCINERATION
Contaminated material in bulk is sterilized& disposed by burning in an incinator.
Articles sterilized: All surgical dressings Used disposable syringes
All contaminated lab materials Animal carcass Bedding.
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MOIST HEAT
Moist heat can be employed At temperature below 100C
At a temperature of 100C
(either in boiling water / in free steam)
At a temperature above 100C
(in saturated steam under increased pressure).
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MOIST HEAT -Temperaturebelow 100C:
(a) Pasteurization of Milk:There are 3 types of methods.
Holders process Temp. is 65c for 30min Flash process Temp. 72c for 15-20 sec
& sudden cooling to 13c Ultra pasteurization- temp 82c 3 secs & sudden cooloing
(b) Vaccines of non-sporing bacteria:They are heat inactivated by placing it in special vaccine bags,
which is maintained at 60c for one hour.
(c) To sterilize serum: body fluids which contain coagulable proteins (egg yolk, synovial fluid)
sterilized by placing them in a water bath at 56c for 1 hour for severalsuccessive days.
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CONTD
(d) Certain instruments: Like spatula, cytoscopes, & otherinstruments that can be damaged by excess of heat can besterilized by keeping them in water bath at 75c for 10minutes.
(e) Certain media: Such as
Lowensteins Jensens mediawhich contains egg & other mediawhich contain sugar & gelatin by placing it in anInspissator which is maintained at 80-85c for an hour on3 successive days.
(f) Bed cloths & certain utensils used patients by can besterilized by placing them at 75c-80c for several minutestemp to ensure complete sterilization.
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TEMPERATURE AT 100C
(a)Boiling: NOT a preferred method of sterilization. Vegetative forms are killed in few minutes at 54 to 65oC.
Certain bacterial spores will withstand 115oC for 3 hours!
Boiling can destroy most of the non- sporing bacteria butfor complete destruction it should be boiled forconsiderable period (10-15mts).
Effective boiling is brought about by adding 2%sodium bicarbonate solution which will promotesterilization.
Certain metallic instruments & glassware can be
sterilized by boiling.
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CONTD
(b) Kochs & Arnolds steam sterilizer:
This apparatus consists of copperlined cabinet with perforated
tray & a conical lid, which has slightopening, which allows steam to pass out.
Works by gas or electricity.
It is used for single exposure sterilization. Articles are kept at 100c for 90 minutes.
Culture media sterilization
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TYNDALLISATION
Sterilization through intermittent exposure known astyndallisation. It was discovered by Tindal. Temp is 100cfor 20 min on 3 successive days.Advantages:
During the 1st exposure all vegetative bacteria present in
the media is killed during the next 24 hours the sporesthat are present in the media germinate. During 2nd exposure all the germinated bacteria will be
destroyed. During 3rd exposure complete sterilization is ensured.
It is mainly used to sterilize culture, media which containssugar & gelatin.
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TEMPERATURE ABOVE 100C
AUTOCLAVES- Von BremannPrinciple:
Direct saturated steam contact is the basis ofsteam sterilization. when steam comes in contact with cooler
surface, it condenses into water and gives oflatent heat to that surface. The condensed water
ensures moist conditions for killing microbes. Pressure increases the boiling temperature but it
itself does not have any effect on micro-org orsteam penetration
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TYPESI. laboratory AUTOCLAVES,II. hospital dressing sterilizers,III. rapid cooling sterilizer
I. HORIZONTALII. VERTICAL
I. N-CYCLE (gravity displacement/non vacuum/downwarddisplacement )
II. B-CYCLE ( pre vacuum )III.S-CYCLE( high speed pressure )
TEMPERATURE :121c-15lbs-15 mins126c-10 mins134c-30lbs-3 mins
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Air is heavier than steam Steam forces air out
Valve closes
CRITICAL ISSUES:
CAREFUL WRAPPING!
CAREFUL LOADING!
Heat between 121 to 134 degrees centigrade
15 minutes @ 121 C
3 minutes @ 134 C
DOWNWARD DISPLACEMENT STERILIZER
B CYCLE & S CYCLE
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B CYCLE & S CYCLEPRE-VACUUM STERILIZATION
More rapid and efficient steam penetration Pulls air (out) -- vacuum When the wrapper if carefully opened, it provides a sterile
surface for the instruments during the surgical procedure.
PRESSURISED STEAM STERILIZATION S CYCLEFLASH STERILIZATION is performed either thro gravity
displacement type or pre vacuum type non-sterile item needs to be sterilized quickly. Item is placed unwrapped in a perforated metal tray and
sterilized according to the manufacturers time and temperaturerecommendations. The sterilized items are transported to the OR in the metal tray. Difficult to deliver flash-sterilized devices aseptically (tray is
hot, wet and instruments are unwrapped
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AUTOCLAVE
Small Sterilizers
Cycle type N-cycle B-cycle S-cycle (Statim)
Materials that
can be sterilized
solid only solid/hollow solid/hollow
non-wrapped
only
multi-
wrapped/non-
wrapped
wrapped/non-
wrapped
porous
Air removal
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AUTOCLAVE
Articles sterilized: Surgical Instrument- forceps,etc Surgical Cotton All culture media except
media contain sugar & gelatin. Lab coats, rubber gloves Test tubes, enamel metal trays, Handpieces ,steel burs,tongue depressors Advantages
Easiest, safest, surest Fastest
Least expensive Automatic Many items withstand repeated processing Leaves no harmful residue
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AUTOCLAVE Disadvantages
Preparation and packageto be careful Item must be clean and freefrom grease and oil
Steam must have direct
contact with all areas of an item Timing depends on materialand load chance of human error Impurities in water (steam)
No living things can survivesaturated steam at 121oC longerthan 15 minutes. All vegetative forms are killed at 54-65c Spores can withstand 115c for more than 3 hrs
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RADIATION
It is brought about by 2 methods. Ionizing radiation
particles
gamma rays Non Ionizing radiation
uv rays
infra redmicrowaves
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IONISING RADIATION
E.g. X- rays gamma rays, cosmic rays. COLD STERILIZATION.
MECHANISM : ionic energy- thermal & chemical energy- dna
affected.
Articles sterilized: Any type of plastic disposable syringes,
catheters, all glass materials, animal feeds, cloths oils, grease, rubber material.
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NON-IONISING RADIATION
U V RAYS & INFRARED RAYS Also called hot sterilizationMECHANISM:It produces hyperthermic conditions that disrupts life
Heat affects water molecules and interferes with cellmembranes U. V. rays:
they are used to bring down the number ofmicroorganism present in air. So it is used forsterilization of Operation Theater and alsobiological safety cabinets used in the laboratory.
Dis adv: Low-penetrating power.
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INFRA RED RADIATION:
The temp attained is 180c and it is keptfor 7- min.
Article sterilized:
Certain metallic instruments Glassware.
This is usually employed in central sterile
supplying department (CSSD) in Certainhospitals.
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FILTRATION
This is used to sterilize heat labile liquid orall those liquids which are affected byincrease in temp can be sterilized.
E.g. Serum antibiotic culture &
sensitivity media containing sugars &gelatin.
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IT IS BROUGHT ABOUT BY
Candles filters Unglazed ceramic filters. Diatomaceous earth filters.
Asbestos disc filters. Sintered glass filters Membrane filters.
These filters are sterilized by autoclavingat 121c for 15 minutes.
1) Candle filters:
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1) Candle filters:USES:For purification of water.
Preparation of antibiotics, sera
Unglazed ceramic filters: after use can be cleaned with sodiumhypochlorite solution. E.g. chamber land & doulton filters.
Diatomaceous earth: This can be cleaned with hypochloritesolution E.g. Berkefeld & Mandler filters.
Advantage:
Handle large amount of contaminants
Retain particles smaller than their normal size rating because ofabsorption of particles on the filter
Disadvantages:Media migration contaminate the product.
Release of microorganisms during long process times
Retain significant amount of fluid products.
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2) Asbestos Disc filters:
are disposable, single use discs. Theyhave high adsorbing capacity
Disadvantages
Tend to alkalinize filtered liquids.
Carcinogenic potential of asbestos hasdiscouraged their use.
E.g. Seitz, carbon & sterimat filters.
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3) Sintered glass filters:
Prepared by heat fusing finely powderedglass particles of graded sizes
Low absorptive property.
Can be cleaned easily
Are brittle & expensive
4) M b filt
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4) Membrane filters:
Made up of cellulose filters or polymers used in water purification & analysis, sterilization ,sterility
testing and preparation of solutions for parenteral use. APD- 0.22 m or less size most widely used.
Advantages:
Donot contaminate the product during media migration No release of microorganisms during long process times Do not retain the fluid products.
Disadvantages:
Tend to get stopped up by excess dirt in the system.
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SONIC AND ULTRASONIC
Bactericidal
But the results are variable hence nopractical significance
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Test for efficiency:
Mechanical indicatorsthermocouplethermometers
Chemical indicators
browns tubeautoclave tape
Biological indicatorsBacillus steatothermophilus 55-60c
Bacillus subtilis 35-37cClostidium tetani 121C
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CHEMICAL METHOD
It is carried out by inserting a Browns tube insidethe hot air oven, which develop green spots at 160cafter 1 hr.
Autoclave tape contains a sensitive ink thatundergoes color change at specific temp-forms the basis of bowie-dick test for high vacuumautoclaves
TST strips
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BIOLOGICAL METHOD
Clostidium tetani on a filter paper stripand place it inside the hot air oven for
160c for 1hour . The filter paper strip isinoculated into thioglycolate media &incubated aneorobically at 37c for 5 days.
If the spores germinate it indicates hot
air oven is not working efficiently. Spores of bacillus steatothermophilus for
moist heat sterilization
RELIABILITY PARAMETERS
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RELIABILITY PARAMETERSFOR STERILIZATION
PRODUCT ASSOCIATED PARAMETERS- Bioburden- Bioresistance- Biostate- Bioshielding
- Density PROCESS ASSOCIATED PARAMETERS
- Temperature- Humidity/moisture/hydration- Time
- Purity of agent & air- Saturation/penetration- Capacity of the sterilizer & position of items within sterilizer
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CHEMICAL DISINFECTANTS
Alcohols, Aldehydes, Biguanides,Halogens, Phenolics, Quaternary
Ammonium Compounds
BACTEIOSTATIC &
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BACTEIOSTATIC &BACTERIOCIDAL AGENTS
These are the agents, which inhibit thegrowth of bacteria
These agents, which kill the bacteria.
DISIFECTANTS &
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DISIFECTANTS &ANTISEPTICS
(Patterson 1932): A chemical used on nonvital objects to kill
surface vegetative pathogenic organisms
but not necessarily spore forms or viruses. A chemical that is applied to living tissues
such as skin or mucous membrane to
reduce the number of microorganismspresent through inhibition of their activityor destruction.
HOW TO DISINFECTANTS
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HOW TO DISINFECTANTSACT?
1) Protein coagulation.
2) Disruption of cell membrane.
3) Removal of free sulphydryl groups.
4) Substrate competition.
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CHEMICAL DISINFECTANTS
Effective agent to sterilize items which are destroyedby heat.
CENTERS FOR DISEASE CONTROL ANDPREVENTION- CLASSIFICATION
- HIGH LEVEL DISINFECTANT : For killing all micro-org onsubmerged inanimate objects that are heat sensitive e.gGlutaraldehyde- INTERMEDIATE LEVEL DISINFECTANTS : For killingvegetative bacteria, most fungi, viruses and m. Tuberculosis e.g
Iodophors- LOW LEVEL DISINFECTANTS : For killing most vegetativebacteria, some fungi, and some viruses e.g quaternary ammoniumcompounds
ALCOHOLS
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ALCOHOLS
Isopropyl alcohol & 70% ethylalcohol & methyl alcohol
VIRUCIDAL ( BUT NOT LIPIDVIRUS), FUNGICIDAL,AGAINST
MYCOBACTERIUM TUBERCULOSIS
Alcohols do not solubilise proteinmaterial in blood or saliva andhence they are poor cleaners.
They dry out skin because tend todissolve fat and oil that serves asnatural skin moisteners
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ALCOHOLS
USES
EG. DETTOL- SKIN DISINFECTANTS
TIME: 10-30 MINS
Iso propyl alcohol- disinfect clinical thermometers. Lessvolatile
Ethyl alcohol- Suitable for skin preparation before
venepuncture. It is highly volatile
Methyl alcohol-to disinfect safety cabinets andincubators. Fungicidal
Aldehydes
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Aldehydes Glutaraldehyde (Cidex 2%),
&Formaldehyde (formalin 37%)
Active against G-ve bact.,
spores, viruses (HB, HIV) &fungi
Require 3 hours ofexposure
Suitable for non -autoclavable instruments
Blood/saliva spillages
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GLUTARALDEHYDE
2.4 %, 2.5%, 3.4% aqueous solution
Half life of cidex- 14 dayscidex 7- 28 days
Alkaline Glutaraldehyde changes ph rapidly and loses its
effectiveness after the date of expiration. Therefore theexpiry date has to be marked when activated
For instruments which are destroyed by heat Bactericidal, pseudomonacidal, Fungicidal and Virucidal in
10 minutes. Disinfection only ! Tuberculocidal in 45 minutes. Sporicidal in 10 hours. ( becomes a sterilant )
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GLUTARALDEHYDE
ADVANTAGES Non-corrosive Low surface tension. Not absorbed by rubber or plastics. Low volatility. Active at room temperature
DISADVANTAGES Buffer to be added for activation. Gradually loses effectiveness. May cause skin irritation. Mild odour.
Bi id
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Biguanides Chlorhexidine 2-4%- PIN CUSHION EFFECT
0.2% Active against Staph. aureus & some G-Ve bacteria
Active against fungi & viruses ONLY at very highconc
Inactivated by soap and pus Ototoxicity if instilled into the middle ear
Antiseptic: Used for disinfecting skin and mucousmembranes e.g.:
Savlon: 0.5%CHX + Cetrimide Hibiscrub: 4%CHX + detergent Hexana, Corsodyl mw =0.2% CHX
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Chlorhexidine gluconate has been shown to beeffective against all microorganisms includingStaphylococcus aureus. However, it does not have aswide a spectrum of antiviral activity as povidone-iodine. Chlorhexidine use creates a protective
bacteriostatic film on the skin that maintains a highlevel of activity against gram-positive organisms.
Chlorhexidine has been reported to causesensorineural deafness when it enters the middle ear.
There have been a few reported cases of irreversiblecorneal eye damage caused by eye contact during facialskin preparation before surgery
HALOGENS CHLORINE
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HALOGENS-CHLORINE
When mixed in water forms hypochlorousacid:Cl2 + H2O ------> H+ + Cl- + HOCl
Hypochlorousacid
Sodium hypochlorite, 10000 ppm of available
chlorine Commercial bleach 5.25% sodium hypochlorite 1:10 to 1:100 dilution
Active against bacteria, spores, fungi andviruses (HB, HIV)
20 minutes of exposure time Inactivated by blood, pus and dilution
E E
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HALOGENS-IODINE
Iodine alcohol mixtures (tinctures of iodine )
Iodine complexed with organicmaterials- iodophor
Iodophors & tinctures Active against bacteria, spores &
some viruses & fungi
Can be inactivated by pus andblood
USES Suitable for skin preparation,
mouthwash & as a surgical scrub (7.5%Povidone-iodine= Betadine)
H L GEN D NE
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HALOGEN-IODINE
Aqueous alcoholic solution can be used as skin & woundantiseptic. It is bactericidal & veridical. Strong iodine 19% weight / volume of iodine. Weak iodine solution 2% weight / volume of iodine. Betadine 12% weight / volume.- iodine sensitivity
Uses- hand washes-Preoperative skin-Preparation Sterilization of surgical instruments.
Iodoform (white head varnish) Bismuth Iodoform Paste used in dressing of
-Dry socket-cyst cavity-Bony defects.
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betadine
The most potent agents to inactivate PVP-Iinclude free sulfur-containing amino acids, suchas cysteine and methionine
Patients are typically prepared with a scrubbing
solution of 7.5% PVP-I applied in circular motionoutward from the center of the surgical site,followed with a blotting or rinse, and coveredwith a paint of a 10% PVP-I solution.
Betadine scrub contains surfactant which reducesthe surface tension and increases theantimicrobial activity
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Both gram-positive and gram-negative organisms aresensitive Povidone-iodine acts on a wide variety ofbacteria (including anaerobic and sporulatedorganisms), fungi, protozoa, and viruses. Systemictoxicity in a group of burn patients with more than 25%
of the total body surface area burned has beenreported. Refractory metabolic acidosis and acute renalfailure occurred in this group and a few died.8,9 Innewborns exposed repeatedly to povidone-iodine forskin and umbilical cord cleansing, cutaneousabsorption may lead to hypothyroidism, which may bedetrimental because thyroid hormones are critical tobrain development
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Betadine vs chlorhexidine
Iodophore
G+,G-,fungi, virus
Scrub 7.5% with surfactant
paint 10%
Irrigation 5%
iodine toxicity, hypothyroidism
in neonates
Biguanide
G+, some G- & fungi and
virus in very high
concentrations Scrub 4%
savlon 0.5% chX + cetrimide
plain 0.2%
Sensoneural deafness in middle
ear
HEAVY METALS
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HEAVY METALSInclude copper, selenium, mercury, silver, and zinc.OLIGODYNAMIC action: Very tiny amounts are effective.
MERCURY mercurochrome are used to disinfect skin wounds. mercuric chloride is strong fungicideSILVER1% silver nitrate solution is used for the treatment of dry socket
& used to relief of pain, stimulates granulamatous tissues.
COPPERCopper sulfate is used to kill algae in pools and fish tanks.Copper salts are used as fungicides.SELENIUM
Kills fungi and their spores. Used for fungal infections.Also used in dandruff shampoos.ZINCZinc chloride is used in mouthwashes.Zinc oxide is used as antifungal agent in paints.
Ph li
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Phenolics Also known as carbolic acid Joseph lister used phenol as antiseptic Synthetic phenols- intermediate level
disinfectant Hexachlorophenes Active against staph aureus, limited activity
against G-ve bacilli Uses:Surgical scrub 2% phenol (Phisomed)
House keeping disinfectant
Quaternary Ammonium Compounds
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Quaternary Ammonium Compounds
Types : Alcohol free quats (Low level
disinfectant; non tuberculocidal) Quats with alcohol ( intermediate level
disinfectant ;tuberculocidal)
Cetrimide (+0.5%CHX= Savlon) Active against staph aureus Easily inactivated by water and soap Can be contaminated by pseudomonas
B lk i hl id
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Benzalkonium chloride
It is one of the most aqueous quaternary ammoniumcompounds and is used both as an antiseptic and as adisinfectant.
According to neugeboren and co-workers its antibacterial
spectrum is similar to the alcohols being limited largely togram-positive microorganisms and some gram-negativeorganisms.
It is not effective against spores, viruses andmycobacterium tuberculosis.
Hotchkiss 1946 noted that this molecule is a strongsurfactant that increases the permeability of thebacterial well and permits the escape of phosphorus andnitrogen. It also denatures intracellular protein.
G di i f t t
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Gaseous disinfectants:
Formaldehyde
Ethylene oxide
Beta propriolactone (BPL)
FORMALDEHYDE
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FORMALDEHYDE
It is used in fumigation of operationtheatres, laboratories, to sterile books,cloths, furniture etc.
Formaldehyde not popular because of itsnoxious odors
Drawback: Since it is irritant & toxic the roomshould not opened for at least 48 hours.
ETHYLENE OXIDE
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It is a colorless liquid with boiling point 10.7c.At normal temperature and pressure, it is a gas,which have very high penetration power. It canbe used to sterilize any porous material.
12/88- 12% EO 88% CFC
10/90 10% EO 90% CO2 Temperatures- 29-63c
ADVANTAGES
Effective substitute Automatic controls preclude human errors EO leaves no film on items
ETHYLENE OXIDE
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Suitable for working surfaces & instruments It is viricidal, sporicidal & bactericidal.
14-18 hrs Drawbacks: It is highly toxic mutagenic,
carcinogenic & highly inflammable.
Limitations: The object to be disinfected must be thoroughly
cleaned Efficient at certain Concentration & Temperature Each agent needs a certain minimum exposure time Certain chemicals may damage certain surfaces
Shelf-life Complicated process requires monitoring Toxic by- products are formed Expensive
BETA PROPIOLACTONE
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BE A PROPIOLAC ONE
It has got lower penetration power. It is condensation product of ketone &
formaldehyde.
It is carcinogenic 0.2% betapropiolactone is used for
sterilization of certain vaccines. It is virucidal & bactericidal. It is used for sterilization of rabies
vaccines.
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D. Coal Tar derivatives: Phenol 5-10%
Lysol 2.5% disinfectants
Cresol 2.5-5%
Chlorhexidine antiseptics
Hexachlorophene( neurotoxic )
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E. Dyes: It is used as skin & Wound disinfectant.
High dilution-bacteriostatic & low bacteriocidal Impair DNA complexes & thus kill or destroy the
reproductive capacityIt is divided into 2 groups.Aniline dyes Eg : brilliant green, malachite green, crystal violet Active against gram +ve No activity against tubercle bacilli and hence used
in Lowenstein jensen medium Lethal effects are due to acid groups
Acridine dyes: Proflavine , acriflavine, euflavine & aminacrine
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F. Surface active agents: These are the substances which act at
energy relationship at interfaces producing areduction of surface or interfacial tension.
They are detergents, wetting agents & soaps. Soaps saturated fatty acids(coconut oil)
effective against gram ve bacilli. Soaps unsaturated fatty acids(olic acids)
effective against gram +ve bacteria.
Efficiency of various
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ff y fdisinfectants
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RECENT ADVANCES?
?
HYDROGEN PEROXIDE PLASMA STERILIZATION
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H2O2 activation Reactive plasma Plasma 4th state of matter
Produced by strong electrical andmagnetic field Plasma cloud contains ions, electrons
& neutral atomic particles that produce a pink glow
MECHANISM :Free radicals from the cloud interact with cell membranes,enzymes, nucleic acids and disrupts vital functions
They are highly sporicidal at low concentrations
Used for metallic or non metallic instruments
Oz n s st iliz ti n
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Ozone gas sterilization ozone sterilizes by oxidation that destroys
organic and inorganic matter. Penetrates membraneof cells causing them to explode. Low temperature method of sterilizationADVANTAGES :Simple and inexpensiveAlternative to gas sterilizationLeaves no residueDoes not affect ti,cr,si & teflonDISADVANTAGE :Oxidises steel, iron, brass, aluminiumDestroys natural rubber
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Test for disinfectants: It is useddetermining the quality of the disinfectant.
Rideal Walker test: Test is used to estimate the efficacy of a disinfectant.
The highest dilution of the given disinfectant that killsbacteria, divided by the highest dilution of phenol thatsterilizes the solution, within the measured time
Chick Martin Test: Modified rideal test Here the disinfectant acts in presence of
organic matter ( dried yeast of feces )
STERILIZATION OF HIVINFECTED ARTICLES
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INFECTED ARTICLES Autoclaving at 1210c ,15lbs pressure for 20 minutes. Dry heat-1600 c for 1 hour. Boiling for 20-30 minutes.CHEMICAL DISINFECTANTS Sodium hypochlorite - 5 gm/lit Calcium hypochlorite - 1.4gm/lit Chloramine - 70gm/lit Ethanol - 70% Formalin - 3-4%REUSABLE INSTRUMENTS Non autoclavable instruments should be immersed in 2%
Glutaraldehyde solution for 1 hour. The instruments are cleaned with warm water and detergent. They are rinsed left soak in 2% glutaraldehyde for 3 hours.
STERILIZATION OF HEPATITIS
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INFECTED ARTICLES
Hepatitis B virus remains viable at roomtemperature for at least 1 month
Steam autoclave 10 min exposure to 1:100 diluted bleach 1:16 diluted phenolic glutaraldehyde 75ppm iodophor 70% isopropyl alcoholHBV is easy to kill when outside the body, provided the
killing agent comes in direct contact with the virus.HBV is more easily killed than mycobacterium
tuberculosis and bacterial spores
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CONCLUSION
REFERENCES
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REFERENCES
Textbook of microbiology-Ananthanarayan
Berry & kohns operating room technique
Infection control procedures- baker Textbook of oral & maxillofacial
surgery-neelima anil malik
Art & science of operative dentistry -sturdevant
Preferred methods of sterilization for common use articles
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Autoclaving Hot air oven Ethylene oxide Glutaraladehy
de
Filtration
Animal cages Glass ware Fabric Endoscope Antibiotics
Sugar tubes Beakers Bedding Cystoscope Serum
Lab coats Flasks Blanket Vaccines
Cotton Petridish Clothing
Filters Pipette Mattresses
Instruments Slides Pillows
Culture media Syringes Disposable
instruments
RubberGloves
Stopper
Test tubesGlycerin
Needles
BladesKnives
Scalpels