sterilization deeptha

8/3/2019 Sterilization Deeptha

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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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98/100

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

sterilization deeptha

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