STERILIZATION-DISINFECTION and DISINFECTANTS.ppt

8/10/2019 STERILIZATION-DISINFECTION and DISINFECTANTS.ppt

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STERILIZATION

Prof . K h al i fa Sifaw Gheng h es h

Dept. of Medical Microbiology,Faculty of Medicine, Tripoli UniversityTripoli - Libya


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What is Sterilization?

The removal of all forms of living

material.

Important: First Objects to BeSterilized Should Be Cleaned byWashing.


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METHODS OF STERILIZATION

1. DRY HEAT Red Heat Hot - Air Oven:

160o

/ 60 minutes 180 o / 20 minutes

2. MOIST HEAT: Tyndallization: > 100 oC/ 30 minutes

On 3 Consecutive Days. The Autoclave: > Pressurized Steam.

121 oC/ 1.1 bar for 15 minutes. 134 oC/ 2.2 bar for 3 minutes.


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TESTS FOR AUTOCLAVE FUNCTION

The Bowie-Dick Autoclave Tape Test: Browne's Tubes: Automatic Controls or Pen Records:

Bacteriological Tests (Spore Tests):


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2. IRRADIATION i. Ultra - Violet Radiation (UV):

a. Not Recommended. b. Poor penetration in Air. c. Suitable to Reduce Microbial Counts

in Safety Cabinets.

ii. Gamma - Ray Radiation

Source: Cobalt 60. a. Lethal to All Forms of Microbial

Life. b. Used Commercially.


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3. FILTRATION

Bacterial Stopping Filters.

4. GASES

i. Ethylene Oxide Gas: a. Ventilators. b. Toxic & Explodes When Mixed

with Air . ii. Formaldehyde:

a. Rooms and Lab. Cabinets.


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5. LIQUIDES: Disinfectants.

i. Glutaraldehyde: a. Sterilizing Heat Sensitive Pieces

of Equipments.


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Forms of Sterilization by Heat and Principle Uses.

_______________________________________________________________Type of Heat Use

_______________________________________________________________DRY:1. Red Heat. Microbiological Loops. Incineration of Used

Lab. Culture Plates.2. Hot - Air Oven. Many Surgical & Dental Instruments but Not

Fabrics or Rubber.----------------------------------------------------------------------------------------------------------MOIST:1. Steam at 100 oC Some Bacteriological Media.On 3 Consecutive Days.

2. Pressurized Most Surgical and Dental Instruments,Steam (Autoclave). Fabrics & Dressings (If Wrapped); Most

Microbiological Media & Glassware. _______________________________________________________________


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Heat Content of Water and Steam_______________________________________

Phase Temp. Heat Content (kJ/kg)of oC Sensible Latent TotalWater Heat Heat Heat

-----------------------------------------------------------------Liquid 100 419 0 419Vapour 100 419 2257 2676Vapour 121 509 2199 2708Vapour 135 567 2160 2727

_______________________________________


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PROPERTIES OF STEAM

i. Moisture content

ii. Heat content iii. Penetration


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PRESSURE STEAM STERILIZERS

1. Porous Load Sterilizers (Prevacuum type): Removal of air and heating of the chamber. Sterilization of the load. Removal of steam and drying of the load by

mechanical evacuation. Admission of filtered air to restoration

atmospheric pressure.


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2. Downward Displacement Jacketed

Sterilizers: Gradual displacement of air by incoming

steam while the chamber is heated to theselected sterilizing temp.

Sterilization of the textile packs for30 min/ 121oc.

Drying of the load by partial vacuum. Restoration of the chamber to

atmospheric pressure.


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3. Unwrapped Instrument and UtensilSterilizers:

DSL autoclaves

4. Fluid Sterilizers: e.g. water, iv solutions, etc.


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Factors influencing sterilizationtime for fluids: rate of heating of the chamber:

type of container: viscosity of the liquid: volume of the liquid: trapped air:


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" "DISINFECTION AND DISINFECTANTS

Prof . K h al i fa Sifaw Gh en g h eshDept. of Medical Microbiology,

Faculty of Medicine, Al-Fateh UniversityTripoli - Libya


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Disinfection

The removal of most of the

pathogenic microorganism, butoften non-pathogenic or resistantforms of pathogens remain .


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Methods of Disinfection

A. Cleaning Instruments with high risk organic

material >>

Treat with strong disinfectant >>Cleaning >> Sterile or dispose of.


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B. Disinfection by Heati. Pasteurization

ii. Boiling wateriii. Flaming off alcohol

C. Physical Methods UltrasonicsUltrasonic vibration >

Disrupte microorganisms

e.g. Ultrasonic scalers.


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D. Chemical DisinfectantsDenaturing protein or lipid Act: Disrupting the biosynthetic pathways

I. Phenols Clear phenolic solutions: Black and White Phenolic Compounds: Chloroxylenol: (Dettol) Hexachlorophane: Pre-operative scrub


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II. Halogenic Compounds

Hypochlorites: Effective > HBV Iodine + Alcohol

Pre-operative skin antiseptic.

Bovidone Iodine:an anti-plaque agent.


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III. Aldehydes Formaldehyde Gluteraldehyde Alcohol

-----------------------Antiseptics

Are bacteriostatic agents that canbe used on skin and mucosalsurfaces.


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IV. Diguanides Chlorhexdine

0.5% + 70% alcohol >>> Skindisinfectant

Chlorhexidine gluconate

Treatment of oral candidosis + oralulceration


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V. Quaternary Ammonium Compounds Cetrimide

VI. Organic Dyes e.g. gentian violet


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Factors Affecting the Effectiveness

of Disinfectants:

Tests of the Proper Functioning ofLiquid Disinfectants:" In-use" Tests.


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Storage of Sterile Instruments

Never store instruments in liquiddisinfectants.

Waste Disposal

Special Problems HBV, HCV and HIV (AIDS)


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Sterilization and Disinfectionin Dentistry

Sterilization >>> Autoclave. Dental instruments can and should be

autoclaved after each patient. Nozzles of air and water spray: ??

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STERILIZATION-DISINFECTION and DISINFECTANTS.ppt