??? ???? ?????? ?????? STERILIZATION

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??? ???? ?????? ?????? STERILIZATION

• Prof. Khalifa Sifaw Ghenghesh
• Dept. of Medical Microbiology,
• Faculty of Medicine, Tripoli University
• Tripoli - Libya

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What is Sterilization?

• The removal of all forms of living material.
• Important First Objects to Be Sterilized Should
  Be Cleaned by Washing.

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METHODS OF STERILIZATION

• 1. DRY HEAT
• Red Heat
• Hot - Air Oven
• 160o/ 60 minutes
• 180o/ 20 minutes
• 2. MOIST HEAT
• Tyndallization gt 100oC/ 30 minutes On 3
  Consecutive Days.
• The Autoclave gt Pressurized Steam.
• 121oC/ 1.1 bar for 15 minutes.
• 134oC/ 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 100oC 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 Total
• Water Heat Heat Heat
• --------------------------------------------------
  ---------------
• Liquid 100 419 0 419
• Vapour 100 419 2257 2676
• Vapour 121 509 2199 2708
• Vapour 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 the selected
  sterilizing temp.
• Sterilization of the textile packs for
• 30 min/ 121oc.
• Drying of the load by partial vacuum.
• Restoration of the chamber to
• atmospheric pressure.

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• 3. Unwrapped Instrument and Utensil
• Sterilizers
• DSL autoclaves
• 4. Fluid Sterilizers
• e.g. water, iv solutions, etc.

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• Factors influencing sterilization time 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. Khalifa Sifaw Ghenghesh
• Dept. of Medical Microbiology,
• Faculty of Medicine, Al-Fateh University
• Tripoli - Libya

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Disinfection

• The removal of most of the pathogenic
  microorganism, but often non-pathogenic or
  resistant forms of pathogens remain.

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Methods of Disinfection

• A. Cleaning
• Instruments with high risk organic material gtgt
• Treat with strong disinfectant gtgt Cleaning gtgt
  Sterile or dispose of.

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• B. Disinfection by Heat
• i. Pasteurization
• ii. Boiling water
• iii. Flaming off alcohol
• C. Physical Methods
• Ultrasonics
• Ultrasonic vibration gt
• Disrupte microorganisms
• e.g. Ultrasonic scalers.

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• D. Chemical Disinfectants
• Denaturing 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 gt 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 can be used on
  skin and mucosal surfaces.

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• IV. Diguanides
• Chlorhexdine
• 0.5 70 alcohol gtgtgt Skin
• 
  disinfectant
• Chlorhexidine gluconate
• Treatment of oral candidosis oral
• 
  ulceration

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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 of Liquid
  Disinfectants
• " In-use" Tests.

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• Storage of Sterile Instruments
• Never store instruments in liquid disinfectants.
• Waste Disposal
• Special Problems
• HBV, HCV and HIV (AIDS)

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• Sterilization and Disinfection
• in Dentistry
• Sterilization gtgtgt Autoclave.
• Dental instruments can and should be
• autoclaved after each patient.
• Nozzles of air and water spray ??