بسم الله الرحمن الرحيم STERILIZATION

الرحيم الرحمن الله بسم

STERILIZATION

Prof. Khalifa Sifaw GhengheshDept. of Medical Microbiology,

Faculty of Medicine, Tripoli UniversityTripoli - Libya

What is SterilizationWhat is Sterilization??

• The removal of all forms of living material.

• Important: First Objects to Be Sterilized Should Be Cleaned by Washing.

METHODS OF STERILIZATION

1. DRY HEAT– Red Heat– Hot - Air Oven: • 160o/ 60 minutes• 180o/ 20 minutes

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

On 3 Consecutive Days.– The Autoclave: > Pressurized Steam.• 121oC/ 1.1 bar for 15 minutes.• 134oC/ 2.2 bar for 3 minutes.

• TESTS FOR AUTOCLAVE FUNCTION

–The Bowie-Dick Autoclave Tape Test:–Browne's Tubes:–Automatic Controls or Pen Records:–Bacteriological Tests (Spore Tests):

• 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.

• 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.

• 5. LIQUIDES: –Disinfectants.

• i. Glutaraldehyde:– a. Sterilizing Heat Sensitive Pieces

of Equipments.

Forms of Sterilization by Heat and Principle Uses._______________________________________________________________

Type of Heat Use_______________________________________________________________

DRY:1. Red Heat. Microbiological Loops. Incineration of

UsedLab. Culture Plates.

2. Hot - Air Oven. Many Surgical & Dental Instruments but Not Fabrics or Rubber.

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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. _______________________________________________________________

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

_______________________________________

• PROPERTIES OF STEAM

–i. Moisture content

–ii. Heat content

–iii. Penetration

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.

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.

3. Unwrapped Instrument and Utensil

Sterilizers:• DSL autoclaves

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

• 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:

" الرحيم الرحمن الله "بسم DISINFECTION AND DISINFECTANTS

Prof. Khalifa Sifaw GhengheshDept. of Medical Microbiology,

Faculty of Medicine, Al-Fateh University

Tripoli - Libya

DisinfectionDisinfection

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

Methods of DisinfectionMethods of Disinfection

• A. Cleaning• Instruments with high risk organic

material >>

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

B. Disinfection by Heati. Pasteurizationii. Boiling wateriii. Flaming off alcohol

C. Physical Methods• UltrasonicsUltrasonic vibration >

Disrupte microorganismse.g. Ultrasonic scalers.

D. Chemical DisinfectantsDenaturing protein or lipidAct: Disrupting the biosynthetic pathways

I. Phenols• Clear phenolic solutions:

• Black and White Phenolic Compounds:

• Chloroxylenol: (Dettol)

• Hexachlorophane: Pre-operative scrub

II. Halogenic Compounds

• Hypochlorites: Effective > HBV

• Iodine + Alcohol

Pre-operative skin antiseptic.

• Bovidone Iodine:

an anti-plaque agent.

III. Aldehydes• Formaldehyde• Gluteraldehyde• Alcohol

-----------------------

Antiseptics• Are bacteriostatic agents that can

be used on skin and mucosal surfaces.

IV. Diguanides• Chlorhexdine

0.5% + 70% alcohol >>> Skin

disinfectant

• Chlorhexidine gluconate Treatment of oral candidosis + oral

ulceration

V. Quaternary Ammonium Compounds

• Cetrimide

VI. Organic Dyes• e.g. gentian violet

• Factors Affecting the Effectiveness of Disinfectants:

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

Storage of Sterile Instruments• Never store instruments in liquid

disinfectants.

Waste Disposal

Special Problems• HBV, HCV and HIV (AIDS)

Sterilization and Disinfection

in Dentistry

• Sterilization >>> Autoclave.

• Dental instruments can and should be

autoclaved after each patient.

• Nozzles of air and water spray: ??