بسم الله الرحمن الرحيم STERILIZATION

1. بسم الله الرحمن الرحيمSTERILIZATION Prof. Khalifa Sifaw Ghenghesh Dept. of Medical Microbiology, Faculty of Medicine, Tripoli University Tripoli - Libya

2. What is Sterilization? • The removal of all forms of living material. • Important: First Objects to Be Sterilized Should Be Cleaned by Washing.

3. 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.

6. TESTS FOR AUTOCLAVE FUNCTION • The Bowie-Dick Autoclave Tape Test: • Browne's Tubes: • Automatic Controls or Pen Records: • Bacteriological Tests (Spore Tests):

7. 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.

8. 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.

9. 5. LIQUIDES: • Disinfectants. • i. Glutaraldehyde: • a. Sterilizing Heat Sensitive Pieces of Equipments.

10. 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. _______________________________________________________________

11. 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 _______________________________________

12. PROPERTIES OF STEAM • i. Moisture content • ii. Heat content • iii. Penetration

13. 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.

14. 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.

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

16. 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:

17. "بسم الله الرحمن الرحيم"DISINFECTION AND DISINFECTANTS Prof. Khalifa Sifaw Ghenghesh Dept. of Medical Microbiology, Faculty of Medicine, Al-Fateh University Tripoli - Libya

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

19. Methods of Disinfection • A. Cleaning • Instruments with high risk organic material >> • Treat with strong disinfectant >> Cleaning >> Sterile or dispose of.

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

21. 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

22. II. Halogenic Compounds • Hypochlorites: Effective > HBV • Iodine + Alcohol Pre-operative skin antiseptic. • Bovidone Iodine: an anti-plaque agent.

23. III. Aldehydes • Formaldehyde • Gluteraldehyde • Alcohol ----------------------- Antiseptics • Are bacteriostatic agents that can be used on skin and mucosal surfaces.

24. IV. Diguanides • Chlorhexdine 0.5% + 70% alcohol >>> Skin disinfectant • Chlorhexidine gluconate Treatment of oral candidosis + oral ulceration

25. V. Quaternary Ammonium Compounds • Cetrimide VI. Organic Dyes • e.g. gentian violet

26. Factors Affecting the Effectiveness of Disinfectants: • Tests of the Proper Functioning of Liquid Disinfectants: " In-use" Tests.

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

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