1. 1 STERILIZATION AND DISINFECTION CHAPTER 7

2. 2 Terminology Disinfection: Reducing the number of pathogenic microorganism in or on an object so that they pose no threat of disease –Disinfectant: Applied to inanimate object –Antiseptic: Applied to living tissue Sterilization: Killing or removing all microorganism in or on an object

3. 3 Chemical Antimicrobials - Potency

4. The Filter Method Staphylococcus aureus (G+) Escherichia coli (G-)

5. 5 Disinfectant Selection Criteria Time of action –Fast acting Safety –Without destroying tissue Microbe range –Broad Penetration –Withot damage or discolor the material Preparation –Easy and stable with light, heat etc Cost –Inexpensive Odor –No unpleasant odor

6. 6 Mechanisms of Action Protein denaturation and degradation

7. 7 Mechanisms of Action Membrane damage

8. 8 Disinfectant Types Soaps/detergents Alcohols Quats Acids/Alkalis Phenols Heavy Metals Oxidizing Agents Halogens Ethylene Oxide Dyes Salt

9. 9 Disinfectants (cont.) Hydrogen peroxide disinfection Vaporized H 2 O 2 sterilizes small, sealable spaces such as hood and transfer room. Not enough for operating rooms

10. Ethylene oxide chamber It is explosive and carcinogenic.

11. 11 Physical Antimicrobial Agents Heat Application –Dry Heat: Oven or open flame 171°C for 1 hour 160 °C for 2 hours 121 °C for 16 hours –Moist Heat: Autoclav 121 °C, 15bl/in 2 for 15 to 20 minutes until the indicator shows change –Pasteurization – Salmonella & Mycobacterium in Milk and Beer 71.6°C for 15 minutes 62.9°C for 30 minutes

15. 15 The Autoclave

18. 18 Physical Antimicrobial Methods Refrigeration/Freezing Dessication Freeze-drying

19. 19 Physical Antimicrobial Methods Drying

21. 21 Physical Antimicrobial Methods Radiation

22. Filtration Physical Antimicrobial Methods