Control of Microbial Growth (Sterilization and Disinfection)

1. Control of Microbial Growth(Sterilization and Disinfection)

2. Control of Microbial Growth www.petersoulsby.org www.thisoldhouse.com speedysysteminc.com askville.amazon.com www.sdada.org

3. Microbial Control • Can inhibit growth of many microorganisms by washing and scrubbing with soaps and detergents. www.enviroblog.org

4. Sterilization • Process of removing or killing all microorganisms and viruses on or in a product. • Ensures complete destruction of all microorganisms, including cells, spores, and viruses. www.kendall-ltp.com www.medicalcareerinstitute.net

5. Examples of Sterilization • Dry heat • Autoclaving • Gas • Various chemicals • Certain types of radiation Autoclave. www.lifelinemedical.net Dry Heat Sterilization. www.kabdental.com

6. Disinfection • Process that reduces # of potential disease-causing bacteria and viruses on a material until they no longer present a hazard. • Terms decontamination and sanitation mean the same thing generally. • Disinfectant • A chemical used to disinfect inanimate objects.

7. Example of Disinfection - Pasteurization • Method of disinfecting liquids. • Heat liquids to a certain temperature. • Does not totally destroy pathogens. Pasteurization Equipment. www.foodprocessing-technology.com

8. Decontamination • Inactivation or removal of both microbial toxins and the living microbial pathogens. www.foxnews.com

9. Antiseptic • Solutions used to disinfect skin and other living tissues. www.firstaid-direct.co.uk

10. Sanitation • Reduction of microbial populations to levels considered safe by public health standards. www.zerrenterprises.com

11. Microbicidal Agents • The suffix –cide or –cidal refers to “killing.” • Ex. Microbicidal agents (microbicides) • Ex. Bactericidal agents • Ex. Sporicidal agents • Ex. Viricidal agents

12. Microbistatic Agents • Microbistatic Agent • Drug or chemical that inhibits the growth and reproduction of microorganisms. • Bacteriostatic Agent • One that specifically inhibits the metabolism and reproduction of bacteria. • Microbistatic technique examples • Ex. Lyophilization (freeze-drying) • Ex. Rapid freezing (using liquid nitrogen)

13. Some Useful Terms • Sepsis • Presence of pathogens in blood or tissues. • Asepsis • Absence of pathogens. • Ex. Hand washing; use of sterile gloves, masks, gowns; sterilization of surgical equipment; use of disinfectants. • Antisepsis • Prevention of infection. • Antiseptic technique • Developed by Joseph Lister (1867). • Use of antiseptics. mateengreenway.com

14. Sterile Technique • Practice of excluding all microorganisms from a particular area, so that the area will be sterile. bioweb.wku.edu

15. Controlling Microbial Growth Using Physical Methods • Methods used to destroy or inhibit microbial growth may be physical or chemical. • Examples: • Heat • Combination of heat and pressure • Desiccation • Radiation • Sonic disruption • Filtration

16. Heat • Practical, efficient, and inexpensive method of sterilization. • 2 factors that influence effectiveness of heat for sterilization: temperature and time • Thermal Death Point (TDP) • Lowest temperature that will kill all organisms in a standardized pure culture within a specified period. • Thermal Death Time (TDT) • Length of time necessary to sterilize a pure culture at a specified temperature.

17. Dry Heat • Heating materials in absence of moisture. • Must be baked at 160º to 165ºC for 2 hours or at 170º to 180ºC for 1 hour. • Other methods include incineration and flaming surface of metal materials like forceps and loops. biology.clc.uc.edu

18. Moist Heat • Boiling or steaming. • Most pathogens destroyed after 30 minutes of boiling. • Boiling not always effective against some endospores and viruses. • Boiling not an option for thermophiles. Boiling. ttt.astro.su.se Steamer. www.appliancist.com

19. Autoclaving • Large metal pressure cooker that uses steam under pressure to completely destroy all microorganisms. • Increased pressure raises the temperature of boiling water (i.e. above 100ºC) producing steam. www.uwm.edu

20. Home Canning • Use of a pressure cooker. • If foods canned without pressure some bacterial endospores may survive. • i.e. Clostridium botulinum www.thecookwarebarn.com Bulging lid – botulism. calorielab.com

21. Disinfecting Techniques • For clothing, bedding, and dishes • Use hot water with soap or detergent • Agitate solution around items • Combination of heat, mechanical action, and chemical inhibition kills most microbes. Washing Machine. www.genexe.com

22. Cold • Metabolic activities slowed. • Most microbes not killed, but growth inhibited. • Slow freezing not a good way to preserve bacteriological or biologic specimen. • Rapid freezing (liquid nitrogen) good for this. • Why should you not refreeze foods? www.themodernapprentice.com Slow Freezing. Rapid Freezing – liquid nitrogen. encarta.msn.com

23. Desiccation • Process of drying materials. • Many microbes can remain viable despite absence of nutrients and moisture. • Ex. Lyophilization (freeze-drying) • Dried blood, fecal material, and dust may still contain viable microbes. www.mahalo.com

24. Radiation • Ultraviolet (UV) light sometimes used to prevent or decrease microbial growth. • X-rays and gamma and beta rays may be used to destroy or prevent microbial growth. www.moondragon.org www.fda.gov

25. Ultrasonic Waves • Often used to sterilize and clean delicate equipment. • Consists of tanks filled with liquid solvent (usually water). • Short sound waves are passed through liquid. • Sound waves dislodge organic debris. • Materials must then be washed and sterilized by another method.

26. Filtration • Filters of various pore sizes are used to filter or separate larger cells, larger viruses, bacteria, and other microbes from gases or liquids in which they are suspended. • Paper masks used to prevent the outward and inward movement of microbes. wps.prenhall.com health.howstuffworks.com

27. Gaseous Atmosphere • Altering atmosphere of microbes to inhibit growth. Gas gangrene – caused by Clostridium spp. www.humanillnesses.com Hyperbaric Chamber. www.perlhealth.com

28. Chemical Agents Used to Inhibit Microbial Growth • Temporarily or permanently. • Different disinfectants have different properties. • Disinfectants should be chosen based on their efficiency and effectiveness for a particular situation.

29. What Are Some Things to Consider When Choosing a Chemical Disinfectant?

30. What makes an Ideal Chemical Antimicrobial Agent?

31. How Do Disinfectants Kill Microorganisms? • Some target and destroy cell membranes. • Ex. Surface-active soaps and detergents; alcohols • Some destroy enzymes and structural proteins. • Ex. Formaldehyde and ethylene oxide • Some attack cell walls or nucleic acids.

32. Antiseptics • Can be used safely on human skin. • Reduces # of organisms on the surface. • Does not penetrate pores or hair follicles. www.superstock.com

33. Preventing Growth of Pathogens in Our Kitchens www.homesteadwoodworks.ca

34. The Antibiotic Controversy www.smh.com.au www.ferret.com.au

35. The End