STERILIZATION AND DISINFECTION CHAPTER 12

Terminology Disinfection- reduction of number Disinfectant used on inanimate objects (most do not kill spores) Antiseptic can be used on skin Sterilization (Autoclave) 20 mins at 121 degrees and 18 PSI

Chemical Antimicrobials Potency Phenol coefficient Filter paper method Use dilution test mic: minimum inhibitory conc

Microbial Sidebar 27-2

Disinfectant Selection Criteria Time of action Safety Microbe range Penetration Preparation Cost Odor

Mechanisms of Action Protein damage

Mechanisms of Action Membrane damage Other

Disinfectant Types Soaps/detergents Acids/Alkalis Heavy Metals Halogens Such as mercury Such as iodine, bromine and chlorine

Disinfectants (cont.) Alcohols Phenolics Oxidizers Alkylating agents Dyes Peroxides

Alkylating agents Ethylene oxide

Physical Antimicrobial Agents Heat Application Dry Heat Moist Heat Pasteurization 171 deg, 1 hr 62.9 for 30 mins

The Autoclave

Survival fraction (log scale) Fig. 27-1 Decimal reduction time (D) 100 50°C 10 Survival fraction (log scale) 70°C 60°C 1 0.1 10 20 30 40 50 Time (min)

Fig. 27-3 Chamber pressure gauge Steam exhaust Steam exhaust valve Door Jacket chamber Thermometer and valve Air exits through vent Steam supply valve Steam enters here Autoclave time 130 Stop steam 120 Temperature (°C) Begin pressure Sterilization time 110 Flowing steam Temperature of object being sterilized Temperature of autoclave 100 10 20 30 40 50 60 Total cycle time (min)

Physical Antimicrobial Methods Refrigeration/Freezing Dessication Freeze-drying

Physical Antimicrobial Methods Radiation Filtration 0.45 micron

Fig. 27-4

Physical Antimicrobial Methods Osmotic Control Sugar or salt