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Physical and Chemical Control Definitions • • • • • • • Sterilization Aseptic Disinfection Antiseptic Degerming Sanitation Pasteurization • • • • • Germicide Bacteriocide Bacteriostatic Fungicide Virucides Microbial Death • Death = no growth • Constant rate (log) Effectiveness of Antimicrobial Agents • Environmental Factors – Number • Concentration • Composition – – – – Organic Matter Exposure time Temperature pH • Resistance Factors Actions of Agents Alter Cell Membrane by Osmosis Alter NA • Agents – Heat – Chemical – Radiation • Results – Mutation – Stop protein synthesis Alter Proteins by Denaturing Physical Methods of Control • • • • • Temperature – Heat • Boiling • Moist/Dry • Pasteurization • Incineration – Cold • Refrigeration • Freezing Irradiation – UV – Gamma – X-rays – Microwave Filtration Drying/Desiccation Osmotic Pressure – High Salt concentrations Sterilization Methods • Heat – Boiling – Steam – Incineration • Irradiation • Filtration – Membranes • Chemical • Gas Chemical Agents • Purpose – Decrease numbers – Does not sterilize • Types – – – – Antiseptics Disinfectants Preservatives Antibiotics Antiseptics • • • • • Phenols Bisphenols Biguanines Halogens Quaterinary Ammonium Disinfectants • Types – – – – – – Phenolics Halogens Alcohol Heavy Metals Aldehydes Peroxygens • MOA – Oxidize – Denature – Disrupt membranes Degerming • Surfactants • Mechanical removal • Examples – Soaps – Detergents Food Preservatives Calcium propionate Sodium nitrate Antibiotics Resistant Organisms (most least) • Prions Endospores Mycobacteria Protozoan Cysts Vegetative protozoa Gram (-) Bacteria Fungal spores Viruses without envelopes Gram (+) Bacteria Viruses with envelopes.