1/17/2016 Principles of Effective Disinfection Factors that Affect Germicidal Activity of 。 Read the label-tells you what organisms the Chemicals disinfectant is effective against and at what concentration to use it for greatest effect Nature of the material being treated Organic matter may interfere with action of the disinfectant Degree of contamination Desirable qualities of chemicals: ·Time of exposure rapid action in low concentration solubility in water or alcohol and stable in Strength and chemical action of the solution germicide broad spectrum with low toxicity penetrating noncorrosive and non-staining af fordable and readily available Levels of Chemical Decontamination Evaluating a Disinfectant High-level-kills endospores:may be sterilants Use-dilution tests devices that are not sterilized by heat and Current standard by the American Official Analytical intended to be used in sterile environments(body Chemist tissue) 1.Metal or glass cylinders are dipped in standardized Intermediate-level-kills fungal spores(not bacterial liquid cultures,Salmonella choleraesuis, endospores),tubercle bacillus,and viruses Staphylococcus aureus,and Pseudomonas aeruginosa used to disinfect devices that will come in contac 2.The cylinders are dried at 37eC for a short time. with mucous membranes but are not invasive Low-level-eliminates only vegetative bacteria, vegetative fungal cells,and some viruses 4.Rings are transferred to culture media to determine whether ba teria survived treatment. clean surfaces that touch skin but not mucous 5.Effectivene membranes eby the e of 11 1/17/2016 11 Principles of Effective Disinfection • Read the label - tells you what organisms the disinfectant is effective against and at what concentration to use it for greatest effect • Organic matter may interfere with action of the disinfectant • Desirable qualities of chemicals: rapid action in low concentration solubility in water or alcohol and stable in solution broad spectrum with low toxicity penetrating noncorrosive and non-staining affordable and readily available Factors that Affect Germicidal Activity of Chemicals • Nature of the material bein g treated • Degree of contamination • Time of exposure • Strength and chemical action of the germicide Levels of Chemical Decontamination High-level – kills endospores; may be sterilants devices that are not sterilized by heat and intended to be used in sterile environments (body tissue) Intermediate-level – kills fungal spores (not endospores), tubercle bacillus, and viruses used to disinfect devices that will come in contact with mucous membranes but are not invasive Low-level – eliminates only vegetative bacteria, vegetative fungal cells, and some viruses clean surfaces that touch skin but not mucous membranes Evaluating a Disinfectant Use-dilution tests Current standard by the American Official Analytical Chemist 1. Metal or glass cylinders are dipped in standardized bacterial liquid cultures. Salmonella choleraesuis, Staphylococcus aureus, and Pseudomonas aeruginosa 2. The cylinders are dried at 37oC for a short time. 3. Dried cultures are placed in disinfectant at the manufacturer’s recommendation for 10 min at 20oC. 4. Rings are transferred to culture media to determine whether bacteria survived treatment. 5. Effectiveness is determined by the number of cultures that grow