Lecture 21Outline of Last Lecture1. Radiation2. Filtration3. Qualities of ChemicalsOutline of Current Lecture 1. Levels of Chemical Decontamination2. Detergents & Soaps3. Treatment & Prevention of DiseaseCurrent LectureLevels of Chemical Decontamination- High-level germicides- Devices that are not heat sterilizable and intended to be used in sterile environments (body tissue) *Could be sterilants - Intermediate-level- Used to disinfect devices that will come in contact with mucous membranes but are not invasive- Low –level- Clean surfaces that touch skin but not mucous membranes. Eliminate only vegetative cells only.Factors that Affect Germicidal Activity of Chemicals- Nature of material being treated- Degree of contamination- Time of exposure- Strength and chemical action of germicideDetergents & Soaps- Disrupt growth of microbes- All things that are surfactants and impacts membrane of bacteria and fungi- Soaps- mechanistic action, mechanical removal of microbes- Dilution test: Take different concentrations, dip cylinder, expose cylinder to disinfectant, put cylinder in contact with media designed to neutralize. Go back and measure growth. o Requires cylinder completely immersed in chemical usedo MIC- Minimum inhibitory concentrationKirby-Bauer- In lab (press down with 5 white circles): Can see zone of inhibition- E-Test Gradient- Strip, instead of dots. Strip has changing concentration of whatever agent BSC 160 1nd EditionChapter 17- Treatment & Prevention of Disease (17.5-17.6)Antimicrobial compounds-- Prophylaxis- Preventing disease, pregnancy- Combined therapy- Taking protocol using 2+ drugs to help with treatment of infection- Drug synergy- 2 drugs working together have greater impact than drugs by themselvesAntimicrobial compounds- Antibiotics- Antibiotic- Low molecular weight compound by 1 organic organism that inhibits growth of another- Synthetic – Man-made, synthesized in lab, chemotherapeutic agents- Semisynthetic- Made modifications to synthetic to make it slightly more effective- Selective Toxicity- Does mostly harm to organism you’re trying to treat. Toxicity needs to be aimed at organism Need to know about Prokaryotes & Eukaryotes- Spectrum- Broad: work on wide range of organisms Narrow: work on subset of organismsAntimicrobial compound properties- Need to be selectively toxic- Wide spectrum- Non-allergenic - Permeable - Inexpensive to produce- Chemically stable - Difficult for microbe to develop resistance Helms thinks we should add…- Want to be microbial-cidal and not microbial static- Going to complement or enhance host system2/3 of 9000 natural antibiotics have come from
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