BIOL 209 1st Edition Lecture 21 Outline of Last Lecture I. Question/Answer’sII. DefinitionsIII. InfectionIV. Sources of DiseaseOutline of Current Lecture I. Question/Answer’sII. DefinitionsIII. Disease ProgressIV. Killing Microorganisms V. Physical ControlVI. Chemical ControlVII. AntibioticsCurrent LectureI. Question/Answer’sA. Microbial control methods that are able to kill endospores are able to sterilizeB. Why not autoclave everything we need sterilized? The temperature might affect objects negativelyC. Is washing your hands important? Yes, it gets microorganisms off, even though you are not necessarily destroying themD. Why would a microbe produce an antibiotic? To give itself an advantage to nutrients by killing off other organismsE. There are fewer antifungal and antiprotozoan drugs compared to antibacterial drugs because fungi and protozoa: are similar to human cells so that drug toxicity is a problem1. Fungi and protozoa are eukaryotic cells, like most of our cellsII. DefinitionsA. Sterilization: removal of all sources of viable microorganismsB. Disinfection: removal of vegetative pathogens – inanimate objectsC. Antisepsis: removal of vegetative pathogens – body surfaces III. Disease ProgressA. Disease progress in a population can be tracked by assessing prevalence 1. The fraction of population infected2. Disease incidence describes the rate at which new cases are appearingB. Endemic disease is present at a constant level and suggests continued exposure to a reservoirThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.C. Epidemic disease indicates a large increase in cases and suggests a new source or a change in the pathogenIV. Killing Microorganisms A. Is logarithmic and depends on time of exposure, load (amount of pathogen), type of pathogen, and type & dose of control agentB. Treatment agents can target cell wall, membranes, DNA, proteinsV. Physical ControlA. Sterilization by heat treatment1. Endospore removal is the limiting factor for sterilization and is used as a measure of effectiveness2. Moist heat is more effective than dry heata. Both act to denature proteinsb. High temperatures will eventually allow oxidation of pathogens3. Autoclaves permit high temperature steam treatment by creating a high pressure environmenta. Boiling water doesn’t get hot enough to kill everything that autoclaving wouldB. Radiation1. High energy ionizing radiation (gamma or x-ray irradiation) can sterilize by breaking DNAa. High penetration power2. Lower energy UV radiation can disinfecta. Induces pyrimidine dimers in DNA (repairable)b. Low penetration powerC. Filtration1. Removes pathogens using filters with small pore size 2. Air filtration (HEPA) high efficiency particulate air filters used in clean rooms and biologic safety cabinets3. Filtration of liquids (can be used for sterilization)VI. Chemical controlA. Typically used for disinfection or asepsis1. Alcohols target membranes2. Chlorine (bleach), Iodine, Phenolics (Lysol) – denatures proteins3. Peroxides – Hydrogen Peroxide oxidizes proteins4. Ethylene Oxide – gas sterilization through alkylation (chemical modification, including spores)VII. AntibioticsA. Produced by microbial species – usually molds (fungi) & soil bacteria1. Pharmaceutical companies often can synthesize these antibiotics and make variants with distinct