Micro ch. 7 Free response
Table 7.5 The following results were obtained from a use-dilution test of two disinfectants. Cultures were inoculated into tubes containing varying concentrations of the disinfectants, incubated for 10 min. at 20C, and then transferred to growth media without disinfectant. (+ = growth; = no growth) In Table 7.5, which disinfectant is most effective? Against which group of bacteria is Disinfectant A most effective?
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The results below were obtained from a use-dilution test of two disinfectants. Cultures were inoculated into tubes with varying concentrations of disinfectants and incubated for 24 hr at 20C, then subcultured in nutrient media without disinfectants. (+ = growth; = no growth) In Table 7.4, what is the minimal bacteriostatic concentration of each disinfectant? Which compound is bactericidal? At what concentration?
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Assume that you are responsible for decontaminating materials in a large hospital. How would you sterilize each of the following? Briefly justify your answers. a. a mattress used by a patient with bubonic plague b. intravenous glucose-saline solutions c. used disposable syringes d. tissues taken from patients
A) hepa vacuuming, ultraviolet germicidal radiation, light enzyme most to kill remaining colonies. B) Put it in the autoclave C)it's disposable one time use so just throw it away. Use ethylene oxide if u must sterilize them first(which seems a bit unnecessary considering they have special bins for bio waste D) Gamma irradiation and gas sterilization with ethylene oxide can be used to sterilize human tissue taken from patients. the gas penetrates the tissue.
List the microbial targets of disinfecting chemicals and provide one example of a chemical agent that affects that structure.
Four main categories of cellular targets for chemical agents. - Cell wall. - Cell membrane. - Cellular synthesis processes (DNA, RNA). - Proteins. Any dehydrating agents like alchohal will affect bacteria structure
How is hydrogen peroxide antimicrobial?
Kills spores and all other microbes; works by oxygen forming free radicals that are highly toxic and reactive to cells.
Why must most milk sold in the U.S. be refrigerated at all times while evaporated canned milk and milk in cardboard containers sold in Europe do not need to be refrigerated until they are opened?
Refrigeration slows down the growth of spoilage bacteria and ensures that the product stays fresher longer but does not kill all bacteria. In europe, all bacteria in their packaged milk are killed until the milk is opened.
What are the advantages of gluteraldehyde compared to formaldehyde?
gluteraldehyde is less pungent and less irritating. Glut is an effective cold sterilizing agent. Formaldehyde is a tissue fixative.
