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67 Cards in this Set
- Front
- Back
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What is sterilization?
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Destruction of all viable organisms
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What is disinfection?
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The killing OR inhibition of ogranisms on inanimate objects
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What is sanitization?
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Reduction of microbials to a level that is deemed safe
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What is antiseptics?
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A chemical agent that kills or inhibits growth on living tissue
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What is chemotherapy?
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Use of chemicals to kill or inhibit growth WITHIN host tissue
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Term for killer?
Term for inhibitor? |
Cidal agents
Static agents |
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A germicid can kill a pathogens and non-pathogens, but NOT necessarily ______.
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endospores
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What are examples of germicides? (killers)
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bactericides
fungicides viricides |
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Are microorganisms killed instantly?
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No
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Population death usually occurs ______.
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exponentially
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How do we measure the efficiency of a killing agent?
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1. The time it takes to kill off at least 90%
2. All "viable, but not culturables" must be dead |
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Name six "conditions" that influence an antimicrobials effectivness
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1. Population size
2. Population composition 3. Concentration of agent 4. Duration of exposure 5. Temperature 6. Local environment |
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How does population size influence the effectivness?
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Larger populations take longer to kill
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How do population composition influence the effectivness?
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Different organisms have different sensitivity to a particular agent
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How does the concentration of the agent influence effectivness?
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Higher concentrations kill more rapidly
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How does the duration of exposure influence effectivness?
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The longer the exposure, the more that are killed
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How does temperature influence effectivness?
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Higher temps usually increase killing
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Give some example of how the "local environment" can influence effectivness.
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1. Organisms with biofilms will be less susceptible
2. pH levels |
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Name the three "physical" control methods.
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1. Heat
2. Filtration 3. Radiation |
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Name the four "heat" methods to control bacteria
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1. Moist heat
2. Steam sterilization 3. Pasterurization 4. Dry Heat sterilization/incineration |
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List characteristics of "moist heat" control
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1. Destroys viruses, fungi and bacteria
2. Boiling does not destroy endospores 3. Degrades and denatures nucleic acids |
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List characteristics of "steam sterilization" control
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1. Must be above 100 degrees C
2. Autoclave is used 3. Effective against spores! |
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List characteristics of "pasteurization" control
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1. Controlled heating well BELOW boiling
2. Used for milk, beer, etc 3. Does not sterilize, but reduces total load of organisms |
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List characteristics of "dry heat sterilization" control
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1. Least effective
2. Requires higher temp and longer exposure 3. Oxidizes cell and denatures it |
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What is a great example of dry heat incineration?
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Those heat-burner things we use in lab to burn our loops before innoculating
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Why would we use "filtration" as a means of control?
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For heat-sensitive materials
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What do we use "filtration" control for?
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1. To reduce microbial population
2. To reduce populations in the air |
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How do we "filter" liquids?
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Through membrane filters (physical filters that remove microorgansims)
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How do we filter organisms within the air?
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1. Surgical masks
2. Cotton plugs 3. HEPA filters |
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How do we use "radiation" as a control?
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1. 260 wavelength is usally lethal to all bacteria
2. UV is limited: does not penetrate glass, dirt, water, etc 3. |
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What type of "radiation" control DOES penetrate deep into objects?
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Ionized (gamma) radiation
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What are the three "chemical" control agents?
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1. Disinfection
2. Antisepsis 3. Sterilization |
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List 3 characteristics of chemical agent controls
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1. Must be effective against wide variety of organisms at LOW concentrations
2. Effective in the presence of organic matter 3. Overuse can create resistance |
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List characteristics of "phenolics" - a chemical control
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1. Used in labs and hospials
2. Denatures proteins in cells 3. Can cause skin irritation |
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List characteristics of "alcohols" - a chemical control
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1. Most widely used
2. Most common: ethanol and isoproanol 3. Can't kill spores |
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What are halogens and name 5 of them.
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Antimicrobial agens lethal to oganisms
Iodine, Chlorine, Bromine, Flurine, Astatine |
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What is significant about the halogen iodine
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It can kill spores at high concentrations
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What is significant about the halogen chlorine?
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1. Disenfects water
2. Chlorine gas is sporicidal |
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What is significant about "aldehydes" - a chemical control?
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1. Sporicidal
2. Inactivates nucleic acids and proteins |
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Why do we use sterilizing gases?
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1. For heat-sensitive materials
2. Sporicidal |
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How are antimicrobial agent's effectvness evaluated?
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1. By US federal agencies
2. FDA 3. Phenol Coefficient Test 4. Use dilution testing |
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What is another way to control bacteria other than "physical" and "chemical"?
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Biological control
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In general, what is biological control?
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1. Emerging field showing great promise
2. Predation - using one organism to kill another |
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What are chemotherapeutic agents?
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1. Chemicals used to treat disease
2. Destroys microbes 3. Most are antibiotics |
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Regarding antimicrobial drugs, what is the difference between therapeutic dose and toxic dose?
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Therapeutic - dose required for clinical treatment
Toxic - level at which drug is too toxic for patient (sideffects occur) |
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What is a narrow-spectrum drug? Broad-spectrum drug?
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Narrow: attacks only specific pathogens
Broad: attacks many pathogens |
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What are the two ways in which antimicrobial drugs are EXPRESSED?
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1. Minimal inhibitory concentration
2. Minimal lethal concentration |
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What are the 3 ways we can determine antimicrobial activity?
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1. Dilution tests
2. Kirby Bauer disk diffusions (from lab) 3. E-test |
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What are disk diffusion tests?
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We did these in lab (observed "clear" zones)
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What is the E Test?
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Similar to disk diffusion, but uses strips rather than disks.
Strip contains gradient of an antibiotic (fig 34.4 slide) |
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What are the 4 antimicrobial "modes of action"? In other words, how they effect cells?
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1. Inhibitors of cell wall synthesis
2. Protein synthesis inhibitors 3. Metabolic antagonists 4. Nucleic acid inhibition |
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Give two examples of a cell wall inhibitor
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1. Penicillins
2. Cephalosporins (used for people whom are allergic to penicillins |
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Why are there so few effective antifungal drugs?
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Because eukaryotic fungal cells and human cells are very similar
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What are some factors that influence whether antimicrobial drugs will be effective?
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1. Can it reach it's intended destination
2. Concentration w/out being toxic |
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Drug resistance: once it originates, resistance is not easily transmitted to other bacteria. T or F?
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False
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Resistance mutants arise ______.
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spontaneously
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What is a very serious threat to human health?
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Drug resistant organisms
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What are ways in which an organism "resists" a drug?
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1. Prevents entrance to cell
2. If entered, can pump it out 3. Inactivates the drug 4. Uses alternate metabolic pathways |
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How is resistance transmitted from bacteria to other bacteria?
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1. Immunity genes
2. Horizontal gene transfer 3. Resistance plasmids |
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What is D Value?
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The time required to kill 90 percent of the organism
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What is the D Value period for "sterilization"
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7 log Deaths
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What are the 5 types of "temperature" control methods?
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1. Dry Heat
2, Moist Heat 3. Fractional Sterilization 4. Pateruization 5. Low Temp |
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What are the other 4 types of control methods?
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1. Dessication - used to preserve food
2. Radiaiton 3. Filtration - HEPA, depth and membrane filters 4. Osmotic pressure |
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List 4 "ideal" characteristics of an antimicrobial chemical agent
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1. Capacity to penetrate
2. Inexpensive 3. Soluable in water 4. Selective toxicity |
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What are the 11 "groups" of chemical agents?
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acids, bases, phenols, alcohols, halogens, heavy metals, aklylating agents, oxidizing agents, dyes, detergents, ammonium compounds
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MIC?
MBC? |
Miniumun Inhibitory Concentration
Miniumun Bacteriocidal Concentration |
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Name several properties of an "ideal" chemotherapeutic agent
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1. Nontoxic to host
2. Shows activity in low concentrations 3. Leaves host defenses unaltered 4. Remains stable |
