Unit 4 Exam Flashcards Answers
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Unlock answersPhysical Method: Moist Heat Types and What it Does |
Boiling, Autoclaving, Pastuerization, and Ultrahigh-Temp. sterilization
Denatures proteins and destroys membranes |
Physical Method: Dry Heat Types and Actions |
Hot Air - Denatures Proteins and Incineration - oxidizes everything
Denatures protiens, destroys membranes, oxidizes metabolic compounds |
Physical Method: Non-Heat Methods Types and Attributions |
Refrigeration Freezing Desiccation Lyophilization
Inhibits Metabolism |
| Physical Methods: Filtration |
| Physical separates microbes from air and liquids |
| Physical Methods: Osmotic Pressure |
| Inhibits metabolism thru the exposure to hypertonic solutions |
Physical Methods: Ionizing Radiation VS Non-Ionizing Radiation
|
Destroys DNA thru extended exposure to radiation
VS
Ultra-Violet light - have the formation of thymindimers - inhibits DNA transcription and replication |
| Chemical Methods: Phenol (Carbolic Acid), Phenolics, and Alcohols |
Denatures proteins and disrupts cell membranes Disinfects and antiseptics |
| Chemical Methods: Halogens (iodine, chlorine, bromine, and fluorine) |
somewhat denature proteins
helps with water purification |
| Chemical Methods: Oxidizing Agents - (Peroxides, Ozone, and peracetic acid) |
| Denature proteins by oxidation |
| Chemical Methods: Surfactants (Soaps and detergents) |
| Decrease surface tension of water and disrupt cell membranes |
Chemical Methods: Heavy Metals (arsenic, zinc, mercury, silver copper), Aldehydes (glutaraldehydes and formaldehyde), Gaseous Agents (ethylene oxide, propylene oxide, and beta-propiolactone) |
| Denature Proteins |
| Chemical Methods: Antimicrobials |
| Act against cell walls, cell membranes, protein synthesis, and DNA transcription and replication |
| Sterilization |
| Refers to the removal or destruction of all microbes, including viruses and bacterial endospores, in or on an object. (Does not apply to prions, which are infectious proteins, because standard sterilizing techniques do not destroy them.) |
Disinfection
(Unlike sterilization, disinfection does not guarantee that all pathogens are eliminated. Disinfectants alone cannot inhibit endospores or some viruses.) |
Refers to the use of physical or chemical agents known as disinfectants including ultraviolet light, heat, alcohol, and bleach, to inhibit or destroy microorganisms, especially pathogens. This term only used when discussing inanimate objects.
|
Antisepsis
(Antiseptics and disinfectants often have the same components, but disinfectants are more concentrated or can be left on a service for longer periods of time.) |
| When a chemical is used on skin or other tissue. |
| DEGERMING |
| Is the removal of microbes from a surface by scrubbing, such as when you wash your hands or a nurse prepares an area of skin for an injection. The action of throughly scrubbing the surface may be more important than the chemical in removing microbes. |
| Sanitization |
| Is the process of disinfecting places and utensils used by the public to reduce the number of pathogenic microbes to meet aceepted public health standards. The difference between disinfecting dishes at home and sanitizing dishes in a restaurant is the arena - private versus public. |
| Pasteurization |
| Is the use of heat to kill pathogens and reduce the number of spoilage microorganisms in food and beverages. |
| -stasis/-static control agent |
Indicates that a chemical or physical agent inhibits microbial metabolism and growth, but doesn't necessarily kill microbes. Refrigeration is bacteriostatic for most bacterial species; it inhibits their growth, but they can resume metabolism when the optimal temperature is restored. |
| -cide/-cidal control agent |
Refers to agents that destroy or permanently inactivate a particular type of microbe ; Virucides inactivate viruses Bactericides kill bacteria Fungicides kill fungal hyphae, spores, and yeasts Germicides are chemical agents that destroy pathogenic microorganisms in general. |
| Microbial Death Rate |
The permanent loss of reproductive ability under ideal environmental conditions. The MDR is constant over time for any particular microorganism under a particular set of conditions. Remember constant |
| List factors to consider in selecting a microbial control method |
- Site to Be Treated - Relative Susceptibility of Microorganisms - Environmental Conditions ; |
Identify the three Most resistant groups of microbes: - Why are they resistant to many antimicrobial agents |
-bacterial endospores (such as Bacillus and Clostridium can survive extreme temps. and acidity, and many chemical disinfectants) ; - Species of Mycobacterium (the cell walls of members of this genus, contain large amounts of waxy lipids. The wax allows these bacteria to survive drying and protects them from water-based chemicals) ; - Cysts of protozoa prevents entry of most disinfectants, protects against drying, and shields against radiation and heat. |
| Environmental Conditions that can influence the effectiveness of Antimicrobial Agents: |
Temperature and pH ; Organic materials such as fat, feces, vomit, blood, and the intercellular secretions in biofilms interfere with the penetration of heat, chemicals, and some forms of radiation. |
| Compare and contrast four methods used to measure the effectiveness of disinfectants and antiseptics. |
1. Phenol Coefficient A phenol coefficient greater than 1.0 indicates that an agent is more effective than phenol, and the larger the ration, the greater the effectiveness. ; 2. Use-Dilution Test A researcher dips several metal cylinders into broth cultures of bacteria and briefly dries them at37C. 3. Kelsey-Sykes Capacity Test Is a standard alternative assessment approved by the European Union to determine the capacity of a given chemical to inhibit bacterial growth. Add a suspension of a bacterium such as S.aureus to a suitable concentration of the chemical being tested. 4. In-Use Test A more realistic (though more time-consuming) method for determining the efficacy of a chemical is called an in-use test. In this procedure, swabs are taken from actual objects, such as operating room equipment, both before and after the application of disinfectant or an antiseptice. Inoculate swabs in a growth media and examine for microbial growth. This allows a more accurate determination of the proper strength and application procedure of a given disinfection agent for each specific situation. |
| Describe five types of physical methods of microbial control: |
- Exposure of the microbes to extremes of heat and cold. - Desiccation: drying - Filtration: is the passage of a fluid through a sleeve designed to trap particles. - Osmotic Pressure: use of high concentrations of salt or sugar in foods to inhibit microbial growth. - Radiation: ionizing or non ionizing (ionizing - wavelengths shorter than 1nm: electron beams, gamma rays, and X rays) (Non-ionizing - electromagnetic radiation with a wavelength greater than 1 nm does not have enough energy to force electrons out of orbit.) |
| Discuss the advantages and disadvantages of using moist heat in an autoclave and dry heat in an oven for sterilization: |
Moist heat is used to disinfect, sanitize, sterilize, and pasteurize, kills cells by denaturing proteins and destroying cytoplasmic membranes. Moist heat is more effective in microbial control than dry heat because water is a better conductor of heat than air. Sterilization in an autoclave requires that steam be able to contact all liquids and surfaces that might be contaminated with microbes. (15 min process) Hot Dry Air is an effective sterilizing agent because it denatures proteins and fosters the oxidation of metabolic and structural chemicals. Dry heat requires higher temps for longer times than moist heat b/c dry heat penetrates more slowly. (16 hour process) |
| Describe the use of boiling water as a means of disinfection: |
Boiling kills the vegetative cells of bacteria and fungi, the trophozoites of protozoa, and most viruses within 10 minutes at sea level. Boiling time is the critical factor. Water boils at lower temps at higher elevations b/c atmospheric pressure is lower. ; Desiccation inhibits microbial growth b/c metabolism requries liquid water. Drying inhibits the spread of most pathogens, including the bacteria that causes syphilis, gonorrhea, and diarrhea. |
| Explain the importance of pasteurization and describe the process: |
| denatures proteins and destroys membranes - destruction of all pathogens and most spoilage microbes in dairy products, fruit juices, beer, and wine. Pasteurization is NOT Sterilization. |
| Describe the use of refrigeration and freezing in limiting microbial growth. |
Refrigeration halts the growth of most pathogens, which are predominantly mesophiles. Slow freezing, during which ice crystals have time to form and puncture cell membranes, is more effective than quick freezing in inhibiting microbial metabolism, though microorganisms also vary in their susceptibility to freezing. |
| Compare and contrast dessication and lyophilization: |
Lyophilization is a technique combining freezing and drying, to preserve microbes and other cells for many years. Drying/Dessication inhibits microbial growth by removing water that microbes need for metabolism. |
| Describe the use of filters for disinfection and sterilization: |
| Filtration is the passage of a fluid (either a liquid or a gas) through a sieve designed to trap particles - in this case, cells or viruses - and separate them from the fluid. Filtration traps microbes larger than the pore size, allowing smaller microbes to pass through. |
| Discuss the use of hypertonic solutions in microbial growth: |
| From an area of higher water concentration to an area of lower water concentration - the removal of water inhibits cellular metabolism because enzymes are fully functional only in aqueous environments. |
| Differentiate between ionizing radiation and nonionizing radiation as they relate to microbial control: |
- Radiation: ionizing or non ionizing (ionizing - wavelengths shorter than 1nm: electron beams, gamma rays, and X rays) (Non-ionizing - electromagnetic radiation with a wavelength greater than 1 nm does not have enough energy to force electrons out of orbit.) |
| Compare and contrast nine major types of antimicrobial chemicals and discuss the positive and negative aspects of each. |
1. Phenols Positive: effective even in the presence of contaminating organic material such as vomit, pus, feces and they remain active on surfaces for a prolonged time. Negative: disagreeable odor and side effects of irritated skin, brain damage in infants. 2. Alcohols Positive: evaporate rapidly, leave no residue. Negative: may not contact microbes long enough to be effective. 3. Halogens Positive: evaporates slowly Negative: 4. Oxidizing Agents Positive: Negative: 5. Surfactants Positive: Negative: 6. Heavy Metals Positive: Negative: 7. Aldehydes Positive: Negative: 8. Gaseous Agents Positive: Negative: 9. Enzymes Positive: Negative: |
