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71 Cards in this Set
- Front
- Back
- 3rd side (hint)
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When did scientific study of control of microbial growth begin? |
125-150 years ago |
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In the 1800s, what percentage of delivering mothers died of hospital acquired infection? |
25% |
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What era is associated with the bubonic plague epidemic? |
14th-17th century |
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What is the estimated number of deaths resulting from the bubonic plague epidemic? |
40 million, or 1/3 of the population of the European continent |
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Etiological agent of the bubonic plague |
Yersinia pestis |
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Vector of the bubonic plague? |
Fleas, typically carried by rats |
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How does the bubonic plague begin? |
Begins with a bite from an infected flea or exposure to an infected person, leading to bacteremia , leading to bacteremia |
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Bacteremia |
Bacteria multiplying in the blood stream |
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How does a bubonic plague infection manifest? |
Bacteria localize in the lymph nodes, especially in the axillary and groin area Hemorrhaging occurs in lymph nodes, resulting in buboes |
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Buboes |
Black and blue swellings that occur as a result of the hemorrhaging of lymph nodes |
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If untreated, what is the mortality rate for the bubonic plague? |
50% |
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Pneumonic plague |
Septicemic plague that arises when a yersinia pestis infection spreads to the lungs More contagious than the bubonic plague |
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What is the mortality rate of the pneumonic plague? |
99% |
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Small pox |
A disease caused by the Variola virus After 1977, completely eradicated from nature due to vaccinations |
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Where does the Variola virus exist today? |
2 known samples are held in the CDC in Atlanta and Vector in Russia |
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Types of methods of controlling microbial growth |
1. Physical 2. Chemical |
2 |
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Chemical methods of controlling microbial growth |
1. Sterilization 2. Disinfection 3. Degerming 4. Sanitization |
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Sterilization |
Destroying all forms of life |
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Commercial Sterilization |
Sufficient heat to destroy endospores of Clostridium botulinum in canned food |
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Disinfection |
Destroying and/or inhibiting pathogens or unwanted organism |
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Disinfectant |
Antimicrobial agent used on inanimate objects |
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Antiseptic |
Antimicrobial agent used on living tissue |
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Bactericide |
Killing bacteria |
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Bacteristatic |
Inhibits bacterial growth |
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Algaecide |
An agent that kills algae |
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Fungistatic |
Inhibiting fungal growth |
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Degerming |
Removal of microbes from a limited area |
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Sanitization |
Treatment intended to lower microbial counts on eating and drinking utensils Done by high temperature wash or by dipping into a chemical disinfectant |
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Yersinia pestis |
A gram negative rod bacteria that is the etiological agent of the bubonic plague |
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What would you call using an alcohol swab to clean an injection site |
Degerming |
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Factors that affect antimicrobial activity of disinfectants |
1. The number of microbes 2. Environmental influences 3. Time of exposure 4. Microbial characteristics |
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How does the number of microbes affect the antimicrobial activity of a disinfectant? |
The more bacteria in the beginning of the process, the harder it would be to kill the entire population |
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What are environmental influences that affect antimicrobial activity of disinfectants? |
1. Presence of organic material such as blood, vomit, or biofilms 2. Temperature (disinfectants are more effective at warmer temperatures) |
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How does time of exposure affect antimicrobial activity of disinfectants? |
Disinfectants may need extended time to affect more resistant microbes |
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What microbial characteristics can affect the antimicrobial activity of disinfectants? |
Some microbes are more resistant to disinfection, such as Gram negative bacteria, spores, and Mycobacterium |
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4 most resistant types of microbes from most to least |
1. Prions 2. Endospores of bacteria 3. Mycobacterium 4. Cysts of protozoans |
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Example of a prion? |
Mad cow disease |
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Why are Mycobacterium resistant? |
They are acid fast? |
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Cellular targets of antimicrobial agents |
1. Alteration of membrane permeability 2. Denature enzymes and other proteins 3. Damage Nucleic Acids, altering DNA and RNA |
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Physical methods of controlling microbial growth |
1. Heat 2. Radiation 3. Filtration 4. Refrigeration 5. High pressure 6. Desiccation 7. Osmotic pressure |
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How does heat control microbial growth? |
By denaturing proteins |
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Thermal death point (TDP) |
The lowest temperature at which all microbes and their endospores in a liquid culture are killed in 10 minutes |
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Thermal death time (TDT) |
The minimum length of time in which all microbes and their endospores in a liquid culture are killed at a given temperature |
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Types of heat methods |
1. Moist heat 2. Dry heat 3. Pasteurization |
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Moist heat methods |
1. Boiling water 2. Autoclave |
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Effectiveness of boiling water |
Kills vegetative bacterial cells, fungi, and many viruses Not effective against some viruses and endospores |
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Autoclave |
- Steam under pressure - Most common method of sterilization - water boils at 100C. Pressure increases the temp of the steam - typically 121C at 15psi for 20 minutes |
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Pasteurization |
A method of disinfection Used to control Mycobacterium in milk |
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Microbial condition of milk post pasteurization? |
<20,000 bacterial cells/mL |
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Disinfection |
Removes unwanted organisms |
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Methods of pasteurization |
1. Historically typical: 63C for 30 mins 2. High Temp Short Time (HTST) 3. Ultra High Temperature Treatments |
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HTST |
High temperature short- term pasteurization: 72C for 15 seconds |
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Ultra high temperature treatments |
140C for 4 seconds |
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Effectiveness of pasteurization |
Thermoduric bacteria can persist |
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thermoduric bacteria |
Not thermophiles, but can survive high temperatures |
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Methods of dry heat |
1. Direct flaming 2. Incineration 3. Hot air sterilization |
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Direct flaming |
Inoculating loop and needle sterilization 100% effective |
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Incineration |
Burning For disposable waste 100% effective |
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Hot air sterilization |
Oven at 170C for 2 hours Use on substances that should be damaged by moist heat |
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Filtration |
Physically removes microbes based on their size from solutions that might be damaged by heat |
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For what is filtration typically used? |
Culture media Enzymes Vaccines Antibiotics |
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Types of radiation used to control microbial growth |
1. Ionizing radiation 2. Non Ionizing radiation |
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Ionizing radiation |
- gamma and x-rays - penetrates most surfaces - completely disrupts DNA/RNA structure |
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What is Ionizing radiation typically used on? What can also be used on these materials? |
Substances that could be damaged by heat, such as; - plastic petri dishes - syringes - catheters - surgical gloves The gas ethylene oxide |
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Non Ionizing radiation |
- UV light - does not penetrate plastic, glass, or proteinaceous matter - causes pyrimidine dimers - Used to reduce microbial populations |
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Pyrimidine dimers |
Disrupt DNA at adjacent thymines |
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Where is non Ionizing radiation used to control microbial growth? |
- hospital rooms - operating rooms - biotechnology work benches and fume hoods |
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What is a common use for high pressure? |
To preserve some fruit juices |
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Desiccation |
Absence of water Freeze drying |
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Osmotic pressure |
Using high concentrations of salt and sugars to create hypertonic environments |
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Which is the faster process of sterilization: dry or most heat? Why? |
Moist. Water is a better conductor of heat than air |
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