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Micro Exam Ch7
The Control of Microbial Growth
| Question | Answer |
|---|---|
| What is the removal or destruction of all living microorganisms (including endospores)? | Sterilization |
| What is a sterilizing agent called? | Sterilant |
| What is a limited heat treatment, enough to kill Clostridium botulinum endospores? | Commercial sterilization |
| What is the process of removing vegetative pathogens (disease-causing microbes) on inanimate objects? | Disinfection |
| What process destroys vegetative growth, not endospores? | Disinfection |
| What is the disinfection of living tissue? | Antisepsis |
| What is the chemical called for the treatment antisepsis? | Antiseptic |
| What is the process of swabbing the skin with alcohol to remove microbes for sanitization? | Degerming |
| What is intended to lower microbial counts to safe public health levels and minimize the chances of disease transmission from one user to another? | Sanitization |
| What is a substance that kills microbes (usually with certain exceptions, such as endospores)? | Biocide/germicide |
| What is the inhibiting, not killing, of microbes? | Bacteriostasis |
| What word comes from the Greek word for decay or putrid, and indicates bacterial contamination, such as in septic tanks, for sewage treatment? | Sepsis |
| What is the absence of significant contamination? | Aseptic |
| What are some of the factors that influence the effectiveness of antimicrobial treatments? | ·The number of microbes (starting with more = longer to kill) ·Environmental influences (organic matter, temperature, biofilms, pH) · Time of exposure ·Microbial characteristics ·Concentration of disinfectant (for chemical disinfectants) |
| What are some of the ways various agents actually kill or inhibit microbes? | ·Alteration of membrane permeability ·Damage to proteins ·Damage to nucleic acids |
| What are the physical methods of microbial count? | ·Heat (Moist and dry heat sterilization) ·Filtration ·Low temperatures (Refrigeration, freezing) ·High pressure ·Desiccation ·Osmotic pressure ·Radiation |
| What is one of the most common methods of food preservation and sterilization of equipment and kills microbes by denaturing their enzymes and other components of cells? | Heat |
| What is the lowest temperature at which all the microorganisms in a particular liquid suspension will be killed in 10 minutes? | Thermal death point (TPD) |
| What is the minimal length of time for all bacteria in a particular liquid culture to be killed at a given temperature? | Thermal death time (TDT) |
| What is the time, in minutes, in which 90% of a population of bacteria at a given temperature will be killed? | Decimal reduction time (DRT) |
| What heat sterilization kills microorganisms primarily by coagulating proteins (denaturation), which is caused by breakage of hydrogen bonds that holds the proteins in their three-dimensional structure? | Moist heat sterilization |
| What are the three types of moist heat sterilization? | Boiling, autoclaving, and pasteurization |
| How long does boiling take to kill most pathogens? | 10 minutes |
| Some hepatitis viruses can survive __ minutes of boiling | 30 minutes |
| Some endospores can resist boiling for more than __ hours | 20 hours |
| What machine uses steam under pressure to kill harmful bacteria? | Autoclave |
| Higher pressure in an autoclave means _____ temperature | Higher |
| An ______ is most effective when the steam can directly contact the item or the volume is small | Autoclave |
| What is an autoclave used to sterilize? | Culture media, instruments, and biohazardous waste |
| Autoclaves kill even most endospores within 15 minutes at a steam pressure of __ psi (121°C) | 15 psi |
| The intent of ________ of milk was to eliminate pathogenic microbes. This process reduces spoilage organisms and pathogens | Pasteurization |
| What are relatively heat-resistant bacteria that survive pasteurization and are unlikely to cause disease or cause refrigerated milk to spoil? | Thermoduric organisms |
| What milk pasteurization uses temperatures of at least 72°C for 15 seconds and is applied as the milk flows continuously past a heat exchanger? | High-temperature short-time pasteurization (HTST) |
| What is the concept that as the temperature is increased, much less time is needed to kill the same number of microbes? | Equivalent treatments |
| What type of sterilization kills by oxidation effects? | Dry heat sterilization |
| What is one of the simplest methods of dry heat sterilization used to sterilize inoculating loops? | Flaming |
| What is an effective way to sterilize and dispose of contaminated paper cups, bags, and dressings? | Flaming |
| What form of dry heat sterilization requires items to be placed in an oven, generally at a temperature of about 170°C maintained for nearly 2 hours and ensures sterilization? | Hot-air sterilization |
| What is the passage of a liquid or gas through a screenlike material with pores small enough to retain microorganisms? | Filtration |
| What type of filters remove almost all microorganisms larger than about 0.3 um in diameter? | HEPA |
| What means that the agent prevents the growth of bacteria? | Bacteriostatic |
| High pressure denatures ______ | Proteins |
| In the absence of water, known as _______, microorganisms cannot grow or reproduce but can remain for years | Dessication |
| Freeze-drying is an example of _________ | Dessication |
| What are the three types of ionizing radiation? | Gamma rays, X rays, and high-energy electron beams |
| What has a shorter wavelength than that of nonionizing radiation and therefore carries much more energy? | Ionizing radiation |
| What are emitted by certain radioactive elements such as cobalt? | Gamma rays |
| Electron beams are produced by accelerating electrons to high energies in special machines, and ______ , which are produced by machines in a manner similar to the production of electron beams, are similar to gamma rays | X rays |
| Gamma rays penetrate deeply but may require hours to sterilize large masses; ___-____ ______ _____ have much lower penetrating power but usually require only a few seconds of exposure | High-energy electron beams |
| What ionizes water to release OH+? | Ionizing radiation |
| What radicals kill organisms by reacting with organic cellular components, especially DNA, and damaging them? | Ionizing radiation |
| What is used to sterilize disposable dental and medical supplies, processing certain meats and vegetables, etc.? | Ionizing radiation |
| What has a wavelength longer than that of ionizing radiation, usually greater than about 1 nm | Nonionizing radiation |
| What radiation includes UV and longer wavelengths? | Nonionizing radiation |
| __ light damages the DNA of exposed cells by causing bonds to form between adjacent pyrimidine bases, usually thymines, in DNA chains? | UV |
| What is used to disinfect the air, vaccines, etc.? | UV radiation |
| What is a disadvantage of UV radiation? | It is not very penetrant |
| What machines kill most pathogens by heat but are not especially antimicrobial? | Microwaves |
| Acts rapidly (all), wide range, able to penetrate contaminated material, water-soluble or readily forms an emulsion, not hampered by organic matter in the thing being disinfected, stable over time, even unfavorable environmental conditions, not corrosive | Characteristics of a good disinfectant |
| No single disinfectant appropriate for all circumstances, few chemical agents achieve sterility.Most reduce numbers to safe levels, Disinfection is a gradual process, death curves, Antimicrobials are not useful for ingestion, various factors influence | The reality of chemical methods of disinfection |
| What are some factors that influence the effectiveness of chemical disinfection? | Number of microbes, environment (organic matter, temperature, biofilms, pH), time of exposure, microbial characteristics, concentration of disinfectant |
| What test is used to evaluate the effectiveness of disinfectants and antiseptics? | Use-dilution test |
| In what use-dilution method is a filter paper disk soaked with a test chemical and placed on an agar plate that was inoculated with a test organism? | Disk-diffusion method |
| What do clear zones around a disk indicate in the disk-diffusion method? | Effective microbial inhibition |
| This is also known as carbolic acid and it disrupts plasma membranes to control odor in sewage, but it is now rarely used as an antiseptic or disinfectant because it irritates the skin and has a disagreeable odor | Phenol |
| What are derivatives from phenol that contain a molecule of phenol that has been chemically altered to reduce its irritating qualities or increase its antibacterial activity in combination with a soap or detergent? | Phenolics |
| One of the most frequently used phenolics is derived from coal tar, a group of chemicals called ______ | Cresols |
| Lysol's active ingredient is often ___________ (a very important cresol) | O-phenylphenol |
| Derivatives of phenol that contain two phenolic groups connected by a bridge | Bisphenols |
| A widely used bisphenol that was used in bacterial soap | Triclosan |
| Halogens, particularly ______ and ______, are effective antimicrobial agents, both alone and as constituents of inorganic or organic compounds | Iodine and chlorine |
| What antiseptic alters protein synthesis and membranes by forming complexes with amino acids and unsaturated fats? It is also effective against all kinds of bacteria, many endospores, various fungi, and some viruses | Iodine (I2) |
| The most common commercial preparation of iodine is ________ (povidone-iodine) for skin disinfection or wound treatment | Betadine |
| What is a carrier molecule that improves the wetting action of iodine and provides a reservoir of free iodine? | Povidone |
| Germicidal action is caused by the hypochlorous acid (HOCl) that forms when ______ is added to water | Chlorine |
| What antiseptic is a strong oxidizing agent that prevents much of the cellular enzyme system from functioning? | Chlorine |
| What is formed when chlorine is added to water? | Hypochlorous acid (HOCl) |
| What chlorine compound is used as a household disinfect and bleach (Clorox), and as a disinfectant in dairies, food-processing establishments, and hemodialysis systems? | Sodium hypochlorite (NaOCl) |
| What chlorine compound is made of ammonia and chlorine and is used in municipal water treatment in several cities in the US and Europe? | Chloramines |
| What effectively kill bacteria and fungi but not endospores and nonenveloped viruses? It usually denatures protein, but it can also disrupt membranes and dissolve many lipids, including the lipid component of enveloped viruses | Alcohols |
| What is an advantage of alcohol use? | Act and evaporate rapidly |
| What are two of the most commonly used alcohols? | Ethanol and isopropanol |
| What is the recommended optimum concentration of ethanol? | 70% |
| Why is pure ethanol less effective than aqueous solutions (ethanol mixed with water)? | Because denaturation requires water |
| What are two alcohol-based sanitizers? | Germ-X and Purell |
| What is the most widely used surfacant? | Quaternary ammonium |
| What is a common example of a quaternary ammonium compound? | Zephiran ( a brand name of benzlkonium chloride) |
| What are surface-active agents such as quaternary ammonium (detergents), alcohols, and some antibiotics targets to? | The plasma membrane |
| How are alcohols, quaternary ammonium (detergents), and some antibiotics damaging to the plasma membrane? | They cause leakage of cell contents |
| Surface-active agents, or surfacants, can decrease surface ______ among molecules of a liquid | Tension |
| T or F: Water is cohesive | True |
| Soaps and detergents are examples of _______ | Surfacants |
| What surfacant is used for degerming and is not in itself antibacterial? | Soap |
| What is a common exmample of soap? | Sodium stearate |
| Soap breaks the oily film on skin into tiny droplets, a process called _______, and the water/soap combination wash away the emulsified oil and debris | Emulsifaction |
| What are soaps typically made of? | Fatty acids and oils |
| What are the two chemical food preservatives? | 1. Organic acids (or salts of organic acids) 2. Nitrites (sodium nitrate or nitrite) |
| What chemical food preservatives inhibit metabolism or plasma membrane integrity? | Organic acids |
| The two organic acids, sorbic acid (potassium sorbate) and benzoic acid (sodium benzoate) prevent _____ growth in certain acidic foods, such as cheese | Mold |
| ______ _____ control molds and bacteria in foods and cosmetics (fungistatic) | Organic acids |
| What chemical food preservative prevents botulism endospore growth? | Nitrites (sodium nitrate or nitrite) |
| ______ are often found in processed meats such as hot dogs, bacon, etc. | Nitrites |
| Nitrite selectively inhibits certain iron-containing enzymes of _______ ______ | Clostridium botulinum |
| What are a group of oxidizing agents that include hydrogen peroxide (H2O2), benzoyl peroxide (often in over-the-counter acne treatments, and ozone (O3)? | Peroxygens |
Created by:
malele-sedlacek
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