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256 Cards in this Set
- Front
- Back
sterilization |
removal or destruction of all living microorganisms 0 heating is most common method , which is efficient against endospores |
|
sterilizing agent is called a |
sterilant |
|
liquid or gas can be sterilized by |
filtration |
|
commercial sterilization |
food heated enought to destroy the endospores of clostridumm boulinum |
|
control directed at destroying harmful microorgainsms is called |
disinfection - usualy refers to destruction of vegetative (non- endospore forming) pathogen |
|
________ might make use of chemicals, ultraviolet radiation, boiling water, or steam. In practice, the term is most commonly applied to the use of a chemical (a disinfectant) to treat an inert surface or substance. |
Disinfection |
|
when disinfect is directed at living tissue it is called |
antisepsis and the chemical is called an antiseptic |
|
degerming |
removal rather than killing of most microbes in a limited area |
|
intended to lower microbial counts to safe terms |
sanitization |
|
- cide |
kill |
|
biocide or germicide kills |
microorganissm (except endospores) |
|
fungicide kills |
fungi |
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virucide |
inactivates viruses |
|
-stat or -stasis |
stop or to stead |
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once a bacteriostatic agent is removed |
growth might resume |
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Destruction or removal of all forms of microbial life, including endospores but with the possible exception of prions. - Usually done by steam under pressure or a sterilizing gas, such as ethylene oxide. |
sterilization |
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Sufficient heat treatment to kill endospores of Clostridium botulinum in canned food. - More-resistant endospores of thermophilic bacteria may survive, but they will not germinate and grow under normal storage conditions. |
commercial sterilization |
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Destruction of vegetative pathogens on inanimate objects. - May make use of physical or chemical methods. |
disinfection |
|
destruction of vegetative pathogens n living tissue - Treatment is almost always by chemical antimicrobials. |
antisepsis |
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Removal of microbes from a limited area, such as the skin around an injection site. - Mostly a mechanical removal by an alcohol-soaked swab. |
degerming |
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Treatment is intended to lower microbial counts on eating and drinking utensils to safe public health levels. - May be done with high-temperature washing or by dipping into a chemical disinfectant. |
sanitization |
|
aseptic meanas |
object or area is free of pathogens |
|
absence of significant contamination |
asepsis |
|
factors that influence the effectiveness of antimicrobial treatments |
●The number of microbes. The more microbes there are to begin with, the longer it takes to eliminate the entire population. ● Environmental influences. Most disinfectants work somewhat better in warm solutions. |
|
The more microbes there are to begin with, |
the longer it takes to eliminate the entire population. |
|
Most disinfectants work somewhat better in |
warm solutions. |
|
plotting the typical microbial death curve logarithmically results ins a |
straight line
|
|
medium rich in fats and proteins |
protects microbes - makes them have a higher survival rate |
|
plotting the typical microbial death curve arithmetically |
is impractical |
|
if rate of killing is the same it will take longer to kill |
all members of a larger population
|
|
- Bacterial populations usually die at a constant rate when heated or when treated with antimicrobial chemicals. - It is necessary to use logarithmic numbers to graph bacterial populations effectively. - Understanding logarithmic death curves for microbial populations, including the elements of time and the size of the initial population, is especially useful in food preservation and in the sterilization of media or medical supplies. |
ya |
|
damage to the lipids or proteins of the plasma membrane by antimicrobial agents causes |
cellular contents to leak into the surrounding medium and interferes with the growth of the cell |
|
desiccation through lyophilization |
drying - microorganisms cannot grow or reproduce but can remian viable for years. when water is available hey can contiue to grow and divide |
|
osmotic pressure |
use of high concentrations of salts and sugars - creates hypertonic environment which causes water to leave the microbial cell which denies the moisture needed to grow |
|
Heat appears to kill microorganisms by |
denaturing their enzymes; the resultant changes to the three-dimensional shapes of these proteins inactivate them |
|
thermal death point TDP |
the lowest temperature at which all the microorganisms in a particular liquid suspension will be killed in 10 minutes. |
|
thermal death time (TDT), |
the minimal length of time for all bacteria in a par- ticular liquid culture to be killed at a given temperature. |
|
TDP and tdt INDICATE |
severity of treatment required to kill a gien population of bacteria |
|
Decimal reduction time DRT |
DRT is the time, in minutes, in which 90% of a population of bacteria at a given temperature will be killed |
|
Moist heat kills microorganisms primarily by |
coagulating proteins (denaturation) |
|
bried boiling will kill |
most pathogens |
|
Autoclaving is the preferred method of sterilization in health care environments, unless the material to be sterilized can be damaged by heat or moisture. The higher the pressure in the autoclave, the higher the temperature. |
ya |
|
steam at a pressure of about _____________ will kill all organisms (but not prions; see page 195) and their endospores in about 15 minutes. |
15 psi (121°C) |
|
large indutrial autoclabes are called |
retorts |
|
steam cant penetrate |
aluminum foil |
|
pasteurization |
to eliminate pathogenic microbes and lower microbial numbers - thermoduric surivive pasteriuzation- unlikely to cause disease |
|
thermoduric |
heat resistant bacteria |
|
phosphatase test |
whether products have been pasteurized - if pasterized, phosphatase is inactivated |
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high- temperature short-time (HTST) pasteurization, is applied as the milk flows continuously past a heat exchanger |
at least 72 c for 15 sec |
|
ultra high temperature treatments UHT |
sterilization, refrigeration not needed |
|
equivalent treatments: |
as the temperature is in- creased, much less time is needed to kill the same number of microbes. |
|
Dry heat kills by |
oxidation effects |
|
One of the simplest methods of dry heat sterilization is |
direct flaming. |
|
_________ is the passage of a liquid or gas through a screenlike material with pores small enough to retain microorganisms - used to sterilize heat sensitive materials, media, enzymes, vaccines, and antibiotic solutions |
Filtration |
|
High-efficiency particulate air (HEPA) filters remove |
almost all microorganisms larger than about 0.3 μm in diameter. |
|
membrane filters composed of |
cellulose esters or plastic polymers - These filters are only 0.1 mm thick. The pores of membrane filters, for example, 0.22-μm and 0.45-μm sizes, are intended for bacteria. Some very flexible bacteria, such as spirochetes, or the wall-less mycoplasma, will sometimes pass through such filters, however. Filters are available with pores as small as 0.01 μm, a size that will retain viruses and even some large protein molecules. |
|
pathogenic bacteria generally will not growh at refrigerator temperatures but _____ is an important exception |
listeria |
|
Radiation that kills microorganisms (sterilizing radiation) is of two types: |
ionizing and nonionizing |
|
_______________gamma rays, X rays, and high-energy electron beams—has a wavelength shorter than that of nonionizing radiation, less than about 1 nm. Therefore, it carries much more energy |
ionizing radiation |
|
Ionizing radiation, especially high-energy electron beams, is used to sterilize |
pharmaceuticals and disposable dental and medical supplies, such as plastic syringes, surgical gloves, suturing materials, and catheters. |
|
Nonionizing radiation has a wavelength _________than that of ionizing radiation, usually greater than about 1 nm. |
longer |
|
The best example of nonionizing radiation is |
ultraviolet (UV) light. UV light damages the DNA of exposed cells by causing bonds to form between adjacent pyrimidine bases, usually thymines, in DNA chains |
|
Microwaves do not have much direct effect on microorgansms, and bacteria can readily be isolated from the interior of recently operated microwave ovens. Moisture-containing foods are heated by microwave action, and the heat will kill most vegetative pathogens. |
ya |
|
moist heat 2 methods |
boiling or flowing steam and autoclabing |
|
boiling or flowing steam |
- protein denaturation - Kills vegetative bacterial and fungal pathogens and almost all viruses within 10 min; less effective on endospores. - dishes |
|
autoclaving |
- protein denaturation - Very effective method of sterilization; at about 15 psi of pressure (121°C), all vegetative cells and their endospores are killed in about 15 min. |
|
pasteurization |
- protein denaturation - Heat treatment for milk (72°C for about 15 sec) that kills all pathogens and most nonpathogens. - milk, beer and wine |
|
dry heat 3 methods |
direct flaming, incineration, hot air sterilzation |
|
direct flaming |
- burning contaminants to ashes - Very effective method of sterilization. - innoculating loops |
|
incineration |
- burning to ashes - Very effective method of sterilization. |
|
hot air sterilization |
- oxidation - Very effective method of sterilization. but requires temp of 170 c for about 2 hr - glasswear |
|
filtration |
- seperation of bacteria from suspending liquid - Removes microbes by passage of a liquid or gas through a screenlike material; most filters in use consist of cellulose acetate or nitrocellulose. - Useful for sterilizing liquids (e.g., enzymes, vaccines) that are destroyed by heat |
|
heat methods used to control microbial growth |
- moist heat (boiling and autoclaving) - pasteurization - dry heat (direct flaming, incineration, hot air sterilization) |
|
cold methods used to control microbial growth |
- refrigeration - deep freezing - lyophilization |
|
refrigeration |
- Decreased chemical reactions and possible changes in proteins - has a bacteriostatic effect - food, drug preservation |
|
deep freezing |
- Decreased chemical reactions and possible changes in proteins - An effective method for preserving microbial cultures, in which cultures are quick- frozen between − 50° and − 95°C. |
|
lyophilization |
- Decreased chemical reactions and possible changes in proteins - Most effective method for long-term preservation of microbial cultures; water removed by high vacuum at low temperature. |
|
high pressure |
- alteration of molecular structure of proteins and carbohydrates - preserves colors, flavors, nutrent values - juices |
|
dessication |
- disruption of metabolism - involves removing water from microbes; primarily bacteriostatic |
|
osmotic pressure |
- plasmolysis - results in loss of water from microbial cells |
|
radiation methods used to control microbial growth |
ionizing and nonionizing |
|
ionizing radiation |
- destruction of dna - not widespread in routine steriliztion - sterilizing pharmaceuticals and medical and dental supplies |
|
nonionizing radiation |
- damage to dna - radiation is not very penetrating - control of closed environment with uv ( germicidal ) lamp |
|
___________is used in teaching laboratories to evaluate the efficacy of a chemical agent. |
disk-diffusion method |
|
lister was the first to use |
phenol ( carbolic acid ) - control surgical infections in the operating room |
|
derivatives of phenol called phenolics contain a molecule of |
phenol that has been chemically altered to reduce its irritating qualitites or increase its antibacterial activity in combination with a soap or detergent |
|
Phenolics exert antimicrobial activity by |
injuring lipid-containing plasma membranes, which results in leakage of cellular contents. |
|
bisphenols |
derivatives of phenol that contain two phonlic groups connected by a bridge |
|
Triclosan - bisphenol |
inhibits an enzyme needed for the biosynthesis of fatty acids (lipids), which mainly affects the integrity of the plasma membrane. - especially effective against gram-positive bacteria, yeasts, and gram - negative bacteria - not effective against pseudomonas aeruginosa |
|
__________ have a broad spectrum of activity, with a mode of action primarily affecting bacterial cell membranes. They are especially effective against gram-positive bacteria. Biguanides are also effective against gram-negative bacteria, with the significant exception of most pseudomonads. Biguanides are not sporicidal but have some activity against enveloped viruses - ex. chlorhexidine |
Biguanides
|
|
halogens, particularly____________, are effective antimicrobial agents, both alone and as constituents of inorganic or organic compounds. |
iodine and chlorine |
|
Iodine (I2) is one of the oldest and most effective antiseptics. It is active against all kinds of bacteria, many endospores, various fungi, and some viruses. Iodine impairs protein synthesis and alters cell membranes, apparently by forming complexes with amino acids and unsaturated fatty acids. |
ya |
|
tincture |
solution in acqueous alcohol |
|
iodophor |
combination of iodine and organic molecule where iodine is realeased slowly - do not stain and are less irritating |
|
chlorine has germicidal action caused by |
hypochlorous acid HOCl that forms when chlorine is added to water |
|
Hypochlorite is a strong oxidizing agent that prevents much of the cellular enzyme system from functioning. Hypochlorous acid is the most effective form of chlorine because it is neutral in electri- cal charge and diffuses as rapidly as water through the cell wall. |
ya |
|
chloramines |
combinations of chlirne and ammonia -toxic to acquarium fish - relatively effective in organic matter but have the disadvantages ofacting more slowly and being less effective than hypochlorite. |
|
__________effectively kill bacteria and fungi but not endospores and nonenveloped viruses. |
Alcohols |
|
_______ usually denatures protein, but it can also disrupt membranes and dissolve many lipids, including the lipid component of enveloped viruses. |
Alcohol |
|
Two of the most commonly used alcohols are |
ethanol and isopropanol. - The recommended optimum concentration of ethanol is 70%, but concentrations between 60% and 95% seem to kill as well - pure ethanol is less effective than aqueous solutions because denaturation requires water |
|
viruses that lack a lipid envelop are resistant to |
alcohol based hand sanitizers |
|
The ability of very small amounts of heavy metals, especially silver and copper, to exert antimicrobial activity is referred to as |
oligodynamic action - When the metal ions combine with the sulfhydryl groups on cellular proteins, denaturation results. |
|
surface active agents or surfactants cand |
decrease surface tension among molecules of a liquid - soap and detergents |
|
Soap breaks the oily film into tiny droplets, a process called _________, and the water and soap together lift up the emulsified oil and debris and float them away as the lather is washed off. |
emulsification |
|
Acid-anionic sanitizers are very important in cleaning food-processing facilities, especially dairy utensils and equipment. They are usually combinations of phosphoric acid with a surface-active agent. Their sanitizing ability is related to the negatively charged portion (anion) of the molecule, which reacts with the plasma membrane. |
ya |
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The most widely used surface-active agents are the cationic detergents, especially the ________ - especially bactericidal against gram positive bacteria - fungicidal, embicidal, and virucidal against enveloped viruses - they do not kill endospores or mycobacteria - change the cells permeability and cuase the loss of essentiaal cytoplasmic consitutents such as potassium - pseudomonas survive and grow in quats |
quaternary ammonium compounds (quats). |
|
Their name is derived from the fact that they are modifications of the four-valence ammonium ion, NH4+ |
quats |
|
Chemical preservatives are frequently added to |
foods to retard spoilage. - Sulfur dioxide (SO2) has long been used as a disinfectant, especially in wine-making. |
|
There has been some concern that the reaction of nitrites with amino acids can form certain carcinogenic products known as |
nitrosamines |
|
Aldehydes are among the most effective antimicrobials. Two examples are |
formaldehyde and glutaraldehyde. |
|
the gaseous chemosterilants are frequently used as |
substitutes for physical sterilization processes. |
|
plasma |
- fourth state of matter where gas is excited by an electromagentic field to make a mixutre of nuclei with assortedelectrical charges adn free elctrons |
|
plasmas have many free radicals that quickly destroy |
endospore forming microbes - requires only low tempreratures |
|
The use of supercritical fluids in sterilization combines |
chemical and physical methods. - When carbon dioxide is compressed into a “supercritical” state, it has properties of both a liquid (with increased solubility) and a gas (with a lowered surface tension). |
|
Peroxygens are a group of oxidizing agents that includes |
hydrogen peroxide and peracetic acid. |
|
Although ozone is a more effective killing agent than chlorine, its residual activity is |
difficult to maintain in water. |
|
Many biocides tend to be more effective against |
gram-positive bacteria, as a group, than against gram-negative bacteria. -A principal factor in this relative resistance to biocides is the negative bacteria |
|
bacterial endospores are affected by relatively few |
biocides |
|
The resistance of viruses to biocides largely depends on the presence or absence of __________ |
an envelope. |
|
Antimicrobials that are lipid- soluble are more likely to be effective against |
enveloped viruses. |
|
Nonenveloped viruses, which have only a protein coat, are more |
resistant—fewer biocides are active against them. |
|
to destroy prions |
combined use of a solution of sodium hydroxide and autoclaving at 134°C. |
|
phenol |
- Disruption of plasma membrane, denaturation of enzymes. - rarely used, used for comparison, irritating qualities |
|
phenolics |
- Disruption of plasma membrane, denaturation of enzymes. - environmental surfaces, instruments, skin surfaces, mucous membranes - derivative of phenol that is reactive even in the presence of organic material |
|
bisphenols |
- probably disruption of plasma membrane - disinfectant hand soaps and skin lotions - triclosan - broad spectrum - most effective against gram positives |
|
bisguanides (chlorhexidine) |
- disruption of plasma membrane - skin disinfection - Bactericidal to gram-positives and gram- negatives; nontoxic, persistent. |
|
halogens |
- Iodine inhibits protein function and is a strong oxidizing agent; chlorine forms the strong oxidizing agent hypochlorous acid, which alters cellular components. - Iodine is an effective antiseptic available as a tincture and an iodophor; chlorine gas is used to disinfect water; chlorine compounds are used to disinfect dairy equipment, eating utensils, household items, and glassware. |
|
alcohols |
- protein denaturation and lipid dissolution - Bactericidal and fungicidal, but not effective against endospores or nonenveloped viruses; commonly used alcohols are ethanol and isopropanol. |
|
heavy metals and their compounds |
- denaturation of enzymes and other essential proteins - Silver nitrate may be used to prevent ophthalmia neonatorum; silver-sulfadiazine is used as a topical cream on burns; copper sulfate is an algicide. - Heavy metals such as silver and mercury are biocidal. |
|
surface active agents |
- soap and detergents - acid anionic sanitizers - quaternary ammonium compounds ( cationic detergents ) |
|
soap and detergents |
- mechanical removal of microbes through scrubbing - skin degerming and removal of debris |
|
acid anionic sanitizers |
- may involve enzyme inactivation or disruption - sanitzers in dairy and food processing industires |
|
quaternary ammonium compounds ( cationic detergents ) |
- enzyme inhibition, protein denaturation, disruption of plasma membranes - antiseptic for sking, instruments, rubber goods - Bactericidal, bacteriostatic, fungicidal, and virucidal against enveloped viruses. Examples of quats are Zephiran and Cepacol. |
|
Organic acids |
- Metabolic inhibition, mostly affecting molds; action not related to their acidity. - used to control mold and some bacteria |
|
nitrates/ nitrites |
- Active ingredient is nitrite, which is produced by bacterial action on nitrate. Nitrite inhibits certain iron- containing enzymes of anaerobes. - Prevents growth of Clostridium botulinum in food; also imparts a red color |
|
aldehydes |
- protein denaturation - Glutaraldehyde (Cidex) is less irritating than formaldehyde and is used for disinfecting medical equipment. - very effective antimicrobials |
|
chemical sterilization = ehtylene oxide and other gaseous sterilants |
- inhibits bital cellular functions - sterilization of materials that would be damaged by heat |
|
Plasma sterilization |
- inhibits bital cellular functions - tubular medical instruments - Usually hydrogen peroxide excited in a vacuum by an electromagnetic field. |
|
supercritical fluids |
- inhibits vital celluar functions - sterilizing organic medical implants - carbon dioxide compressed to a supercritical state |
|
peroxygens and other forms of oxygen |
- oxidation - deep wounds - Ozone is widely used as a supplement for chlorination; hydrogen peroxide is a poor antiseptic but a good disinfectant. Peracetic acid is especially effective. |
|
The control of microbial growth can prevent |
infections and food spoilage |
|
Sterilization is the process of |
removing or destroying all microbial life on an object. |
|
Commercial sterilization is heat treatment of |
canned foods to destroy C. botulinum endospores. |
|
Disinfection is the process of |
reducing or inhibiting microbial growth on a nonliving surface. |
|
Antisepsis is the process of |
reducing or inhibiting microorganisms on living tissue. |
|
The suffix -cide means to_______; the suffix -stat means to inhibit. |
-cide = kill |
|
Sepsis is |
bacterial contamination. |
|
Bacterial populations subjected to _____________ usually die at a constant rate |
heat or antimicrobial chemicals u |
|
Such a death curve, when plotted logarithmically, shows this constant death rate as |
a straight line. |
|
The time it takes to kill a microbial population is proportional to |
the number of microbes. |
|
__________ have different susceptibilities to physical and chemical controls. |
Microbial species and life cycle phases (e.g., endospores) |
|
_________may interfere with heat treatments and chemical control agents. |
Organic matter |
|
Longer exposure to lower heat can produce the same effect as |
shorter time at higher heat. |
|
The susceptibility of the plasma membrane is due to its |
lipid and protein components. |
|
Certain chemical control agents damage the plasma membrane by altering its |
permeability. |
|
Some microbial control agents damage cellular proteins by |
breaking hydrogen bonds and covalent bonds. |
|
Heat is frequently used to |
kill microorganisms. |
|
Moist heat kills microbes by |
denaturing enzymes. |
|
__________is the lowest temperature at which all the microbes in a liquid culture will be killed in 10 minutes. |
Thermal death point (TDP) |
|
___________is the length of time required to kill all bacteria in a liquid culture at a given temperature. |
Thermal death time (TDT) |
|
___________is the length of time in which 90% of a bacterial population will be killed at a given temperature. |
Decimal reduction time (DRT) |
|
Boiling (100°C) kills many vegetative cells and viruses within |
10 minutes. |
|
_________is the most effective method of moist heat sterilization. The steam must directly contact the material to be sterilized. |
Autoclaving (steam under pressure) |
|
In ___________, a high temperature is used for a short time (72°C for 15 seconds) to destroy pathogens without altering the flavor of the food. |
HTST pasteurization |
|
____________ (140°C for 4 seconds) is used to sterilize dairy products. |
Ultra-high-temperature (UHT) treatment |
|
Methods of dry heat sterilization include |
direct flaming, incineration, and hot-air sterilization. Dry heat kills by oxidation. |
|
Different methods that produce the same effect (reduction in microbial growth) are called |
equivalent treatments. |
|
Filtration is the |
passage of a liquid or gas through a filter with pores small enough to retain microbes. |
|
Microbes can be removed from air by |
high-efficiency particulate air (HEPA) filters. |
|
Membrane filters composed of cellulose esters are commonly used to filter out |
bacteria, viruses, and even large proteins. |
|
Most microorganisms do not reproduce at ordinary refrigerator temperatures (0–7°C). - Many microbes survive (but do not grow) at the subzero temperatures used to store foods. |
ya |
|
High pressure denatures proteins in |
vegetative cells. |
|
In the absence of water, |
microorganisms cannot grow but can remain viable. |
|
__________ can resist desiccation. |
Viruses and endospores |
|
Microorganisms in high concentrations of salts and sugars undergo |
plasmolysis. |
|
Molds and yeasts are more capable than bacteria of growing in materials with |
low moisture or high osmotic pressure. |
|
The effects of radiation depend on its |
wavelength, intensity, and duration. |
|
___________ (gamma rays, X rays, and high-energy electron beams) has a high degree of penetration and exerts its effect primarily by ionizing water and forming highly reactive hydroxyl radicals. |
Ionizing radiation |
|
_____________, a form of nonionizing radiation, has a low degree of penetration and causes cell damage by making thymine dimers in DNA that interfere with DNA replication; the most effective germicidal wavelength is 260 nm. |
Ultraviolet (UV) radiation |
|
Microwaves can kill microbes indirectly as materials get hot. |
ya |
|
Chemical agents are used on living tissue (as ___________) and on inanimate objects (as __________). |
living tissue (as antiseptics) and on inanimate objects (as disinfectants). |
|
Few chemical agents achieve sterility. |
ya |
|
The presence of organic matter, degree of contact with microorganisms, and temperature should also be considered. |
in disinfection |
|
in the ______________ test, bacterial survival in the manufacturer’srecommended dilution of a disinfectant is determined. |
In the use-dilution test -Viruses, endospore-forming bacteria, mycobacteria, and fungi can also be used in the use-dilution test. |
|
In the __________ method, a disk of filter paper is soaked with a chemical and placed on an inoculated agar plate; a zone of inhibition indicates effectiveness. |
disk-diffusion method |
|
Phenolics exert their action by |
injuring plasma membranes. |
|
__________such as triclosan (over the counter) and hexachloro- phene (prescription) are widely used in household products. |
Bisphenols |
|
Biguanides damage |
plasma membranes of vegetative cells |
|
Some____________ are used alone or as components of inorganic or organic solutions. |
halogens (iodine and chlorine) |
|
Iodine may combine with certain amino acids to |
inactivate enzymes and other cellular proteins. |
|
Iodine is available as a tincture (___________) or as an iodophor (____________). |
tincture (in solution with alcohol) or as an iodophor (combined with an organic molecule). |
|
The germicidal action of chlorine is based on the formation of |
hypochlorous acid when chlorine is added to water. |
|
Alcohols exert their action by |
denaturing proteins and dissolving lipids. |
|
In tinctures, alcohols enhance the |
effectiveness of other antimicrobial chemicals. |
|
Aqueous ethanol (60–95%) and isopropanol are used as |
disinfectants. |
|
Silver, mercury, copper, and zinc exert their antimicrobial action through |
oligodynamic action. When heavy metal ions combine with sulfhydryl (—SH) groups, proteins are denatured. |
|
________have limited germicidal action but assist in removing microorganisms. |
Soaps |
|
Acid-anionic detergents are used to |
clean dairy equipment. |
|
_________ are cationic detergents attached to NH4+. |
Quats |
|
By disrupting plasma membranes, quats allow |
cytoplasmic constituents to leak out of the cell. |
|
Quats are most effective against |
gram-positive bacteria. |
|
SO2, sorbic acid, benzoic acid, and propionic acid inhibit |
fungal metabolism and are used as food preservatives. |
|
Nitrate and nitrite salts prevent |
germination of C. botulinum endospores in meats. |
|
Nisin and natamycin are antibiotics used to |
preserve foods, especially cheese. |
|
Aldehydes such as formaldehyde and glutaraldehyde are among the most effective |
chemical disinfectants. They exert their antimicrobial effect by inactivating proteins. |
|
Ethylene oxide is the gas most frequently used for |
sterilization. - It penetrates most materials and kills all microorganisms by protein denaturation. |
|
Free radicals in plasma gases are used to |
sterilize plastic instruments. |
|
Supercritical fluids, which have properties of ____________, can sterilize at low temperatures. |
liquid and gas, can sterilize at low temperatures. |
|
Hydrogen peroxide, peracetic acid, benzoyl peroxide, and ozone exert their antimicrobial effect by |
oxidizing molecules inside cells. |
|
Gram________ bacteria are generally more resistant than gram __________ bacteria to disinfectants and antiseptics. |
-negative are more resistant that -positive bacteria to disinfectants and antiseptics |
|
Mycobacteria, endospores, and protozoan cysts and oocysts are |
very resistant to disinfectants and antiseptics. |
|
_________ viruses are generally more resistant than __________ viruses to disinfectants and antiseptics. |
Nonenveloped viruses are more resistant than enveloped viurses to disinfectants and antiseptics |
|
Prions are resistant to |
disinfection and autoclaving. |
|
Which of the following is most effective for sterilizing mattresses and plastic Petri dishes? a. chlorine b. ethylene oxide c. glutaraldehyde d. autoclaving e. nonionizing radiation |
b. ethylene oxide |
|
Which of these disinfectants does not act by disrupting the plasma membrane? a. phenolics b. phenol c. quats d. halogens e. biguanides |
d. halogens |
|
Which of the following cannot be used to sterilize a heat-labile solution stored in a plastic container? a. gamma radiation b. ethylene oxide c. supercritical fluids d. autoclaving e. short-wavelength radiation |
d. autoclaving |
|
Which of the following is used to control microbial growth in foods? a. organic acids b. alcohols c. aldehydes d. heavy metals e. all of the above |
a. organic acids |
|
Which disinfectant is the most effective? |
a |
|
Which disinfectant(s) is (are) bactericidal? a. A, B, C, and D b. A, C, and D c. A only d. B only e. none of the above |
b. A, C, and D |
|
Which of the following is not a characteristic of quaternaryammonium compounds? a. bactericidal against gram-positive bacteria b. sporicidal c. amoebicidal d. fungicidal e. kills enveloped viruses |
b. sporicidal |
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A classmate is trying to determine how a disinfectant might kill cells. You observed that when he spilled the disinfectant in your reduced litmus milk, the litmus turned blue again. You suggest to your classmate that a. the disinfectant might inhibit cell wall synthesis. b. the disinfectant might oxidize molecules. c. the disinfectant might inhibit protein synthesis. d. the disinfectant might denature proteins. e. he take his work away from yours. |
b. the disinfectant might oxidize molecules. |
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Which of the following is most likely to be bactericidal? a. membrane filtration b. ionizing radiation c. lyophilization(freeze-drying) d. deep-freezing e. all of the above |
b. ionizing radiation |
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Variables that affect determination of the thermal death point are |
■ The innate heat resistance of the strain of bacteria ■ The past history of the culture, whether it was freeze-dried, wetted, etc. ■ The clumping of the cells during the test ■ The amount of water present ■ The organic matter present ■ Media and incubation temperature used to determine viability of the culture after heating |
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which of the following does not kill endospores? a. autoclaving b. incineration c. hot-air sterilization d. pasteurization e. All of the above killendospores. |
d. pasteurization |
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Ig |
Immunoglobulin |
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IgG vs IgM |
heavy chains are different |
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IgG is |
serious - 80% of your protection - cross placenta - gamma chain |
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IgM |
first antibodies made - mu chain |
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IgA |
- alpha chain |
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IgE |
built like normal monomer - epsilon chain - involved in allergies |
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IgD |
- delta chain |
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- variable region (ends) where |
binds with antigen |
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b cell makes |
makes antibody |
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helper t cell |
defined by presence of antigen CD4 on their membranes - cd4 picks up information and sends it to interleuken |
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Tc (CD8) |
cytotokic t cells - when they find target the produce emzyme that kills cell membrane causes cell lysis |
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antigen presenting cells (APC) |
- dentric cells - macrophages - when cell injests nd then digest then bacterial antigen is now on its surface, can then be recognized by helper t cell |
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T independent antigen |
interferes with b cell without t cell involvement |
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T dependent antigen |
depends on t cells to interfere with b cells |
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antibody coated cells are targeted by |
cytotoxic cells |
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b memory cells |
formed within germinal centers following primary infection and are important in generating an accelerated and more robust antibody-mediated immune response in the case of re-infection - secondary immune response - naturally acquired active immunity |
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artificially acquired active immunity |
vaccination |
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artificially acquired passive immunity |
injection of antibodies - lasts short period of time, but is immediate treatment - not made in body |
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pasteur |
injected rabies in horse and isolated the serum - required daily injections for 14-21 days (small doses) |
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naturally acquire passive |
across the placenta IgG antibodies transfered - dont last longer than 6 months because they are proteins that you dont make |
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using antibodies |
- to identify bacteria and viruses (direct) (if bacterium and antibodies will combine and will agglutinate) - to test for pregnancy (presence of HCG) |
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boosters are composed of |
antigens |
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serotype |
a distinct variation within a species of bacteria or virus or among immune cells of different individuals. |
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fetus produces hormone called |
HCG prevents shedding of uterine lining prevents menstruation - injecting with HCG is fertility drug - pregnancy strip is antiHCG |
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if antigens are produced |
have the antibodies either because they are currently infected, had it and made antibodies, or got vaccinated
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seroconvert |
negative then positive - got infection |
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if titer increases |
it means you have an active infection |
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if titer is consistant |
means you have antibodies present but not infected |
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if igm present |
you have infection because igm are produced first |
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-mab |
monoclonal antibodies |
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why cant you grow eukaryotic cells for long |
bc they have membranes bound organelles |
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monoclonal antibodies |
immunotoxins: MAB conjugated with a toxin to target cancer cells - chimeric MABs: genetically modified mice that produce Ab with a human constant region - humanized MABs: MABs that are mostly human except for mouse antigen binding - fully humanized MABS |