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64 Cards in this Set
- Front
- Back
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Historical microbial control methods |
Salting foods Smoking foods Pickling Drying Exposing food clothing and bedding to sunlight |
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4 possible outcomes of microbial control outside the body |
Sterilization Disinfection Antisepsis Decontamination |
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Sterilization |
Destruction of all microbial life |
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Disinfection |
Destroys most life, reducing contamination on inanimate surfaces |
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Antisepsis |
Also called degermation Kills most but not all microbes, only on a living surface (skin) |
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Decontamination |
Also called sanitization The mechanical removal of most microbes from an animate or inanimate surface |
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More resistant |
Endospores Prions Staph & pseudomonas Protozoan cysts |
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Less resistant |
Enveloped viruses Gram- pos bacteria Fungi Gram- neg bacteria Protozoan trophozoites |
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Bacterial endospores |
The most resistant microbe Destruction of endospores is the goal of sterilization |
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Sterilized products are essential to human well-being |
Surgical instruments Syringes Commercially packaged foods |
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Sepsis |
The growth of microorganisms in blood and other tissues |
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Asepsis |
Any practice that prevents the entry of infectious agents into sterile tissues and prevents infection |
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Bactericide |
Chemical destroys bacteria except for those in the endospore stage |
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Sporicide |
Capable of killing endospores |
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Bacteristatic |
Prevents the growth of bacteria on tissues or objects does not kill |
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Microbistatic agents |
Chemicals used to control microorganisms in the body (antiseptics and antibiotics) |
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Critical medical devices |
Expected to come into contact with sterile tissues |
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Semi critical medical device |
Come into contact with mucosal membranes |
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Noncritical medical device |
Those that do bot touch the patient or are only touching intact skin |
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Factors that effect death rate of microbes |
The number present Type of growth Temp & pH Concentration of the agent Mode of action of the agent Presence of solvents, interfering organic material, or inhibitors |
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Cellular targets of physical and chemical agents |
The cell wall The cell membrane Cellular synthetic processes (DNA, RNA) Proteins |
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Surfactants |
Polar molecules with hydrophillic ans hydrophobic regions Physically bind to the lipid bilayer and penetrate Open up leaky spots that allow injurious chemicals to seep into the cell and important ions leak out |
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Native state |
The normal 3-dimensional shape of a protein that allows proper function |
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Denaturation |
Disruption of a proteins native shape, rendering them nonfunctional |
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Moist heat (denaturation) |
Irreversible solidification of an egg white when boiled/cooked |
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Methods of physical control |
Radiation Filtration Ultrasonic waves Cold |
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Moist heat as an agent of microbial control |
Hot water, boiling water, & steam Ranges from 60 C - 135 C Operates at lower temperatures and shorter exposure times than dry heat |
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Dry heat as an agent of control |
Air with a low moisture content that has been heated by a flame or elastic heating coil Ranges from 160 C + Lack of water increases protein configurations At high temps, dry heat oxidizes cells, burning them to ashes |
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Thermal death time |
The shortest length of time required to kill all test microbes at a specified temp |
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Thermal death point |
The lowest temperature required to kill all microbes in a sample in 10 mins |
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Desiccation |
Dehydration of vegetative cells directly exposed to normal room air Desiccation can kill pathogens or even preserve foods |
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Lyophilization |
Combination of freezing and drying Common method of preserving microbes and other cells in a viable state |
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Radiation |
Energy emitted from atomic activities and dispersed at high velocity through matter or space (Gamma, UV, X-ray) |
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Irradiation |
Bombardment of microbes with radiation |
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Ionizing radiation |
Ejects orbital electrons from an atom, causing ions to form. Causes most damage to proteins |
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Nonionizing radiation |
Excites atoms, raising them to higher energy state Leads to formation of abnormal bonds within DNA |
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Cold sterilization |
Ionizing radiation used as an effective alternative for sterilizing. Used for materials sensitive to heat and chemicals. |
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UV Radiation |
100 nm to 400nm Lethal at ~260 nm Germicidal lamp: 254 nm Not as penetrating as ionizing radiation |
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UV Radiation: non-ionizing effects |
Absorped by DNA Form pyrimidine dimers (Thymine & cytosine) Interfere with dna replication & transcription |
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Antimicrobial chemicals |
Solid Liquid Gaseous Or a mixture of the two |
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Aqueous solutions |
Solutions containing pure water as the solvent |
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Tinctures |
Antimicrobial chemicals dissolved in pure alcohol or water-alcohol mictures |
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Factors affecting the microbial activity of chemicals |
Nature of microbes being treated Nature of material being treated Degree of contamination Time of exposure Strength and chemical action of the germicide |
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Halogens |
Fluorine, Bromine, Chlorine, and Iodine Microbicidal and sporicidal 1/3 of all antimicrobial chemicals |
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Chlorine |
Gaseous chlorine, hypochlorites, and chloramines Kill bacteria, endospores, fungi? & viruses Less effective if exposed to light, alkaline pH, and excessive organic matter |
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Iodine |
Free iodine (I2) & Iodophors All classes of organisms are killed by iodine if proper concentrations and exposure times are used |
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Phenol |
First used as the major antimicrobial chemical Toxic and irritating side effects |
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Phenolics |
Destroy vegetative bacteria, fungi, & some viruses Able to act in the presence of organic matter Too toxic to be used as an antisepsis |
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Alcohols |
Ethyl and isopropyl are the only appropriate microbial control Greater efficacy at 70% More effective against enveloped viruses than naked viruses |
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Hydrogen peroxide |
Germicidal effects are due to toxic reactive oxygen Bactericidal, virucidal, fungicidal, and sporicidal & high concentrations |
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Quaternary ammonium compounds (Quats) |
Disinfectants: mixed with cleaning agents to sanitize a variety of objects/surfaces Preservatives for ophthalmic solutions and cosmetics |
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Perfect antimicrobial therapy |
Soluble in the body Be selective (toxic to microbe nontoxic to the host) Remains potent and active |
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Chemotherapeutic drug |
Any chemical used in the treatment, relief, or prophylaxis of a disease |
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Prophylaxis |
Use of a drug to prevent imminent infection of a person at risk |
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Prophylaxis |
Use of a drug to prevent imminent infection of a person at risk |
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Antimicrobial chemotherapy |
The use of chemotherapeutic drugs to control infection |
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Antimicrobials |
All-inclusive terms for any antimicrobial drug regardless of what type of microorganism it targets |
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Antibiotics |
Substances produced by natural metabolic processes of some microorganisms or scientists that can inhibit or destroy infection |
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Semisynthetic drugs |
Chemically modified in the laboratory after being isolated from natural sources |
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Narrow-spectrum |
Only affects small amount of bacteria |
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Broad-spectrum |
Treats a large number of bacteria all equally |
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Synthetic antibiotic |
Mimicking a drug that is naturally occurring. Completely chemically modified in the lab. |
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3 factors must be known before treatment begins |
-identity of microorganism - the degree of microorganisms sensitivity to drugs - the overall medical condition of the patient |
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Testing for drug susceptibility |
Kirby-bauer technique: Test the bacterium with various antibiotics and observe the zone of inhibition |
