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44 Cards in this Set
- Front
- Back
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Sterilization |
Completeremoval of all microorganisms (including endospores) and viruses from an objector surface |
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Disinfection |
Reducingthe number of microorganisms on a surface so that the risk of infection isminimized |
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Disinfectant |
Antimicrobial agent that is applied toinanimate objects only |
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Antiseptic |
Antimicrobial agent that can be appliedto living tissue |
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Bactericide |
Antimicrobialagent that kills bacteria (but not necessarily endospores) |
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Fungicide |
Chemical agent that kills fungi |
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Virucide |
Chemical agent that destroys viruses |
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Bacteriostatic agent |
Substancethat inhibits growth of, but does not kill, bacteria |
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Sanitizer |
Antimicrobialagent used to reduce the number of microorganisms on food-handling equipmentand utensils |
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Effectiveness of antimicrobial agents depends on |
1.Number of microorganisms present2.Environmental conditions (temperature,pH, salinity, presence of organic matter or a biofilm)3.Time of exposure 4.Degree of microbial resistance |
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1.Damageto membranes |
Some agents alter membrane permeability,making membranes “leaky” |
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2.Damageto proteins |
Denaturation of proteins can be permanent(bactericidal) or temporary (bacteriostatic) |
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3.Damageto nucleic acids |
Alkylating agents arechemical mutagens that alter nucleic acids; some are carcinogenic (e.g.,formaldehyde) |
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Heat Sterilization |
Denatures proteins |
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Dry Heat |
slower penetration of substances thanmoist heat - Sterilization requires longer exposureand/or higher temperatures - Useful for powders that must remain dry |
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Moist Heat |
quickly penetrates and kills cells - Autoclave: Steam under pressure (15 minutesat 121°C and 15 psi); penetrates well and kills endospores |
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pasturization |
-Reducesnumbers of pathogens and microorganisms that cause spoilage -Highertemperatures allow shorter treatment times equal times: 63°C for 30 min 72°C for 15 sec |
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Sterilization by filtration |
HEPA filters membrane filters |
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HEPA filters |
remove microorganisms >0.3 µm fromgases |
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Membrane filters |
removemicroorganisms >0.22 µm from liquids |
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physical method of inhibiting growth of microorganisms |
Low temperatures,Desiccation, Osmotic pressure |
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Low temperatures |
inhibitenzyme activity and growth -Refrigeration (4°C) -Freezing (−20 to −80°C) |
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Desiccation |
inhibitsenzyme activity and growth -Driedfoods (cereals, dried fruit, beef jerky) -Lyophilization(freeze-drying) |
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Osmotic pressure |
causesplasmolysisin a hypertonic environment -Saltyor sugary foods (ham, sausage, canned fruit, jams) |
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Ionizing radiation |
(Xrays, gamma rays, electron beams) -Ionizes water to release OH• (freeradicals) - Free radicals damage DNA and proteins - Useful for sterilizing pharmaceuticalsand medical and dental supplies (catheters, suture materials, syringes, gloves,etc.) |
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Ultraviolet (UV) radiation |
-Damages DNA by causing the formation of thyminedimers |
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Microwave radiation |
-Kills by heat; only useful for itemscontaining significant amounts of water |
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Disk-DiffusionMethod |
Zones of inhibition on a plateculture show the efficacyof an antimicrobial agent |
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Phenols/Phenolics |
type of disinfectant that Disruptplasma membranes |
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Halogens |
Iodine -Tincture:dissolved in alcohol -Iodophor:combined with organic molecule -Betadine -Alter protein synthesis and membranes |
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Halogen |
Chlorine -Forms hypochlorousacid(HOCl) inwater -Added to water supplies and pools -Oxidizing agent that inhibits enzymaticfunctions |
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Alcohol |
Ethanol,isopropanol (isopropyl alcohol) - Denatureproteins and dissolve lipids |
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Heavy Metals |
Ag, Hg, Cu, etc. -Even very small amounts of these metalscan denature proteins -The metals react with sulfhydryl (–SH)groups in cysteine |
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Surfactants |
soaps and detergents |
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soaps |
Washaway bacteria |
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Detergents |
Affectplasma membrane |
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Anionic detergent |
used to sanitize laundry and dairyequipment |
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Cationic detergent |
quaternary ammonium compounds (quats) -usedto sanitize dishes, and sometimes added to mouthwash |
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Chemical Food Preservatives |
Organicacids,Sodiumnitrite, Antibiotics |
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Organic acids |
-Potassium sorbate,sodium benzoate, and calcium propionate -Inhibit metabolism -Control growth of molds and bacteria infoods and cosmetics |
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Sodium nitrite |
prevents endospore germination in meats(e.g., hot dogs, sausage, ham, and bacon) |
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Antibiotics |
-Nisinand natamycin prevent spoilage of cheeses |
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Aldehydes |
Inactivatenucleic acids and proteins by reacting covalently with functional groups (–NH2,–OH, –COOH, –SH) -Oftenused to sanitize medical equipment |
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Peroxygens |
-Oxidizingagents -Usedprimarily to sterilize or decontaminate surfaces -O3 (ozone),H2O2(hydrogen peroxide) |
