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Micro ch 6
| Question | Answer |
|---|---|
| Sterilization | removal/destruction of ALL microbes and viruses |
| Aseptic | environment free of pathogens |
| Disinfection/disinfectant | reduction of pathogen content on inanimate objects |
| Antisepsis/antiseptic | reduction of pathogen content on animate objects |
| Degerming | removal of microbes from a surface by scrubbing |
| Sanitization | reduce pathogen count in public places to meet accepted health standards |
| Pasteurization | aim for elimination of pathogens and reduction of numbers of spoilage organisms |
| Historical Pasteurization is __ temp for ___ time | 63°C, 30 min |
| Flash Pasteurization is __ temp for __ time | 72°C, 15 sec |
| Ultrahigh temperature Pasteurization is __ temp for __ time | 134°C, 1 sec |
| Ultrahigh temperature sterilization is __ temp for __ time | 140°C, 1-3 sec |
| -stasis/-static | inhibition of metabolism/growth |
| -cide/-cidal | kills or prevents metabolism/multiplication |
| Germicide | capable of killing microbes, but endospores may survive |
| Sporicide | germicide capable of killing bacterial endospores |
| What are the two categories of Modes of Action of antimicrobial agents? | 1. Target cell walls/membranes 2. Target molecular biology pathways (replication, transcription, translation) |
| Cell wall alteration can cause what in the target cell? | Osmotic lysis |
| What does disruption of an envelope on an enveloped virus do? | Prevents attachment to the next host cell and therefore thwarts an infection. |
| Non-enveloped viruses are _____ resistant to antimicrobial agents than enveloped viruses. | More; their protein capsid can still bind to molecules on the target cells. |
| When an antimicrobial agent interferes with the protein and nucleic acid structure, what happens? | If enough proteins are denatured, the cell dies because there are not enough functional enzymes to carry on metabolism. |
| What are the preferred criteria for the selection of microbial control methods? | inexpensive, fast-acting, stable during storage, control all microbial growth while being harmless to humans, animals, and objects |
| What affects the efficacy of antimicrobial methods? | Nature of the site to be treated, microbes' degree of susceptibility, environmental conditions. |
| List the relative susceptibility of microorganisms from most to least | Enveloped viruses, Gram-positive bacteria, Nonenveloped viruses, Fungi, Gram-negative bacteria, Active-stage protozoa (trophozoites), Cysts of protozoa, Mycobacteria, Bacterial endospores |
| What are the three types of physical methods of control? | Heat, filtration, and radiation |
| What does boiling do? | Kills vegetative cells and some (but not all) endospores. |
| What does autoclaving do? | Coagulates proteins and denatures DNA |
| What is the basic autoclaving settings? | 121°C at 15 psi for 15 min |
| Why shouldn't you use aluminum foil as a covering for something being autoclaved? | The steam doesn't penetrate the foil cover. |
| What are two autoclave efficacy monitors? | Heat-sensitive chemical strips (i.e. tape), Endospore test ampules |
| What are the settings for dry heat antimicrobial measures? | 1 hr at 171°C; 2 hr at 160°C; 16 hr at 121°C |
| How do you measure dry heat effectiveness? | Use Bacillus subtilis spores. |
| Define HEPA | High Efficiency Particulate Air, used for filtration of gases |
| What can't HEPA remove from the air? | Soluble products released from bacteria (i.e. endotoxins/enzymes) |
| What is filtration used for? | Sterilization of solutions of antibiotics, vaccines, liquid vitamins, enzymes, and culture media. |
| What can't filtration remove from solutions? | Dissolved materials, like endotoxins or exotoxins. |
| Pore size 5µm removes _____, ____, ____. | Multicellular algae, animal cells, fungi |
| Pore size 3µm removes ____, ____. | Yeasts, large unicellular algae |
| Pore size 1.2µm removes ____, ____. | Protozoa, small unicellular algae |
| Pore size 0.45µm removes _____. | Largest bacteria |
| Pore size 0.22µm removes ____, ____. | Largest viruses, most bacteria |
| Pore size 0.025µm removes ____, ____. | Larger viruses, pliable bacteria (mycoplasma, some spirochetes) |
| Pore size 0.01µm removes ___. | Smallest viruses |
| Why is a smaller pore than 0.22µm required to effectively catch mycoplasma? | The cells can be 0.1-0.2 µm in diameter (see slide 6.34) |
| Non-ionizing radiation with wavelengths shorter than visible light. | UV light |
| UVA | long wave UV, "black light" - 400nm-315nm |
| UVB | medium wave UV - 315nm-280nm |
| UVC | short wave UV, germicidal UV, 280nm-100nm |
| Exposure to UVC radiation causes what? | direct damage to DNA due to peak absorption by DNA at 254nm |
| UVC is a ____ sterilizer. | bad, ineffective, due to an inability to penetrate well. |
| Name 3 types of ionizing radiations. | Electron beams, gamma rays, X rays. |
| Ionizing radiation has a wavelength of ___? | shorter than 1nm |
| What do ions do? | Disrupt H bonds, oxidize double covalent bonds, and create hydroxide ions, which denature DNA. |
| What is Gamma irradiation used for? | Sterilizing large batches of small-volume items. |
| Sterilant | Type of antimicrobial that kills (or irreversibly inactivates) all bacteria, fungi, protozoa, plant and animal cells, and viruses. |
| Disinfectant | Any chemical agent, used chiefly on inanimate objects, to reduce levels of harmful organisms. |
| Ethylene oxide | Very toxic/dangerous; kills by alkylation of essential chemical groups. |
| Formaldehyde vapor | Carcinogenic, kills by alkylation of essential chemical groups |
| Hydrogen peroxide vapor | Used to sterilize instruments and produces non-toxic products |
| Chlorine dioxide gas | Oxidant that denatures proteins |
| High level disinfectant | kills all pathogens, including endospores |
| Intermediate-level disinfectant | kills fungal spores, protozoan cysts, viruses, pathogenic bacteria |
| Low-level germicide | kills vegetative bacteria, fungi, protozoal trophozoites, some viruses |
| What is high-level disinfectant used for? | To sterilize things that cannot go through autoclaving, i.e. some endoscopes, things with plastic. |
| Name some high-level disinfectants | Gluteraldehyde, Hydrogen peroxide, Peracetic acid, Chlorine dioxide, other chlorine products |
| What is intermediate-level disinfectant used for? | Cleaning things not expected to have endospores, i.e. some endoscopes, vaginal specula, anesthesia breathing circuits (known as semicritical instruments) |
| Name some intermediate level disinfectants | alcohols, iodophor compounds, phenolic compounds |
| What is low-level disinfectant used for? | Cleaning of noncritical items, i.e. blood pressure cuffs, electrocardiogram electrodes for humans, stethoscopes. |
| Name a low-level disinfectant | any quaternary ammonium compound |
| Name some antiseptic agents | Alcohols, Iodophors, Chlorhexidine, Parachlorometaxylenol (for gram positives) |
| Combinations of chlorhexidane and a detergent are highly effective for hand disinfection, marketed under the names _______ or ______. | Hibiclens, Hibiscrub |
| Chlorhexidane is effective against ___________ bacteria. | Gram-positive |
| Aldehydes can be used as a ___-______ disinfectant. | high-level |
| Gluteraldehyde is ____________. | Sporocidal |
| Hydrogen peroxide kills everything (including spores) at ___%-____%. | 10-25% |
| Iodophor | Iodine dissolved in alcohol. |
| Iodine/Iodophors are effective against _____ | Gram-positive, Gram-negative, some spore-forming bacteria, mycobacteria, viruses, fungi. |
| Name some Chlorine antimicrobial agents | Elemental chlorine, Hypochlorous acid, chloramine |
| The active ingredient in bleach is ______ | NaOCL; sodium hypochlorite. |
| Phenols and Phenolics do what? | Denature proteins, disrupt cell membranes. |
| Phenols and Phenolics are effective against... | A lot of things including mycobacteria. Not sporocidal. |
| Phenol was used as a disinfectant first by ____ _____. | Joseph Lister |
| Amphyl | Disinfectant, used for general hospital disinfectant (beds, lamps, etc.) |
| PCMX effective against | Gram-positive organisms, okay against Gram-negative bacteria, mycobacteria, some viruses. |
| Hexachlorophene effective against | Gram-positive bacteria |
| Alcohols are ____-_____ disinfectants. | Intermediate-level |
| What do alcohols do? | Denature proteins, disrupt cell membranes. |
| Why is 70%-90% alcohol more effective than 90-100%? | 90-100% desiccates the cells too quickly; denaturing requires water. |
| Surfactants | "Surface active" chemicals that reduce surface tension of solvents to make them more effective at dissolving solutes. |
| Soaps | Degerming, not antimicrobial |
| Detergents | positively charged organic surfactants |
| Quats | Quaternary ammonium compounds; antimicrobial |
| NH4 | Ammonium (see slide 6.64 for more structures) |
| Phenol coefficient | effectiveness of a disinfectant by comparison to that of phenol (carbolic acid); >1 = better than phenol |
| Use-Dilution test | Most effective disinfectant is the one that works the best at the highest dilution |
| Disk-diffusion method | Paper disk moistened with agent, put on a Muller-Hinton agar plate, then see zone of growth inhibition. |
| In-Use test | Take swabs from equipment before and after disinfection to test for growth. |
| Muller-Hinton agar | Contains beef extract, used in disk-diffusion method. |
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