micro ch 9
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42 terms
Terms | Definitions |
|---|---|
 Antimicrobials that kill | germicides, bactericides, fungicides, virucides, sporicides |
| Antimicrobials that inhibit microbial growth/reproduction | microbistatic, bacteriostatic, fungalstatic, etc. |
| Disinfectant | Antimicrobial agent used to destory pathogenic nonsporulating bacteria or their toxins on inanimate objects. that is they are bactericidal. |
| germicide or microbicide | any chemical agent used to kill pathogenic organisms, some can be used (safely) on living tissue of they can be used on inanimates. |
| Antiseptic | antimicrobial agent that inhibits or kills infectious microbial growth in vivo. they tend to be more bacteriostatic than bactericidal & are sufficientlt non-toxic to allow application to skin & mucous membranes. |
| Sanitizer | a compound such as soap or detergent which is used to remove microbes and food. |
| Degermer | an agent of removing microbes from the human skin |
| Factors that affect Death rate | -number of microbes -nature of microbes in the population -temperature and PH of enviroments -concentration or dosage of agent -mode of action of the agent -persence of solvents, organic matter, or inhibitors |
| Antimicrobial Agents' modes of action | 1. the effects of agents on the cell wall 2. how agents affect the cell membrane: surfactants 3. agents affecting nucleic acid synthesis and protein synthesis 4. agents that alter protein function: denaturing 5. antimetabolites: inhibits the utilization of a metabolites necessary for growth |
| Methods of physical control | 1. heat-moist and dry 2. cold temperatures 3. desiccation 4. radiation 5. filtration |
| Moist heat | lower temperatures and shorter exposure time; coagulation and denaturation and proteins |
| Dry heat | moderate to high temperatures; dehydration, alters protein structure; incinceration |
| TDT- Thermal death time | shortest length of time required to kill all test microbes at a specified temperature |
| TDP- Thermal death point | lowest temperature required to kill all microbes in a sample in 10 minutes |
| Pasteurization | heat is applied to kill potential agents of infection and spoilage without destroying the food flavor or value (batch/flash) |
| Microbiostatic | slows the growth of microbes; used to preserve food, media, and cultures |
| Dessication | gradual removal of water from cells, leads to metabolic inhibition |
| Lyophilization | freeze drying; preservation |
| Ionizing radiation | Deep penetrating power that has sufficient energy to cause electrons to leave their orbit, breaks DNA; gamma rays, X-rays, cathode rays; preserving food |
| Nonionizing radiation | Little penetrating power so it must be directly exposed; UV light creates pyrimidine dimers, which interfere with replication; sterilizing air, water or surfaces |
| Desirable qualities of chemicals | -rapid action in low concentration -solubility in water or alcohol, stable -broad spectrum, low toxicity -penetrating -noncorrosive and nonstaining -affordable and readily available |
| High-level germicides | kill endospores; may be sterilants |
| Intermediate-level germicides | kill fungal spores (not endospores), tubercle bacillus, and viruses |
| Low-level germicides | eliminate only vegetative bacteria, vegetative fungal cells, and some viruses |
| Factors that affect germicidal activity of chemicals | -nature of the material being treated -degree of contamination -time of exposure -strength and chemical action of the germicide |
| Chlorine, hypochlorites (chlorine bleach), chloramines | -Denatuate proteins by disrupting disulfide bonds -intermediate level -unstable in sunlight, inactivated by organic matter -water, sewage, wastewater, inanimate objects |
| Iodine, iodophors (betadine) | -interferes with disulfide bonds of proteins -intermediate level -milder medical and dental degreming agents, disinfectants, ointments |
| Phenolics | -disrupt cell walls and membranes and precipiate proteins -low to intermediate level -bactericidal, fungicidal, virucidal, not sporicidal |
| Alcohols | -acts as surfactants dissolving membrane lipids and coagulating proteins of vegetative bacterial cells and fungi -intermediate level |
| Hydrogen Peroxide | -produces highly reactive hydroxyl-free radicals that damage protein and DNA while also decomposing to 0(2) gas- toxic to anaerobes -anticeptic at low concentrations; strong solutions are sporicidal |
| Aldehydes | -kill by alkylating protein and DNA --glutaraldehyde and formaldehyde |
| Glutaraldehyde | 2%(Cidex) used as sterilant for heat sensitive instruments -high-level |
| Formaldehyde | disinfectant, preservative, toxicity limits use -intermediate to high level |
| Gases and Aerosols | -Ethylene oxide -strong alkylating agents -high-level -sterilize and disinfect plastics and prepackaged devices, foods |
| Quaternary Ammonia compounds (quats) | -acts as surfactants that alter membrane permeability of some bacteria and fungi -very low-level -effective against some gram(+) bacteria, most viruses, fungi, and algae -ineffective against tuberculosis bacterium, bacillus, hepatitis virus, spores and any concentration, and gram(-) bacteria |
| Detergents and Soaps | mechanically remove soil and grease containing microbes |
| Heavy Metals | -solutions of silver and mercury kill vegetative cells in low concentrations by inactivating proteins -oligodynamic action -low-level Merthiolate, silver, nitrate, silver |
| Dyes | -very active against gram(+) species od bacteria and various fungi -sometimes used for antisepsis and wound treatment -low-level -narrow spectrum of activity |
| Acids and Alkalis | low level of activity -organic-prevent spore germination and bacterial and fungal growth -acetic-inhibits bacterial growth -propinonic- retards molds -lactic- prevents anaerobic bacterial growth -benzoic and sorbic- inhibits yeast |
| High resistance | prions, bacterial endospores |
| Moderate resistance | pseudomonas sp., mycobacterium tuberculosis, staphylococcus aureus, protozean cysts |
| Least resistance | most bac. veg cells, fungal spores and hyphae, yeast, enveloped viruses, protozan trophzite |
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