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Micro CH11
| Question | Answer |
|---|---|
| What are the 3 categories of resistance in microbial control? | High Resistance, Moderate Resistance, Low Resistance |
| Define High Resistance. | Very difficult to control (Endospores) |
| Define Moderate Resistance | More difficult than most organisms to control, but not as hard as bacterial endospores (Protozoan Cysts, Naked Viruses, Fungal Spores). |
| Define Low Resistance | Relatively easy to control (Most vegetative bacteria, Fungal Hyphae, Enveloped Viruses[Disrupt envelope, therefore they are unable to attach] |
| What are several factors that affect Microbial Death Rate? | Numbers of Microbes present Relative resistance of microbes Temperature/PH of Environment Concentration and/or dosage of controlling agent |
| What is a major factor to consider when assessing Microbial Resistance? | Do they produce endospores? (High Resistance) |
| Why does the number of microbes present affect microbial death rate? | More microbes = more difficult to control |
| How does the temperature/PH affect microbial death rate? | Increased Temp = Biocidal (Killing) Decreased Temp = Biostatic (Holding Steady) Sometimes @ high heat the killing agent is removed too quickly. |
| How does the concentration/dosage of a controlling agent affect microbial death rate? | More agent = better to kill bacteria **Exceptions - Bleach and ethanol |
| What are several antimicrobial agents' modes of action? | Affect the cell wall Affect the cell membrane Affect Protein and Nucleic Acid synthesis Affect/alter protein structure and function |
| What effects can be seen on the cell wall in microbial control? | The cell wall becomes fragile and lyses (cell wall ruptures) |
| What effects can be seen on the cell membrane in microbial control? | The membrane loses integrity. |
| What effects can be seen on protein and nucleic acid synthesis in microbial control? | prevention of replication, transcription, translation, peptide bond formation, protein synthesis |
| What effects can be seen in Protein structure and function alterations in microbial control? | Disruption or denaturation (change its shape/composition) of the protein |
| What are 2 physical methods of microbial control? | Heat and Radiation |
| What are 2 types of microbial control in reference to controlling with heat? | Moist and Dry Heat |
| What occurs when using moist heat? | Organisms are exposed to lower temperatures for a shorter exposure time, denaturation and coagulation of proteins occur |
| What occurs when using dry heat? | Organisms are exposed to moderate to high heat (burning/incineration), dehydration occurs, protein structure is altered |
| Name some moist heat methods. | Steam under pressure, Autoclaving, Tyndallization, Boiling Water, Pasteurization |
| Steam under pressure (autoclaving) would be considered a form of what? | Sterilization |
| Boiling water and tyndallization are both considered methods of what? | Disinfection |
| How long and at what temperature should the boiling water method be done? | 100 degrees for 30 minutes (destroys non-spore-forming pathogens) |
| Pasteurization is not considered a form of what? | Sterilization. It only kills non-spore-forming pathogens and lowers the overall microbe count |
| Name dry heat methods of microbial control | Incineration and dry ovens |
| Name cold methods of microbial control. | Microbiostatic - Slows the growth of microbes Microbiocidal - Kills microbes Refrigeration - 0-15 degrees Celcius Freezing - less than 0 degrees Celcius |
| Lyophilization | A method of preservation using the process of freeze drying |
| Name two types of microbial control by way of radiation. | Ionizing radiation and nonionizing radiation |
| Describe ionizing radiation. | deep penetrating power that has sufficient energy to cause electrons to leave their orbit, breaks DNA |
| Describe nonionizing radiation. | little penetrating power so it must be directly exposed |
| Name an example of nonionizing radiation. | Ultraviolet rays (Interfere with replication) |
| Name some examples of ionizing radiation. | Gamma Rays, X Rays, Cathode Rays (Used to sterilize medical supplies and food products) |
| Define Filtration. | Physical removal of microbes by passing a gas or liquid through a filter |
| Describe a liquid filter. | Different size pores remove different contaminants. |
| Give an example of an air/gas filter. | HEPA filter |
| Name some desirable qualities of chemicals in respect to chemical agents in microbial control. | Rapid action in low concentration, solubility in h2o or alcohol (stable), Broad Spectrum with low toxicity, penetrating, noncorrosive, nonstaining, affordable and readily available |
| What are high level germicides used for and what do they kill? | Devices that are not heat sterilizable and intended to be used in sterile environments (body tissue). They kill endospores and may be strilants. |
| What are intermediate level germicides used for and what do they kill? | Used to disinfect devices that will come in contact with mucous membranes but are not invasive. They kill fungal spores (not endospores), tubercle bacillus, and viruses. |
| What are low level germicides used for and what do they kill? | Clean surfaces that touch skin but not mucous membranes. They eliminate only vegetative bacteria, vegetative fungal cells and some viruses. |
| Name factors that affect germicidal activities of chemicals. | Nature of the material being treated, Degree of contamination, Time of exposure, Strength and chemical action of the germicide |
| Name the Halogen Antimicrobial Chemicals. | Chlorine, Hypochlorites (Chlorine Bleach), Iodine, iodophors (betadine) |
| Halogens would be classified as what level germicide? | Intermediate Level |
| Name some phenolics. | Lysol, Triclosan (antibacterial additive to soaps), Chlorhexidine |
| Phenolics would be classified as what level germicide? | Low to intermediate. |
| How do alcohols work? | Act as surfactants dissolving membrane lipids and coagulating proteins of vegetative bacterial cells and fungi |
| Alcohols would be classified as what level germicide? | Intermediate. |
| How do hydrogen peroxides work? | Produce highly reactive hydroxyl-free radicals that damage protein and DNA while also decomposing to O2 gas – toxic to anaerobes |
| At low concentrations, hydrogen peroxide is used as an ________. | Antiseptic |
| Strong hydrogen peroxide solutions are _____. | Sporicidal |
| Name 2 Aldehydes. | Formaldehyde, Glutaraldehyde |
| How do aldehydes work? | by alkylating protein and DNA |
| Aldehydes would be classified as what level germicide? | Glutaraldehyde - HIGH LEVEL, Formaldehyde - Intermediate to high level |
| Name a gas/aerosol agent. | Ethylene oxide, propylene oxide |
| Gases are classified as what level germicide? | High level |
| Quaternary ammonia compounds (quats) - what do they do? | act as surfactants that alter membrane permeability of some bacteria and fungi |
| QUATS would be classified as what level germicide? | Very Low level |
| How do detergents and soaps work? | They mechanically remove grease and sol containing micobes. |
| Name some heavy metal compounds. | Merthiolate, Silver Nitrate, Silver |
| What level of germicide would heavy metals be classified as? | Low Level |
| Acids and alkalis would have a ______ level in respect to germicide level. | Low Level |
Created by:
wiveys
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