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47 Cards in this Set
- Front
- Back
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Microbial Control |
As microorganisms can cause infection, food spoilage and water contamination, controlling their spread is an ongoing goal of healthcare workers and industry |
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Microbial Control |
Accomplished through 3 approaches: - physical - mechanical - chemical ** most of what we'll see |
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Microbial Control |
Goal is to: - destroy pathogens - remove microorganisms - reduce the number of microbes in a given area |
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Microbial Control |
Type/amount of microbes dealing with and cleaning techniques for equipment determine outcome of control |
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Factors Affecting Antimicrobial Technique |
- material being treated - type of microbe involved - microbial lobe (how much) - time available for the treatment (how often; turnaround time) |
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Definitions |
Sterilization - destruction/removal of all microorganisms and their spores - material treated is considered sterile |
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Definitions |
Disinfection - the destruction of vegetative microorganisms via physical or chemical methods |
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Definitions |
Disinfectant - antimicrobial chemicals specifically designed to be used on nonliving surfaces
Contamination - refers to either the presence of microbes in or on the body, or on objects |
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Definitions |
Contaminant - a substance that is present in an environment where it does not belong or is present at levels that may cause harmful effects to living organisms or the environment |
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Definitions |
Decontamination |
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Definitions |
Antiseptic - ***growth inhibiting*** agent used on tissues to prevent infection - use of such an agent is antisepsis - ex: face wash for acne, alcohol swab before flu shot - cant kill completely because would eat away at skin |
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Definitions |
Bacteriostatic
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Microbial Death Definition |
- the permanent loss of reproductive capability, even under optimum growth conditions
- conditions: nutrients, temperature, atmosphere |
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Microbial Death Definition |
- difficult to define as vital signs are not obvious in microorganisms
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Microbial Death Factors that Affect Death Rate |
- Number of microbes |
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Number and Nature of Microbes |
- more organisms = longer time required to treat equipment
- organisms vary in resistance to physical and
- vegetative cells of bacteria are least resistant |
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Number and Nature of Microbes |
- rapidly dividing cells most susceptible
- some variation in gram-positives and negatives |
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Number and Nature of Microbes Low Resistance Microbes |
- most fungal spores and hyphae - enveloped viruses - yeasts - protozoan trophozoites |
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Number and Nature of Microbes Moderate Resistance Microbes |
- Protozoan cysts - Fungal sexual spores - Some viruses - Some bacterial vegetative cells |
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Number and Nature of Microbes Most Resistant Microbes |
- endospores - prions
- destruction of bacterial endospores used as an indicator of sterilization
- in most circumstances, population is a mixture of microorganisms (target highest res.) |
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Temperature |
- higher temperatures require a shorter period of time for sterilization
- temperature is only effective when use in appropriate range for chemical |
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Temperature |
- dry heat procedures need higher temperatures than methods which use moist heat (dry heat not as effective as moist heat)
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pH |
Optimal pH range where chemicals function best - effectiveness of agent will be reduced outside range
- may increase the amount of agent entering the cell |
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Concentration |
- must ensure concentration appropriate for the
- concentration reduced when extraneous organic matter is present (dilute)
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Presence of Organic Matter, Solvents, and Inhibitors |
Certain substances inhibit the actions of disinfectants and even of heat
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Presence of Organic Matter, Solvents, and Inhibitors |
Effects of extraneous organic matter: - neutralization of agent - reduce agent's concentration - provide shelter to microbes from physical and chemical methods (hiding place) |
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Mode of Action |
Mode/mechanism of action
- cell wall - cell membrane - cellular synthetic processes (DNA, RNA) - proteins |
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Cell Wall |
Agents can damage the cell wall by: - blocking cell wall synthesis - digesting the cell wall (almost like a chemical enzyme) - breaking down the surface
Cells become fragile and can lyse very easily |
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Cell Wall |
Cell wall not the outermost layerbut helps assume shape - if disrupting, make it more fragile and therefore more likely to lyse or be destroyed
mycoplasma - lacking cell wall |
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Cell Wall |
Agents that disrupt the cell wall: - penicillin class of antibiotics - detergents - alcohols
- LPS particularly susceptible |
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Cell Membrane |
With a disruption in the cell membrane, the cell
- loss of vital molecules - entry of damaging chemicals - cell death |
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Surfactant |
- a surface-active agent that forms a water-soluble interface
- can cause cell death when used as cleaning agent |
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Surfactant |
- Works as a microbicidal (killing of microbes) agent by lowering the surface tension of the cell membrane |
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Surfactant |
- Specifically bind to the lipid layer and penetrate the internal hydrophobic region of the cell membrane
- leaves openings in cell membrane allowing injury causing chemicals to seep into the cell |
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Cellular Synthetic Process |
Microbial life depends on a continuous supply of proteins to function as enzymes and structural molecules
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Cellular Synthetic Process |
Agents can impede DNA replication and transcription or change the genetic code, inhibiting cell growth and reproduction |
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Proteins |
Antimicrobial agents disrupt/denature proteins - native state: the way they should normally be found (allows for attachment to other proteins,nutrients, etc. - like a lock and key) - bonds are broken, causing proteins to unravel and create random, irregular loops and coils |
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Proteins |
Proteins cannot function properly once their - active sites are blocked - interferes with the bonding substrates - change in shape inactivates enzymes |
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Material and Equipment Category |
Level of disinfection depends on the invasiveness of the item
- critical items - semi-critical items - non-critical items |
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Critical Items |
- Penetrate skin or mucous membranes
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Critical Items |
Includes: - surgical instruments - cardiac caheters - implants (boobs, heart valves, hip, etc.) - items introduced into the bloodstream or other stile site |
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Semi-Critical Items |
- Items come in contact with mucous membranes but DO NOT penetrate
- Non-invasive instruments
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Semi-Critical Items |
Endoscopes - bronchoscopes, colonscopes, etc.
Endotracheal tubes |
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Semi-Critical Items |
Some thermometers (oral, ear) - vary from semi (rectal) to non critical depending on where taking it from (skin temperature is non-critical - not coming in contact with mucous membrane) |
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Non-Critical Items |
Items contact only intact skin
- ex: stethescope, BP cuff, O2 stat probe |
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Practical Considerations |
- disinfection or steriliztion required?
-what is the likely contaminant?
- object reusable or single-patient use?
- can the item withstand heat, pressure, radiation or chemicals? |
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Practical Considerations |
- Is the method suitable for the application?
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