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Definition of microbial contaminant
Is a microbe that is present at a given place or time, causes infection, spoils food and is undesirable or unwanted.
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Examples of physical agents of controlling microbial growth Physical agents
- heat, cold radiation, drying and filtration. Heat is most common. Moist heat
- denatures proteins and dna while destroying cell membrane can either sterilize
- or disinfect. Dry heat uses higher temperatures usually to incinerate. Also,
- dry ovens. .cold will halt growth (statis), usually used for preservation of
- food or media. radiation affects dna or organelles also known as cold
- sterilization, filtration used on air and liquids. See table on pg. 317.
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Basic kind classification to microbes that would be most resistant to chemical and
physical control.
Highest resistance- prions and bacterial endospores
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Definitions: table 11.2 on page 320 types of chemical controls of microbes
- 4a Decontamination-the destruction, removal, or reduction of undesirable microbes
- 4b Sepsis- The growth of microorganisms in the blood and other tissues
- 4c Asepsis- techniques that prevent the entry of microorganisms into sterile tissue
- 4d Antiseptic- chemicals applied to body surfaces to destroy or inhibit vegetative pathogens
- 4e Disinfection- destruction of vegetative pathogens on inanimate objects
- 4f Sanitation- cleansing technique that removes microorganisms and debris from inanimate surfaces
- 4g Degermation- cleansing technique that removes microorganisms and debris from living tissue
- 4h Sterilization- The removal or destruction of all viable microbes. Almost all
- sterilization done with heat. If chemical used it’s called a sterilants because
- of their ability to destroy spores. Physical methods to sterilize by dry heat,
- moist heat or radiation . Also can use chemical agents such as gas or liquids.
- Mechanical methods of filtration on liquids. Again, see pg 317
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remember
if it ends in cide, it destroys... a germicide aka microbicide is any chemical
agent that kills pathogenic organisms. a bactericide is a chemical that is used
to destroy bacteria except for those in endospore stage . . A fungicide is a
chemical that kills fungi spores, yeast and hyphea. A virucide is any chemical
known to inactivate viruses, especially on living tissue. A sporicide destroys
bacterial endospores.
If it ends in statis or static that means it, makes the microorganisms stand
still. No growth i.e. bacteriostatic. Cold temperatures will do this .. Think
sushi
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What is dry heat? What’s an example of it, some properties of it? Is it more
effective than moist heat.
- Dry heat- air with a low moisture content that has been heated from 160 degrees to sever
- thousand, dry heat kills by dehydrating the cell, removes the water needed for
- metabolism also alters protein structure. High heat will oxidize cells to ash.
- Used on medical waste.
2 methods 1. Incineration. 2. Dry ovens
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What are different ways to killing off endospores?
- 4 ways
- 1. Heat
- 2. Radiation
- 3. Sterilizing gas
- 4. Sporicidal liquid.
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What is the minimum operating condition for a steam autoclave (like min temperature,
time, and pressure)?
15psi……121 degree C …….time 10 min light loads, average 20min, 40 min heavy loads
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Boiling an egg: know things like the definition of thermal death point, thermal
death time, know what they are
Thermal death point-lowest temperature to kill microbes in 10 min
- Thermal death time- shortest length of time to kill microbes at a certain
- temperature.
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Talked about how to things making juices, milk, cheeses, how to make and sterilize and
make this
By pasteurization the process of applying heat to kill bacteria.
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Different types of food you can preserve, like astronaut and military. What type of food
you can use radiation to get rid of germs in/on the foods…
meats. spices and juices
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Surgery rooms, vacuum cleaners: how do you clean the air in these places, what would
you use?
- Filtration, the physical removal of microbes from heat sensitive liquids and circulating
- air.
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When you irradiate food, what does it really do?? What are the benefits of
irradiating your food.
2 types’ ion and Ultraviolet
- Ion is used to kills bacterial pathogens, insects and worms. It helps with
- infection control. It also helps prevent spoilage giving a longer shelf life.
- Used to sterilize medical products.
UV radiation les penetrating and used as a disinfectant .
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What is an antibiotic?
- A chemical substance from one microorganism that can inhibit or kill other
- microbe even minute amounts. May also come from a synthesized compound.
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What are broad-spectrum drugs?
- Treats a large range of bacteria i.e. Tetracycline work on gram - and gram + greatest range of activity Target cell components common to most pathogens
- (ribosome’s)
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What are narrow spectrum drugs?
- effective on a small range of microbes
- Target a specific cell component that is found only in certain microbes.
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Semi synthetic, or synthetic drug? What does this mean
- Synthetic drugs result from the use of chemicals to synthesize antimicrobial compounds in
- the laboratory.
- semi synthetic- isolated from natural sources.. when you manipulate molecules
- by adding or replacing function groups. Leads to a more broad-spectrum use.
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Shotgun approach to anti-microbial therapy, what does this mean in your book?
- it’s administering broad-spectrum drugs instead of narrow to specifically target the
- infection
- Can lead to increase bacteria resistance to drugs.
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What are some of the criteria that would influence person’s decision towards
prescribing certain type of anti-microbial medications to patients? (Like
allergies, pregnancies, etc…)
- the nature of the infection, microbes sensitivity to available drugs, and overall
- status of the infected host
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Characteristics and qualities of antimicrobial drugs
Characteristics 1. Chemical composition 2. Source or origin 3. Site of action.
- They are effective against bacteria, but a limited number are effective against
- protozoa, helminthes, fungi, and viruses
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Definition of broad-spectrum drugs?
- Broad-spectrum drugs like tetracycline have greatest range of activity, work on gram +and -
- bacteria , rickettsias and mycoplasams. They affects the cell components I e.
- ribosomes found in all cells and mitochondria.
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What’s a super infection? Like cockroaches..
It’s when microbes become resistant to the drug therapy and are able mass produce
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What are some of the side effects you get from taking too much anti-microbial drugs?
- 1.Organ toxicity
- 2. Allergic reactions.
- 3. Problems resulting from suppression or
- alteration of normal flora. i.e. super infection.
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What allows bacteria to become resistant to our medication?
- Drug resistance, which is an adaptive response in which the microorganisms begin to
- tolerate the amount of drug that would have inhibited them.
- 1. Spontaneous mutation in critical chromosome gene.
- 2. Acquisition of entire new gene or sets of gene via transfer from another species. These mutations confer resistance. Plasmids called resistance R factors are transferred during conjugation,
- transformation or transduction. Specific mechanisms of drug resistance are; the inducement of alternate enzymes can lead to drug inactivity , occurs with new gene
- 2. Permeability or uptake of drug into bacterium is decreased or eliminated, occurs with mutation or new gene
- 3. Binding sites for drug is decrease in number, mutation or new gene
- 4. An affected metabolic pathway is shut down or alternative pathway used. Occurs
- due to mutation.
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When we test for drug testing susceptibility, what are we testing for?
To see if the drug is effective against the infection
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When cells/microbe dying off (microbial death), what’s involved in that?
- 1. Inhibition of cell wall synthesis.
- 2. Breakdown of cell membrane structure or function.
- 3. Inhibition of structure and function of dna, rna.
- 4. Inhibition of protein synthesis
- 5. Blocks key metabolic pathways. This leads to loss of ability to
- reproduce and eventually death.
Polymoxins affect cell membranes.. They mess with the phospholipids
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Penicillin’s and cephalosporin’s, what are they?
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Penicillin’s and cephalosporin’s block synthesis of peptidoglycan, causing the cell wall to
- lyse (burst). They also have a beta-lactum structure that can be synthetically
- altered so broad spectrum and have a similar mode of action. Primarily gram +
- bacteria.
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Cephanamides? What are they?
- Include both natural and semi-synthetic drug . Acts on cells envelope inhibits
- peptidogyclan synthesis , has a broad spectrum use.
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Amioglycocyides, what are they?
- Broad spectrum drugs that inhibit protein synthesis. Isolated from the streptomycin
- bacteria.2 sugar 6 carbons also tetracycline’s
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Ampicillin, amoxicillin, penicillin, what do they have in common?
- They all have been chemically altered with side chains that help them move across
- the outer membrane of gram negative cell walls
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Know the antibiotic/antimicrobial that inhibits wall cell synthesis. 4 of them
- 1. Penicillin’s.
- 2. Cephalosporins
- 3. cycloserine
- 4. vancomycin
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What classification treats TB.
- Amioglycocyides
- I.e. Broad spectrum-Streptomycin – bubonic plague, tularemia, TB
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Which antimicrobial drug does not interfere with protein synthesis?
Sulfa Drugs
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