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64 Cards in this Set

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Historical microbial control methods

Salting foods


Smoking foods


Pickling


Drying


Exposing food clothing and bedding to sunlight

4 possible outcomes of microbial control outside the body

Sterilization


Disinfection


Antisepsis


Decontamination

Sterilization

Destruction of all microbial life

Disinfection

Destroys most life, reducing contamination on inanimate surfaces

Antisepsis

Also called degermation


Kills most but not all microbes, only on a living surface (skin)

Decontamination

Also called sanitization


The mechanical removal of most microbes from an animate or inanimate surface

More resistant

Endospores


Prions


Staph & pseudomonas


Protozoan cysts

Less resistant

Enveloped viruses


Gram- pos bacteria


Fungi


Gram- neg bacteria


Protozoan trophozoites

Bacterial endospores

The most resistant microbe


Destruction of endospores is the goal of sterilization

Sterilized products are essential to human well-being

Surgical instruments


Syringes


Commercially packaged foods

Sepsis

The growth of microorganisms in blood and other tissues

Asepsis

Any practice that prevents the entry of infectious agents into sterile tissues and prevents infection

Bactericide

Chemical destroys bacteria except for those in the endospore stage

Sporicide

Capable of killing endospores

Bacteristatic

Prevents the growth of bacteria on tissues or objects does not kill

Microbistatic agents

Chemicals used to control microorganisms in the body (antiseptics and antibiotics)

Critical medical devices

Expected to come into contact with sterile tissues

Semi critical medical device

Come into contact with mucosal membranes

Noncritical medical device

Those that do bot touch the patient or are only touching intact skin

Factors that effect death rate of microbes

The number present


Type of growth


Temp & pH


Concentration of the agent


Mode of action of the agent


Presence of solvents, interfering organic material, or inhibitors

Cellular targets of physical and chemical agents

The cell wall


The cell membrane


Cellular synthetic processes (DNA, RNA)


Proteins

Surfactants

Polar molecules with hydrophillic ans hydrophobic regions


Physically bind to the lipid bilayer and penetrate


Open up leaky spots that allow injurious chemicals to seep into the cell and important ions leak out

Native state

The normal 3-dimensional shape of a protein that allows proper function

Denaturation

Disruption of a proteins native shape, rendering them nonfunctional

Moist heat (denaturation)

Irreversible solidification of an egg white when boiled/cooked

Methods of physical control

Radiation


Filtration


Ultrasonic waves


Cold

Moist heat as an agent of microbial control

Hot water, boiling water, & steam


Ranges from 60 C - 135 C


Operates at lower temperatures and shorter exposure times than dry heat

Dry heat as an agent of control

Air with a low moisture content that has been heated by a flame or elastic heating coil


Ranges from 160 C +


Lack of water increases protein configurations


At high temps, dry heat oxidizes cells, burning them to ashes

Thermal death time

The shortest length of time required to kill all test microbes at a specified temp

Thermal death point

The lowest temperature required to kill all microbes in a sample in 10 mins

Desiccation

Dehydration of vegetative cells directly exposed to normal room air


Desiccation can kill pathogens or even preserve foods

Lyophilization

Combination of freezing and drying


Common method of preserving microbes and other cells in a viable state

Radiation

Energy emitted from atomic activities and dispersed at high velocity through matter or space


(Gamma, UV, X-ray)

Irradiation

Bombardment of microbes with radiation

Ionizing radiation

Ejects orbital electrons from an atom, causing ions to form. Causes most damage to proteins

Nonionizing radiation

Excites atoms, raising them to higher energy state


Leads to formation of abnormal bonds within DNA

Cold sterilization

Ionizing radiation used as an effective alternative for sterilizing.


Used for materials sensitive to heat and chemicals.

UV Radiation

100 nm to 400nm


Lethal at ~260 nm


Germicidal lamp: 254 nm


Not as penetrating as ionizing radiation

UV Radiation: non-ionizing effects

Absorped by DNA


Form pyrimidine dimers


(Thymine & cytosine)


Interfere with dna replication & transcription

Antimicrobial chemicals

Solid


Liquid


Gaseous


Or a mixture of the two

Aqueous solutions

Solutions containing pure water as the solvent

Tinctures

Antimicrobial chemicals dissolved in pure alcohol or water-alcohol mictures

Factors affecting the microbial activity of chemicals

Nature of microbes being treated


Nature of material being treated


Degree of contamination


Time of exposure


Strength and chemical action of the germicide

Halogens

Fluorine, Bromine, Chlorine, and Iodine


Microbicidal and sporicidal


1/3 of all antimicrobial chemicals

Chlorine

Gaseous chlorine, hypochlorites, and chloramines


Kill bacteria, endospores, fungi? & viruses


Less effective if exposed to light, alkaline pH, and excessive organic matter

Iodine

Free iodine (I2) & Iodophors


All classes of organisms are killed by iodine if proper concentrations and exposure times are used

Phenol

First used as the major antimicrobial chemical


Toxic and irritating side effects

Phenolics

Destroy vegetative bacteria, fungi, & some viruses


Able to act in the presence of organic matter


Too toxic to be used as an antisepsis

Alcohols

Ethyl and isopropyl are the only appropriate microbial control


Greater efficacy at 70%


More effective against enveloped viruses than naked viruses

Hydrogen peroxide

Germicidal effects are due to toxic reactive oxygen


Bactericidal, virucidal, fungicidal, and sporicidal & high concentrations

Quaternary ammonium compounds (Quats)

Disinfectants: mixed with cleaning agents to sanitize a variety of objects/surfaces


Preservatives for ophthalmic solutions and cosmetics

Perfect antimicrobial therapy

Soluble in the body


Be selective (toxic to microbe nontoxic to the host)


Remains potent and active

Chemotherapeutic drug

Any chemical used in the treatment, relief, or prophylaxis of a disease

Prophylaxis

Use of a drug to prevent imminent infection of a person at risk

Prophylaxis

Use of a drug to prevent imminent infection of a person at risk

Antimicrobial chemotherapy

The use of chemotherapeutic drugs to control infection

Antimicrobials

All-inclusive terms for any antimicrobial drug regardless of what type of microorganism it targets

Antibiotics

Substances produced by natural metabolic processes of some microorganisms or scientists that can inhibit or destroy infection

Semisynthetic drugs

Chemically modified in the laboratory after being isolated from natural sources

Narrow-spectrum

Only affects small amount of bacteria

Broad-spectrum

Treats a large number of bacteria all equally

Synthetic antibiotic

Mimicking a drug that is naturally occurring. Completely chemically modified in the lab.

3 factors must be known before treatment begins

-identity of microorganism


- the degree of microorganisms sensitivity to drugs


- the overall medical condition of the patient

Testing for drug susceptibility

Kirby-bauer technique:


Test the bacterium with various antibiotics and observe the zone of inhibition