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Chapter 11 & 12
| Term | Definition |
|---|---|
| Four possible outcomes of microbial control outside the body | sterilization, disinfection, antisepsis, decontamination |
| Sterilization | the destruction of all microbial life |
| Bacterial endospores | considered the most resistant microbial entitles destruction of endospores is the goal of sterilization |
| Germicide and microbicide | chemical agents that kill microorganism |
| Antisepsis (degermation) | destroys most microbial life reducing contamination on a living surface |
| Decontamination (sanitization) | the mechanical removal of most microbes from an animate or inanimate surface |
| Bactericide | a chemical that destroys bacteria expect for those in the endospore stage |
| Fungicide | kills fungal spores, hyphae, and yeast |
| Virucide | inactivates viruses, especially on living tissues |
| Sporicide | capable of killing endospores |
| Bacteristatic agents | prevent the growth of bacteria on tissues or objects in the environment |
| Fungistatic agents | inhibit fungal growth |
| Microbistatic agent | chemicals used to control microorganisms in the body |
| Death of microscopic organism | 1.harder to see 2. no conspicuous vital signs 3.lethal agents don't alter the overt appearance of microbial cells 4.loss of movement cant be used to indicate death |
| Factor that affect death rate | 1.number of microorganisms 2.nature of the microbes in the population 3.type of microbial growth 4.temperature and pH of the environment |
| Surfactants | polar molecules with hydrophilic and hydrophobic regions opens up leaky spots |
| Heat | the most widely used method of microbial (others) -radiation -filtration -ultrasonic waves -cold |
| Moist heat | *most effective *hot water, boiling water, steam temp: 60C to 135C *autoclave |
| Moist heat | 121 c temperate 15 minutes (time 2 sterile ) |
| Dry heat | air with low moisture content that has been heated by a flame or electric heating coil temp: 160C to several thousand degree Celsius lack of water increases stability of some protein configurations, necessitation higher temperature |
| Thermal death time | shortest length of time required to kill all test microbes at a specific temperature |
| Thermal death point | lowest temp required to kill all microbes in a sample in 10 min |
| Desiccation | dehydration of vegetative cells directly exposed to normal room air delicate pathogen can be killed by desiccation can preserve food |
| Radiation | energy emitted from atomic activities and dispersed at high velocity through matter or space -gamma rays -X rays -ultraviolet radiation |
| Filtration | an effective method to remove microbes from air and liquids |
| Modes of germicides are to attack cellular targets | -proteins -nucleic acid -cell wall -cell membrane |
| Alcohols as antimicrobial agents | -ethyl and isopropyl alcohol are appropriate 4 microbial control -greater efficacy70% -destroys vegetative microbial forms but not endospores |
| Ethyl alcohol (70%) | skin degerming and disinfection of some types of medical equipment evaporation rate limits effectiveness |
| Hydrogen peroxide (H2O2) | germicidal effects are due to toxic reactive oxygen. bactericidal, virucidal, fungicidal, and sporicidal at high concentrations |
| Applications of Hydrogen peroxide | antiseptic: skin and wound cleansing, bedsore care, mouthwashes disinfectant:soft contacts, surgical implants, plastic equipment sterilization of delicate reusable instruments |
| Surfactants | -limit microbicidal power -varied effects -activity due to amphipathic nature of the molecules -activity reduced by the presence of organic matter |
| Antibiotics | common metabolic products of bacteria and fungi. inhibiting the growth of other microorganisms in the same habitat reduces competition for nutrients |
| Semisynthetic | new drugs are created by chemically altering the structure of naturally occurring antibiotics |
| Synthetic | some natural compounds cant be obtained without the destruction of a habitat or organismal population. drugs created in lab mimic the action of these natural compounds |
| Three factors that have to be known before starting antimicrobial therapy | identify of the microorganism causing the infection. degree of the microorganism's sensitivity to various drugs. overall medical condition of the patient |
| Kirby-Bauer technique | the surface of a plate of special medium is spread with test bacterium. antibiogram : profile of antimicrobial sensitivity |
| Treatment fails because | the inability of the drug to diffuse into that body compartment (brain, joint, skin). resistant microbes in the infection that didn't make it into the sample collected for testing. an infection caused by more that one pathogen (mixed), resistant to drug |
| Therapeutic index (TI) | ratio of the dose the drug that is toxic to humans to its minimum effective (therapeutic) dose. closer these figures are to each other (the smaller the ratio), the greater potential for toxic drug reactions. TI of 1.1 is risker choice than a TI of 10 |
| Choosing an antimicrobial drug | -golden ages on antibiotics ushered in a drastic reduction infectious disease mortality in the 20th century -sometimes older can be better then newer medicine |
| Selective toxicity | -central concept in antibiotic treatment. -antimicrobial drugs should kill or inhibit microbial cells without -simultaneously damaging host tissues. -use current block the actions or synthesis of molecules in microorganisms but not vertebrate cells |
| Penicillin | block the synthesis of the cell wall found only in bacteria |
| Metabolic targets of chemotherapeutic agents | -inhibition of cell wall synthesis - nucleic acid (DNA and RNA) structure and function -protein synthesis, and folic acid synthesis - interference with cell membrane structure or function |
| LOOK UP PENCILLIN G AND V | Table 12.4 |
| Broad spectrum drugs | effective against more than one group of bacteria ex: tetracyclines |
| Narrow spectrum drugs | only target a specific group ex: polymyxin & penicillin |
| Penicillin consist of three parts | thiazolidine ring beta lactam ring variable side chain |
| Aminoglycoside drug | one or more amino sugars and aminocyclitol ring |
| Tetracyclines | natural parent compound and synthetics derivatives. broad spectrum effects. side effects: gastrointestinal disruption, deposition in hard tissues |
| Sulfonamides or sulfa drugs | 1st modern antimicrobial drugs. synthetic: don't originate from bacteria or fungi |
| Fluoroquinolones | high potency broad spectrum absorbed from the intestine side effects: seizures & other brain disturbance |
| Polymyxins | cell membrane derived from Bacillus polymyxa toxic to the kidney |
| Three major modes of action | barring penetration of the virus into the host cell. blocking the transcription and translation of viral molecules. preventing maturation of viral particles |
| Drug Resistance | adaptive response in which microorganisms began to tolerate an amount of drug that would ordinarily |
| Intrinsic | bacteria must be resistant to any antibiotic that they themselves produce |
| Acquired | bacterial resistance to a drug to which they were previously sensitive |
| Resistance (R) factors | plasmids that are transferred through conjugation, transformation, or transduction |
| Drugs in animal feeds | -Nearly 80% of all antibiotics in the US are given to live stock -decreases infections and improves animal health and size -pathogens "jump" to human and cause drug-resistant infections |
| Probiotics | -preparations of live microorganisms fed to animals and humans to improve intestinal biota -replace microbes lost during antimicrobial therapy -ex probiotic yogurts - safe, effective, useful in treating food allergies |
| Prebiotics | nutrients that encourage the growth of beneficial microbes in the intestine |
| Tetracyclines | bind to the enamel of teeth, causing a permanent gray to brown discoloration |
| Superinfection | -beneficial resident species are destroyed through antibiotic therapy. -microbes once small in number begin to overgrow and cause disease |
Created by:
brittanemorris2013