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27 Cards in this Set
- Front
- Back
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What is chemotherapy
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use of chemicals that are effective in treating cancer or selectively kill or inhibit the growth of microorganisms at low concentrations
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What are the two antimicrobial chemotherapy goals (ON EXAM)
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to eliminate a pathogen
prophylaxis |
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What are the five abuses of antimicrobial chemotherapy (ON EXAM)
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-tx of untxable infections
-tx a fever of unknown origin -improper dosage -inappropriate use of chemo alone (w/o I&D) -poor rx selection due to lack of info on bacteria |
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Rank for broadest to most specific
antimicrobials antibiotics anti-infectives |
antiinfective > antimicrobial > antibiotics
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What is the primary use of anti-infective agents
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to kill or inhibit the growth of organisms
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Why can't local anti-infectives be used systemically
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too toxic
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What is an antimicrobial agent used for
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kill/inhibit the growth of microorganisms
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What are the five key characteristics of an ideal antimicrobial (ON EXAM)
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-demonstrates selective toxicity
-does not induce allergic reaction -is not destroyed, neutralized or excreted too rapidly -therapeutic dose at site of infection -pathogens do not develop resistance |
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What is the chemotherapeutic index
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TD50/ED50
-reflects margin of safety -higher number = more safe |
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What does the clinical effectiveness of a drug depend on
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it's maximal efficacy, not its potency
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What are antibiotics
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substances produced by microorganisms that suppress the growth or cause the death of other microorganisms
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which phase is the best time to treat
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log phase - right before bacteria are going to take off
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What is PAE
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post antibiotic effect
- prevents reverse outgrowth |
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What are the four factors that determine whether an antibiotic is cidal or static
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-drugs mechanism of action
-microorganisms state of growth -conc of drug which org is exposed to -type of micro involved and abx specturm of activity |
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What is the MIC
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lowest concentration to prevent growth after 1 day of incubation
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Which spectrum of abx are at lowest risk for superinfections (secondary infections that occur due to imbalance of normal flora)
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narrow spectrum
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How do narrow and extended spectrum differ from broad spectrum
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broad are static, narrow and extended are typically cidal
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What are the two exceptions of narrow/extended drugs being cidal
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clindamycin and nacrolides (both static)
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What are other factors that affect outcome of antimicrobes (4)
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-immune status, age, health
-site of infection -presence of foreign objects -patient compliance |
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What are three ways to achieve selective toxicity
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-drug blocks pathway only organism has
-drug block rxn more vital to microbe than host -drugs blocks pathway to both but only microbe converts drug to active metabolite |
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T/F - some bacteria have constitutive resistance to a drug
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-true
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What are three ways drugs can have acquired resistance
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-keep drug from reaching it's target
-inactivate drug -alter target |
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What are four genetic mechanisms of acquired resistance
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-mutation of gene
-transduction -transformation -conjugation --> all deal w/transposons |
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What are four indications for combo use of abx
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-severe infection of unknown cause
-polymicrobial infection -enhanced antibacterial activity in tx of specific infection -prevent emergence of resistanct microbes |
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What is synergism
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inhibition of growth by a combo of drugs at less than 25% of MIC for each drug acting alone
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What are three examples of synergistic mechanisms
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-each drug affects a different step in biochemical pathway
-one drug may enhance the uptake of a second drug by microbe -one drug may prevent the enzymatic degradation of another drug |
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What are four disadvantages of combo antimicrobial therapy
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`-one agent may enhance the toxicity of the other
-expensive -allows to selection of MDR organisms -antagonism |
