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20 Cards in this Set
- Front
- Back
Define chemotherapy
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The treatment of diseases with antibiotics or other chemical agents
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Define antibiotics
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Antimicrobial agents of microbial origin.
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Define chemotherapeutic agents
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Chemically synthesized antimicrobial agents
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What are the characteristics of antibiotics
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Low molecular weight; specific spectrum of antimicrobial activity (broad or narrow); Exert effects by a specific mechanism
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What are the differences between antibiotics and disinfectants
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Disinfectants are nonspecific with respect to both mechanism of action and spectrum of activity. They are also not tolerated by the host
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What is the basis of selective toxicity
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Absence of the target from the host; permeability differences; structural differences in the target. Also, antimicrobial agents must be effective against bacteria at concentrations that are not deleterious to the host
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What considerations must antibiotic therapy include
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Effect of the drug on the microbe; effect of the microbe on the drug; effect of the microbe on the host; drug-host interactions
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What are bacteriostatic agents
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Growth inhibitory antibiotics. They generally act as competitive inhibitors
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What are bactericidal agents
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Lethal antibiotics, which may or may not involve cell lysis. They are only effective against actively growing cells
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What does plate dilution measure
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The minimal inhibitory concentration. It tests the sensitivities of several isolates to a single concentration of a single antibiotic
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What does Tube dilution measure
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The minimal inhibitory concentration (MIC), as well as the minimal lethal dose (MLD). Tests the sensitivity of a single strain to a range of concentrations of a single antibiotic
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What does disc diffusion measure
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The minimal lethal dose (MLD). Determines the sensitivity of a single strain to a variety of different antibiotics
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What circumstances indicate combined antibiotic therapy
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Chronic infections, to prevent or delay the emergence of resistant organisms; Emergency situations; Mixed infections; To achieve synergistic effects
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What is an indifferent (or additive) response
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The response to a drug combination that is essentially the sum of the two antibiotics being used. The benefit of the second drug is often not clinically significant
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What is an antagonistic antibiotic response
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The combination of two antibiotics is less than the sum of the two independently. Usually caused by interaction of a bactericidal drug (streptomycin) with a bacteriostacic drug (chloramphenicol)
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What does Tube dilution measure
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The minimal inhibitory concentration (MIC), as well as the minimal lethal dose (MLD). Tests the sensitivity of a single strain to a range of concentrations of a single antibiotic
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What does disc diffusion measure
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The minimal lethal dose (MLD). Determines the sensitivity of a single strain to a variety of different antibiotics
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What circumstances indicate combined antibiotic therapy
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Chronic infections, to prevent or delay the emergence of resistant organisms; Emergency situations; Mixed infections; To achieve synergistic effects
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What is an indifferent (or additive) response
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The response to a drug combination that is essentially the sum of the two antibiotics being used. The benefit of the second drug is often not clinically significant
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What is an antagonistic response
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The combination of two antibiotics is less than the sum of the two independently. Usually caused by interaction of a bactericidal drug (streptomycin) with a bacteriostatic drug (chloramphenicol)
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