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30 Cards in this Set
- Front
- Back
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Chemotherapeutic agents |
-chemical agents used to treat disease -destroy pathogenic microbes or inhibit their growth within host -most are antibiotics |
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Antibiotics |
microbial products or their derivatives that kill susceptible microbes or inhibit their growth |
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Paul Ehrlich (1904) |
-developed concept of selective toxicity -identified dyes that effectively treated African sleeping sickness |
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Sahachiro Hato (191) |
working with Ehrlich, identified arsenic compounds that effectively treated syphilis |
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Gerhard Domagk, Jacques, & Therese Trefouel (1935) |
discovered sulfonamides and sulfa drugs |
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Penicillin |
-FIRST discovered by Ernest Duchesne (1896) discovery lost -accidentally discovered by Alexander Fleming 1928 -effectiveness demonstrated by Florey, Chain, and Heatley 1939 |
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Alexander Fleming |
-discovered Penicillin -observed penicillin activity on contaminated plate and did not think it could be developed further |
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Streptomycin |
-antibiotic active against tuberculosis -discovered by Selman Waksman 1944 (Awarded Nobel Prize in 1952) |
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Later discoveries by 1953 |
chloramphenicol, terramycin, neomycin, and tetracyline |
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selective toxicity |
ability of drug to kill or inhibit pathogen while damaging host as little as possible |
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therapeutic dose |
drug level required for clinical treatment |
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toxic dose |
drug level at which drug becomes too toxic for patient (ex. produces side effects) |
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therapeutic index |
ratio of toxic dose to therapeutic dose |
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broad-spectrum drugs |
attack many different pathogens |
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narrow-spectrum drugs |
attack only a few different pathogens |
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Minimal Inhibitory Concentration (MIC) |
lowest concentration of drug that inhibits growth of pathogen |
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Minimal Lethal Concentration (MLC) |
lowest concentration of a drug that kills pathogen |
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Dilution susceptibility tests |
-involves inoculating media containing different concentrations of drug |
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Disk Diffusion Tests |
-disks impregnated with specific drugs are placed on agar plates inoculated with test microbe -drug diffuses from disk into agar establishing concentration gradient -observe clear zones (no growth) around disks |
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Kirby-Bauer method |
-standardized method for disk diffusion test -sensitivity and resistance determine using tables that relate zone diameter to degree of microbial resistance -table values plotted and used to determine if concentration of drug reached in body will be effective |
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The E test |
-similar to disk diffusion except uses strip rather than disk -E-test strips contain a gradient of an antibiotic -intersection of elliptical zone of inhibition with strip indicated MIC |
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How to determine concentration of drug in blood |
microbiological, immunological, chemical, chromatographic, or enzymatic assays |
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Sulfonamides (sulfa drugs) |
-inhibit folic acid synthesis -broad spectrum |
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Factors influencing the effectiveness of antimicrobial drugs |
-ability of drug to reach site of infection -susceptibility of pathogen to drug -ability of drug to reach concentrations in body that exceed MIC of pathogen |
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Ability of drug to reach site of infection |
depends in part on mode of administration (oral, topical, parenteral routes) -drugs can be excluded by blood clots or necrotic tissue (dead tissue) |
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Penicillins |
most are 6-aminopenicillanic acid derivatives and differ in side chain attached to amino group -most crucial feature of molecules is the b-lactam ring |
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b-lactam ring of penicillins |
essential for bioactivity -many penicillin resistant organisms produce b-lactamas (penicllinase) which hydroxlyzes a bond in this ring |
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Penicillin mode of action |
block enzyme that catalyzes transpeptidation, prevents the synthesis of complete cell walls leading to lysis of cell -acts only on growing bacteria that are synthesizing new peptidoglycan |
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Cephalosporin |
-broad-spectrum antibiotics that can be used by most patients that are allergic to penicillin -structurally and functionally similar to penicilins |
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Vancomycin and Teicoplanin |
-glcopeptide antibiotics -inhibit cell wall synthiesis -vancomycin - important for treatment of antibiotic-resistant staphylococcal and ernterococcal infections |
