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25 Cards in this Set
- Front
- Back
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what do bacteriostatic agents do
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inhibit growth and reproduction of bacteria without killing them
work with the immune system to remove microorganisms from the body |
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Concentration dependent killing
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Bacterial kill increases with increasing levels of drug
The drug concentrations is important, not the time above the MIC. More drug kills more bugs. May have a concentration-dependent postantibiotic effect (PAE) |
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Time dependent killing
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The period of time drug concentrations are maintained above the MIC is important
Time above MIC is variable & depends on pathogen, infection site and drug In general, drugs are maintained above the MIC at least 40-50% of the time between dosing intervals Higher concentrations of drug does not result in a greater killing of bacteria Tend to have minimal to no postantibiotic effect (PAE) |
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bacteriocidal agents are required for Tx of what?
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endocarditits and other endovascular infections
meningitis infections in neutropenic cancer px's |
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what is absolute vs relative selectivity?
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absolute - targets something that only bacteria have - cell wall
relative - target something bacteria have and we have some too - like particular ribosome - affects us but doesnt kill us |
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5 major mechanisms of action for ABX
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1. inhibit cell wall synth
2. disruption of cell membrane function 3. inhibition of protein synth 4. inhibition of nucleic acid synth 5. action as antimetabolites |
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Types of drugs that inhibit bacterial cell wall synth
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B-lactams
vancomycin bacitracin cephalosporins penecillins |
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common drugs that inhibit protein synth - via ribosomal block
reversible or irreversible - details |
reversible and generally bacteriostatic - chloramphenicol, tetracyclines, erythromycin, and clindamycin
irreversible - aminoglycosides - generally bacteriocidal |
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drugs that inhibit bacterial cell membrane activity
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polymyxins
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drugs that affect synthesis of metabolites
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sulfonamides, trimethoprim
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drugs that inhibit nucleic acid synth, types?
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RNA poly inhibitors
Bacterial DNA replication disruptors gyrase inhibitors fluoroqinolones, rifampin |
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intrinsic ABX resistance?
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bacteria resistant naturally, without prior exposure to antibiotic
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acquired drug resistance
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bacteria change or acquire new DNA that results in new antibiotic resistance
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reasons why bacteria may be resistant to a drug - 3
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Drug does not reach target - decrease influx or increase efflux
drug is not active - increase rate of inactivation OR limited formation of active form of drug Target is altered - target deleted, target modified, acquisition of resistant form of native, susceptible target |
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2 mechanisms of ACQUIRED resistance
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mutation selection - vertical pressure
gene transfer- horizontal - transduction, tranformation, conjugation |
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what is transduction in acquired resistance?
important in what organism? |
DNA of one bacteria is introduced into another via a PHAGE - same species
important in S. Aureus |
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what is Transformation in acquired resistance?
seen in what organism? |
DNA uptake from lysed bacteria
penecillin resistance in pneumococci and Neisseria |
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what is conjugation?
seen between what sorts of bacteria? how common is this? |
gene transfer through direct cell to cell contact.
can occur between same strain, different strains, different species can transfer multiple genes MAJOR MECHANISM OF RESISTANCE TRANSFER |
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what are transposons
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jumping genes - in conjugation
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types of antimicrobial therapy - explain - 3
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empirical - broad spectrum when organism not identified
definitive therapy - narrow specturm drug after known species and susceptibility prophylactic therapy - spectrum depends on situtation |
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when is empirical therapy highly justified? (4)
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neutropenic px's
febrile cancer px's In community acquired pneumonia Also endocarditis |
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appropriate times when prophylactic therapy should be used - 2
particular dzs |
protect after exposure
protect before procedure and keep on to prevent after procudre seen in: anthrax, malaria, cholera, rheum fever, plague, influenza |
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potential effects of antimicrobial combination therapy
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additive
synergistic antagonistic potentiation - a drug is added and does nothing but potentiate the effect of another drug |
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pneumonic for bacteriostatic agents
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ECSTaTiC
erythromycin clindamycin sulfamethoxazole Trimethoprim Tetrayclines Chloramphenicol |
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pneumonic for bacteriocidal agents
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Very Finely Proficient At Cell Murder
Vancomycin Fluoroquinolones Penecilin Aminoglyocisdes Cephalosporins Metronidazole |
