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53 Cards in this Set
- Front
- Back
Define selective toxicity.
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Kills the invading organism and spares the host
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What is a bactericidal?
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the organisms are killed
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What is a bacteriostatic?
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the organisms are prevented from growing
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Why can some agents be bacteriostatic and bactericidal?
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depends on the concentration of drug achieved at the site of infection and the target bacteria
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What type of agents must be used i immunocompetent patients without complement or proper immunity/antibody function?
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bactericidal (kills organisms directly)
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What is the post antibiotic effect (PAE)?
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persistent suppression of organism growth after concentrations fall beneath the MIC
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What is MIC (Minimum Inhibitory Concentration)?
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lowest concentration of an antimicrobial agent that prevents visible growth after an 18-24 hour incubation period
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What is MBC (Minimum Bactericidal Concentration)?
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minimal concentration that kills 99.9% of bacterial cells
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What conditions require that you know the MBC?
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endocarditis, osteomyelitis, and meningitis
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What factors can be used to confirm the presence of an infection?
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fever, leukocytosis, tachycardia, local signs, mental status changes like confusion and lethargy, chills/rigors
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What is the fastest, simplest, and most inexpensive method used to identify types of organisms?
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gram stain
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This identification method provides conclusion identification and precise targeting of therapy, but it takes more time to get than a Gram stain.
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Culture and Sensitivity
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How do you empirically select an antimicrobial agent?
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based on the most likely factor, host factors, and drug factors
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What are the methods for monitoring therapeutic response?
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improvement in symptoms (local and systemic), lab tests (WBC, culture negative),
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What is considered therapeutic failure?
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no improvement or worsening of symptoms
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3 considerations in antibiotic use
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host, drug, and bug
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How long might it take to determine susceptibility of a bug to antibiotics?
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18 to 48 hours
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What is the Disk Diffusion method?
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most common means to determine antibiotic susceptibility
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Length of time it takes to get result with Disk Diffusion Method
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18-24 hours
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Which test is a quantitative test that determines the MBC and MIC?
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Dilution Test
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What is important to differentiate when someone has a allergy history to a antimicrobial agent?
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anaphylaxis versus rash
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What two classes of antibiotics are best known for allergic reactions?
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penicillins and cephalosporins
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What side effect do Tetracyclines have in kids?
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yellow teeth
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What side effect do FQ have in kid?
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joint and cartilage infections
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What population is it important to assess renal function in when using antimicrobial?
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elderly because they have fewer functioning nephrons
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In diabetic foot infections, what is the concern when selecting antibiotics?
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antibiotics will be appropriate for bacteria present, however the drug cannot reach the site due to poor perfusion secondary to swelling and co morbid disease state
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This method id antimicrobial administration is the most reliable but the least convenient
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IV route
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Why does inflammation facilitate antibiotic distribution?
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it increases blood flow to the area
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What is the most pertinent distribution issue in antibiotic use ?
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adequate antibiotics must reach the infection site
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What drugs in particular must you monitor CNS toxicity with?
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penicillins, cephalosporins, quinolones, and imipenem
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What drug is known for causing neutropenia?
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nafcillin
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What drug is known for causing platelet dysfunction?
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piperacillin
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What drug is known for causing hypoprothombinemia?
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cefotetan
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What drug is known for causing bone marrow suppression?
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chloramphenicol
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What drug is known for causing megaloblastic anemia?
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Trimethoprim (Bactrin)
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What drugs are known for nephrotoxicity?
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aminoglycosides and vancomycin (reversible upon discontinuation)
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What drugs are known for causing photosensitivity?
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quinolones, tetracylcines, sulfonamides
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What drugs are known for causing diarrhea/colitis?
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clindamycin because it wipes out normal flora of GI tract
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These drugs are effective against a single or limited group of microorganisms
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narrow spectrum
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These drugs are effective against a large number of gram positive and some gram negative bacteria
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extended spectrum
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These drugs are effective against a wide variety of microbial species (gram positive, gram negative, and anaerobic bacteria)
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broad spectrum
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Example of broad spectrum antibiotic
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Fluoroquinolones (Moxifloxacin)
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Why should you use single agents to treat infections whenever possible?
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reduces likelihood of resistance; also using multiple agents can disrupt the action of a single agent and increase toxicity risk
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What situations require combinations of drugs?
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life threatening infections in immunocompromised/chronically ill, empirically when no one agent is known to be effective, to decrease emergence of resistant strains, to decrease toxicity by lower dose, and when synergism is needed
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What is synergism?
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inhibitory or killing ability of 2 antimicrobials is greater than the expected ability based on their individual effects
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How often do you reevaluate response to antibiotics?
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every 2-3 days
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Failures caused by the drug itself can be due to what?
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inappropriate drug selection, inappropriate dosage, inappropriate route of administration (poor penetration to site of infection)
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Failures due to bug factors can be due to what?
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bacterial resistance, infections that are non bacterial in origin, or undetected microorganism in polymicrobial infection’
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What is bacterial resistance?
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growth is not halted by maximal level of antibiotic tolerated by the host
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What is innate resistance?
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resistance as a result of the natural design of bacteria and the design of the drug's MOA
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What is acquired resistance?
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resistance adapted through spontaneous mutation or DNA transfer of drug resistance
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When should antimicrobial prophylaxis be used?
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when efficacy has been proven and the benefits of prophylactic treatment outweigh the risk of resistance
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Two types of antibiotic prophylaxis
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surgical (upper GI, colon, prosthetics, C section, and dirty surgery) and non surgical (prevent UTIs, bacterial endocarditis)
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