19933890
Description
Flashcards by Katherine Havighorst, updated more than 1 year ago
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Created by Katherine Havighorst
about 5 years ago
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| Question | Answer |
| What are the four quadrants of spectrum? | Gram + Aerobic Gram - Aerobic Gram + Anaerobic Gram - Anaerobic |
| What is the mechanism of action of bacteriostatic drugs? | -inhibit protein synthesis or metabolism -prevents further cell division without killing the bacteria -normal host defense mechanism must participate |
| How do bacteriostatic drugs react with other drugs? | -can antagonize select bactericidal drugs -can become bactericidal if given in high doses or combined with select agents |
| What is the mechanism of action of bactericidal drugs? | kill the bacteria -cell wall synthesis inhibitors, DNA gyrase inhibition, DNA degradation during replication, membrane disruption |
| Why can bactericidals cause superinfections? | they are more likely to kill off normal flora than bacteristatics |
| What is the process of a Kirby Bauer test? | -add antibiotic impregnated discs to the surface of a bacterial agar plate -the drug diffuses on contact with agar -size of the zone of inhibition of growth predicts sensitivity -BUT. difficult to quality control |
| Why might a 96-well Format Microtiter Plate be a better test than Kirby Bauer when determining sensitivity? | -broth concentrations parallel serum concentrations, making it a better model than KB -uses dehydrated antimicrobials, which increases shelf-life -able to test a far greater number of drugs/drug concentrations -Quality control relatively easy, results are reliable |
| Explain the use and process of an E-test | -Enables testing of a single preferred drug for multiple organisms at a lower cost -Measure where the zone intersects the strip -Useful for fastidious organisms that grow poorly in broth |
| What data is needed to establish a a breakpoint? | Epidemiological: fit within the limits of clusters of susceptible and resistant bacterial populations Pharmacological: upper limit for susceptibility must be lower than levels that may be achieved in sera or tissues Clinical: the susceptible population should respond clinically and reasonably correlated to in vivo results |
| What are reasons an organism may be intrinsically resistant to a drug? | -they lack the target -they have an altered target -the drug cannot enter the organism -an efflux mechanism pumps the drug back out -an alternate metabolic route is used by the organism |
| Why might an antimicrobial be placed into group D? | -contraindication -residues -drug of last resort for humans |
| List the 6 basics of antibiogram design | 1. Analyze and prepare an antibiogram AT LEAST anually 2. include only final verified results 3. include only species with data for 30+ isolates 4. Include only diagnostic isolates (not surveillance isolates) 5. Do not include duplicates from the same patient 6. Report the % S for agents that are routinely tested and reported |
| What is the value of MIC90 Tables? | -Make more informed empirical tx decisions -Earlier tx to reduce losses -Represent a continuum; not a cutoff -You know you can have 90% likelihood of success treating with this antibiotic |
| What 3 types of antimicrobial agents work by inhibiting cell wall synthesis? | Penicillins Carbapenems Monobactams |
| What are narrow spectrum penicillins? | Penicilin G Penicillin V |
| What are common aminopenicillins? | Ampicillin Amoxicillin |
| What are common penicillinase-resistant / antistaphylococcal penicillins? | Nafcillin Methicillin Oxacillin |
| What are common extended spectrum penicillins? | Piperacillin Ticarcillin |
| What are common B-lactamase inhibitors? | Clavulanic ACid Sulbactam Tazobactam |
| What is a common carbapenem? | Imipenem |
| What is a common monobactem? | Aztreonam |
| What is the MoA of penicillin? | -Bind to transpeptidases [penicillin binding proteins] and inhibit peptidoglycan synthesis -inhibiting transpeptidases destabilizes cell wall |
| Are B-lactams bacteriostatic or bactericidal? | Bactericidal |
| Why are B-lactamase inhibitors combined with penicillin? | B-lactamase inhibitors extend the spectrum of penicillin to include bacteria that express B-lactamases |
| What is the MoA of Carbapenems? | Same as penicillin-bind to transpeptidases and inhibit cell wall synthesis |
| When are monobactams used? | -Only active against aerobic GNR -given in place of aminoglycoside for very narrow coverage of aerobic GNR like E. Coli |
| Give common 1st and 3rd generation cephalosporins | First: cefazolin, cephalexin Third: ceftiofur, ceftazidime, cefovecin, ceftriaxone |
| How do cephalosdporins compare to penicillins? | Cephalosporins are -less sensitive to GI amidases -less sensitive to bacterial B-lactamases -less sensitive to alkalinity -resistant to acidity |
| What drugs are inhibitors of ribosomal 30s subunit? | Aminoglycosides Tetracycline |
| What drugs are inhibitors of ribosomal 50S subunit? | Macrolides Lincosamides Phenicols |
| What are common macrolides? | Group A: Tulathromycin, Tilmicosin Group B: Erythromycin Group C: Tylosin |
| Are macrolides bacteriostatic or bactericidal? | Bacteriostatic |
| What are common types of Lincosamides? | Lincomycin Clindamycin Pirlimycin |
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