Wk 6. Antibiotics part 1 Flashcards Preview

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Flashcards in Wk 6. Antibiotics part 1 Deck (29)
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1. What is selective toxicity? Why is it important?

Injuring a target cell or organism without injuring other cells or organisms in intimate contact with the target. Makes antibiotics safer.


2. What is the difference between bactericidal and bacteriostatic?

Bactericidal – kills bacteria
Bacteriostatic – slows growth, phagocytes eliminate bacteria


3. What are ranges and chances of drug resistance with narrow-spectrum and broad-spectrum antibiotics?

Narrow: smaller range
less resistance
Broad: larger range
more resistance


4. What is acquired resistance? What are four ways bacteria become resistant to antibiotics? How do we lessen the chance for resistance?

Bacteria become less susceptible or lose sensitivity to drug.
1) Reduce drug concentration at sites, 2) Alter drug receptors, 3) Synthesize an antagonist, & 4) Produce drug-metabolizing enzymes.
Treat infection, not colonization, and use correct drug in correct concentration for entire course of therapy.


5. What is the difference between the MIC and MBC?

MIC – amount of drug required to halt growth
MBC – amount of drug required to kill 99.9%


6. Explain the importance of conjugation. What bacteria are most affected?

Conjugation allows the DNA code for drug resistance to be passed to other bacteria. Gram negative bacteria.


7. What are two examples of suprainfections?

Candidiasis (yeast infection), Clostridium difficile infection (CDI) – 3 or more unformed stools in 24 hours with C. difficile or toxin from C. difficile in stools.


8. What is the difference between an additive and potentiative effect?

Additive – sum of the effect
Potentiative – greater than the sum of the effects


9. How do penicillins kill bacteria?

Disrupts cell wall (inhibits cross-linkages between peptidoglycan strands and lyses cell wall bonds)


10. What is the major adverse effect of penicillins?

Allergic reactions


11. What are some common signs and symptoms of anaphylaxis and serum sickness to penicillins?

Laryngeal edema, bronchoconstriction, severe hypotension, nausea and vomiting, tachycardia
Rash, hives, pruritis, arthralgias, fever


12. Which three penicillins can be taken with food?

Penicillin V, Amoxicillin, Augmentin


13. Why is Penicillin G given IM?

Destroyed by gastric acid


14. What lab abnormality can occur with Penicillin G or V when administered with potassium supplements?



15. What types of enzymes can destroy the penicillin molecule?

General beta-lactamases and penicillinases. Cephalosporinases deactivate cephalosporins.


16. What is the advantage of Nafcillin over other penicillins?



17. Amoxicillin has what kind of bacterial spectrum?



18. How does clavulanic acid prevent amoxicillin from being deactivated?

Clavulanic acid inhibits beta-lactamase


19. What are other beta-lactam antibiotic groups other than the penicillins?

Cephalosporins, carbapenems


20. How do cephalosporins kill bacteria?

Inhibits cell wall synthesis


21. Each subsequent generation of cephalosporins show more activity against what type of bacteria? How does each subsequent generation penetrate into the cerebral spinal fluid?

Gram negative bacteria and anaerobes, more resistant to beta-lactamases.
Each subsequent generation is more likely to reach the cerebral spinal fluid.


22. What percentage of penicillin-allergic patients will have an allergic reaction to a cephalosporin?



23. What is the adverse effect seen with some cephalosporins and alcohol?

Antabuse-like effects: weakness, pulsating headache, chest pain, abdominal cramps


24. What is the drug interaction is seen between IV calcium and IV cephalosporins?

Lung and renal precipitates.


25. How does vancomycin kill bacteria? What bacteria does it kill?

Inhibits cell wall synthesis. Gram-positive bacteria.


26. For what types of infection is vancomycin reserved? How is it given for CDI?

Severe C. difficile infections (CDIs), MRSA, & Staph. Epidermidis. Must be given PO for CDI, because cannot cross between GI tract and bloodstream.


27. What are the signs and symptoms of Red Man Syndrome seen with the rapid infusion of vancomycin?

Red rash, hives, flushing, and pruritis on face & upper body. Hypotension, tachycardia. From histamine release, NOT an allergic reaction.


28. Creatinine (Cr) is monitored with vancomycin therapy to avoid what? What is an indication for stopping vancomycin?

Renal failure. Stop if Cr rises 50%.


29. Aztreonam is used to treat what type of infection? Why?

Gram-negative aerobic bacteria. Only attaches to PBPs on gram-negative aerobic bacteria.