Ch. 14 Review
12. Which of the following is a nucleoside analog commonly used as a reverse transcriptase inhibitor in the treatment of HIV? A. acyclovir B. ribavirin C. adenine-arabinoside D. azidothymidine
D
16. Which of the following resistance mechanisms is the most nonspecific to a particular class of antimicrobials? A. drug modification B. target mimicry C. target modification D. efflux pump
D
20. The utility of an antibiogram is that it shows antimicrobial susceptibility trends A. over a large geographic area. B. for an individual patient. C. in research laboratory strains. D. in a localized population.
D
21. Which of the following has yielded compounds with the most antimicrobial activity? A. water B. air C. volcanoes D. soil
D
6. Which of the following terms refers to the ability of an antimicrobial drug to harm the target microbe without harming the host? A. mode of action B. therapeutic level C. spectrum of activity D. selective toxicity
D
39. How does the biology of HIV necessitate the need to treat HIV infections with multiple drugs?
Due to the fact that HIV remains dormant in cells even after HIV concentrations in the blood have disappeared, patients are forced to undergo drug therapy for life. Multiple drugs then need to be used in order to combat drug resistance.
True/False 22. Narrow-spectrum antimicrobials are commonly used for prophylaxis following surgery.
False
True/False 23. β-lactamases can degrade vancomycin.
False
True/False 25. If drug A produces a larger zone of inhibition than drug B on the Kirby-Bauer disk diffusion test, drug A should always be prescribed.
False
44. What is the difference between MIC and MBC?
MIC = amount required to inhibit growth MBC = amount required to kill 99.9% of bacteria (does not apply to bacteriostatic drugs)
33. Where do antimicrobials come from naturally? Why?
Many soil bacteria and archaea naturally produce many commonly employed antibiotics. Their ability to produce antibiotics gives them an advantage because it kills of their competition when competing for limited resources in their environment
True/False 24. Echinocandins, known as "penicillin for fungi," target β(1→3) glucan in fungal cell walls.
True
True/False 26. The rate of discovery of antimicrobial drugs has decreased significantly in recent decades.
True
38. What bacterial structural target would make an antibacterial drug selective for gram-negative bacteria? Provide one example of an antimicrobial compound that targets this structure.
You can use polymyxins (a natural peptide antibiotic) to target the cell wall. They are lipophilic with detergent-like properties and interact with the lipopolysaccharide component of the outer membrane of gram-negative bacteria.
29. Selective toxicity antimicrobials are easier to develop against bacteria because they are ________ cells, whereas human cells are eukaryotic.
prokaryotic
13. Which of the following is an antimalarial drug that is thought to increase ROS levels in target cells? A. artemisinin B. amphotericin b C. praziquantel D. pleconaril
A
15. Which of the following resistance mechanisms is commonly effective against a wide range of antimicrobials in multiple classes? A. efflux pump B. target mimicry C. target modification D. target overproduction
A
17. Which of the following types of drug-resistant bacteria do not typically persist in individuals as a member of their intestinal microbiota? A. MRSA B. VRE C. CRE D. ESBL-producing bacteria
A
18. In the Kirby-Bauer disk diffusion test, the _______ of the zone of inhibition is measured and used for interpretation. A. diameter B. microbial population C. circumference D. depth
A
2. Which of the following antimicrobial drugs is synthetic? A. sulfanilamide B. penicillin C. actinomycin D. neomycin
A
4. Which of the following routes of administration would be appropriate and convenient for home administration of an antimicrobial to treat a systemic infection? A. oral B. intravenous C. topical D. parenteral
A
8. Which of the following does not bind to the 50S ribosomal subunit? A. tetracyclines B. lincosamides C. macrolides D. chloramphenicol
A
47. Too often patients will stop taking antimicrobial drugs before the prescription is finished. What are factors that cause a patient to stop too soon, and what negative impacts could this have?
After the first couple of days or weeks of taking the drugs, the patient will begin to feel much better. This will cause the patient to stop taking these drugs because they feel better. However, not all of the bacteria causing the infection/illness may have been killed. These remaining bacteria can then lead to increased resistance of the drug, and a relapse of the infection/illness.
1. A scientist discovers that a soil bacterium he has been studying produces an antimicrobial that kills gram-negative bacteria. She isolates and purifies the antimicrobial compound, then chemically converts a chemical side chain to a hydroxyl group. When she tests the antimicrobial properties of this new version, she finds that this antimicrobial drug can now also kill gram-positive bacteria. The new antimicrobial drug with broad-spectrum activity is considered to be which of the following? A. resistant B. semisynthetic C. synthetic D. natural
B
11. Which of the following drug classes specifically inhibits neuronal transmission in helminths? A. quinolines B. avermectins C. amantadines D. imidazoles
B
3. Which of the following combinations would most likely contribute to the development of a superinfection? A. long-term use of narrow-spectrum antimicrobials B. long-term use of broad-spectrum antimicrobials C. short-term use of narrow-spectrum antimicrobials D. short-term use of broad-spectrum antimicrobials
B
7. Which of the following is not a type of β-lactam antimicrobial? A. penicillins B. glycopeptides C. cephalosporins D. monobactams
B
36. When is using a broad-spectrum antimicrobial drug warranted?
Broad-spectrum antimicrobial drugs can be warranted for serious systemic infections when there is no time to determine the causative agent. These drugs are used to treat the patient with this infection when awaiting lab results to determine the infectious pathogen. Narrow-spectrum drugs are used when a specific pathogen has been identified. Using this narrow spectrum drug will only target this one pathogen, and will not harm other microbials.
10. Which of the following is not an appropriate target for antifungal drugs? A. ergosterol B. chitin C. cholesterol D. β(1→3) glucan
C
14. Which of the following resistance mechanisms describes the function of β-lactamase? A. efflux pump B. target mimicry C. drug inactivation D. target overproduction
C
19. Which of the following techniques cannot be used to determine the minimum inhibitory concentration of an antimicrobial drug against a particular microbe? A. Etest B. microbroth dilution test C. Kirby-Bauer disk diffusion test D. macrobroth dilution test
C
5. Which clinical situation would be appropriate for treatment with a narrow-spectrum antimicrobial drug? A. treatment of a polymicrobic mixed infection in the intestine B. prophylaxis against infection after a surgical procedure C. treatment of strep throat caused by culture identified Streptococcus pyogenes D. empiric therapy of pneumonia while waiting for culture results
C
9. Which of the following antimicrobials inhibits the activity of DNA gyrase? A. polymyxin B B. clindamycin C. nalidixic acid D. rifampin
C
28. The bacterium known for causing pseudomembranous colitis, a potentially deadly superinfection, is ________.
Clostridium difficile
50. Why can't drugs used to treat influenza, like amantadines and neuraminidase inhibitors, be used to treat a wider variety of viral infections?
Each virus has different targets. If the same drugs to attack different viruses, this would create unintended resistance
32. The method that can determine the MICs of multiple antimicrobial drugs against a microbial strain using a single agar plate is called the ________.
Etest
51. Can an Etest be used to find the MBC of a drug? Explain.
Etest: used to determine MIC because it is a combination of Kirby-Bauer disk diffusion and dilution method test However the MBC cannot be determined by the Etest unlike macrobroth and microbrorh dilutions
52. Who should be responsible for discovering and developing new antibiotics? Support your answer with reasoning.
I believe that pharmaceutical companies should be responsible for discovering new antibiotics because that is their field. They should have the funds to research new drugs
45. In nature, why do antimicrobial-producing microbes commonly also have antimicrobial resistance genes?
In nature, antimicrobial-producing microbes also have antimicrobial resistance genes in order to protect themselves from antimicrobial compounds produced by other microbes. It is used as a defense mechanism against other organisms to protect itself.
34. Why was Salvarsan considered to be a "magic bullet" for the treatment of syphilis?
It was 606th compound tested for the treatment of syphilis, and this method of screening a variety of compounds is now a common strategy
46. Why are yeast infections a common type of superinfection that results from long-term use of broad-spectrum antimicrobials?
Long term use of broad-spectrum antimicrobials can result in a broad range of microbes that are killed. Often, many of these microbes that are killed are good, protective bacteria. The death of these cells can lead to superinfection, which is a secondary infection in a patient having a pre-existing condition. An example of a superinfection is yeast infections.
42. What is the difference between multidrug resistance and cross-resistance?
Multi-drug: carry one or more resistance mechanisms, making them resistant to multiple antimicrobials Cross-resistance: a single resistance mechanism confers resistance to multiple antimicrobial drugs
40. Niclosamide is insoluble and thus is not readily absorbed from the stomach into the bloodstream. How does the insolubility of niclosamide aid its effectiveness as a treatment for tapeworm infection?
Niclosamide inhibits ATP formation under anaerobic conditions and inhibit oxidative phosphorylation in the mitochondriaIt has high localized intestianl concentrations
37. If human cells and bacterial cells perform transcription, how are the rifamycins specific for bacterial infections?
Rifamycins are specific for bacterial infections because these drugs block transcription by binding to bacterial RNA polymerase, not eukaryotic RNA polymerase. Drugs can also target and disrupt the peptidoglycan membranes of bacterial cells, which human cells lack
41. Why does the length of time of antimicrobial treatment for tuberculosis contribute to the rise of resistant strains?
Since the antibiotics are administered for such a long period of time, this results in patient non-adherence. The patient does not take the prescription how they should be and any TB strains that survived the initial medications may develop resistance.
35. When prescribing antibiotics, what aspects of the patient's health history should the clinician ask about and why?
The clinician should know if the patient suffers from certain diseases. If the patient has taken other drugs in the past or is currently taking them, it is important to know what they are to examine any possible interactions that may occur. Also, the clinician should know if the patient suffers from liver or kidney dysfunctions. If the clinician doesn't know this, then they may prescribe a drug that the patient's body may not be able to fully metabolize, resulting in higher levels of toxicity and therefore more side effects.
48. In considering the cell structure of prokaryotes compared with that of eukaryotes, propose one possible reason for side effects in humans due to treatment of bacterial infections with protein synthesis inhibitors.
The ribosomes in prokaryotes differ from eukaryotes. Side effects can be phototoxicity and liver toxicity. This could be because certain proteins are blocked from being made or they altered and unable to do their normal job.
43. How is the information from a Kirby-Bauer disk diffusion test used for the recommendation of the clinical use of an antimicrobial drug?
The test doesn't necessarily show efficacy, but it shows which antibacterials a bacterial pathogen is susceptible to or resistant to
27. The group of soil bacteria known for their ability to produce a wide variety of antimicrobials is called the ________.
actinomycetes
31. Staphylococcus aureus, including MRSA strains, may commonly be carried as a normal member of the ________ microbiota in some people.
nasal
30. Antiviral drugs, like Tamiflu and Relenza, that are effective against the influenza virus by preventing viral escape from host cells are called ________.
neuraminidase inhibitors