15.E: Antimicrobial Drugs (Exercises)
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- Ying Liu
- City College of San Francisco
14.1: Discovering Antimicrobial Drugs
Antimicrobial drugs produced by purposeful fermentation and/or contained in plants have been used as traditional medicines in many cultures for millennia. The purposeful and systematic search for a chemical “magic bullet” that specifically target infectious microbes was initiated by Paul Ehrlich in the early 20th century. The discovery of the natural antibiotic, penicillin, by Alexander Fleming in 1928 started the modern age of antimicrobial discovery and research.
Multiple Choice
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?
- resistant
- semisynthetic
- synthetic
- natural
- Answer
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B
Which of the following antimicrobial drugs is synthetic?
- sulfanilamide
- penicillin
- actinomycin
- neomycin
- Answer
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A
Fill in the Blank
The group of soil bacteria known for their ability to produce a wide variety of antimicrobials is called the ________.
- Answer
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actinomycetes
Short Answer
Where do antimicrobials come from naturally? Why?
Why was Salvarsan considered to be a “magic bullet” for the treatment of syphilis?
Critical Thinking
In nature, why do antimicrobial-producing microbes commonly also have antimicrobial resistance genes?
14.2: Antibacterial Drugs
Antimicrobial drugs can be bacteriostatic or bactericidal, and these characteristics are important considerations when selecting the most appropriate drug. The use of narrow-spectrum antimicrobial drugs is preferred in many cases to avoid superinfection and the development of antimicrobial resistance. Broad-spectrum antimicrobial use is warranted for serious systemic infections when there is no time to determine the causative agent or when narrow-spectrum antimicrobials fail.
Multiple Choice
Which of the following combinations would most likely contribute to the development of a superinfection?
- long-term use of narrow-spectrum antimicrobials
- long-term use of broad-spectrum antimicrobials
- short-term use of narrow-spectrum antimicrobials
- short-term use of broad-spectrum antimicrobials
- Answer
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B
Which of the following routes of administration would be appropriate and convenient for home administration of an antimicrobial to treat a systemic infection?
- oral
- intravenous
- topical
- parenteral
- Answer
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A
Which clinical situation would be appropriate for treatment with a narrow-spectrum antimicrobial drug?
- treatment of a polymicrobic mixed infection in the intestine
- prophylaxis against infection after a surgical procedure
- treatment of strep throat caused by culture identified Streptococcus pyogenes
- empiric therapy of pneumonia while waiting for culture results
- Answer
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C
Fill in the Blank
The bacterium known for causing pseudomembranous colitis, a potentially deadly superinfection, is ________.
- Answer
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Clostridium difficile
True/False
Narrow-spectrum antimicrobials are commonly used for prophylaxis following surgery.
- Answer
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False
Short Answer
When prescribing antibiotics, what aspects of the patient’s health history should the clinician ask about and why?
When is using a broad-spectrum antimicrobial drug warranted?
Critical Thinking
Why are yeast infections a common type of superinfection that results from long-term use of broad-spectrum antimicrobials?
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?