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Ch. 15 - Antimicrobial Drugs
Norman-McKay- Microbiology: Basic and Clinical Principles 2nd Edition
Norman-McKay2nd EditionMicrobiology: Basic and Clinical PrinciplesISBN: 9780137661619Not the one you use?Change textbook
All textbooksNorman-McKay 2nd EditionCh. 15 - Antimicrobial DrugsProblem 1
Chapter 15, Problem 1

A broad-spectrum drug is best described as
a. bactericidal against a wide range of species.
b. bacteriostatic against a wide range of species.
c. effective against a wide range of species.
d. empiric therapy.
e. selectively toxic.

Verified step by step guidance
1
Step 1: Understand the term 'broad-spectrum drug' in microbiology. It refers to an antimicrobial agent that is effective against a wide variety of microbial species, including both Gram-positive and Gram-negative bacteria, or sometimes even other types of microbes.
Step 2: Review the options given: (a) bactericidal against a wide range, (b) bacteriostatic against a wide range, (c) effective against a wide range, (d) empiric therapy, and (e) selectively toxic.
Step 3: Differentiate between bactericidal and bacteriostatic. Bactericidal drugs kill bacteria, while bacteriostatic drugs inhibit their growth. Both can be broad-spectrum or narrow-spectrum, so these terms alone do not define 'broad-spectrum'.
Step 4: Consider 'empiric therapy' which refers to treatment given before the exact cause is known, often using broad-spectrum drugs, but it is a treatment approach, not a drug description.
Step 5: Recognize that 'selectively toxic' means the drug targets microbes without harming the host, which is a desirable property but not synonymous with broad-spectrum activity. Therefore, the best description of a broad-spectrum drug is that it is effective against a wide range of species.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Broad-spectrum drug

A broad-spectrum drug is an antimicrobial agent effective against a wide variety of microbial species, including both Gram-positive and Gram-negative bacteria. It is used when the specific pathogen is unknown or when multiple types of bacteria are involved in an infection.
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Bactericidal vs. Bacteriostatic

Bactericidal drugs kill bacteria directly, while bacteriostatic drugs inhibit bacterial growth and reproduction, allowing the immune system to eliminate the infection. Both types can be broad-spectrum or narrow-spectrum depending on their range of activity.
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Empiric therapy

Empiric therapy refers to the use of antibiotics based on clinical judgment and experience before specific pathogen identification. It often involves broad-spectrum drugs to cover likely pathogens until lab results guide targeted treatment.
Related Practice
Textbook Question

A patient has an uncomplicated infection with a Gram-negative bacterium. He also has a history of penicillin allergy. Which drug is the best treatment option for this patient?

a. Ampicillin

b. A first-generation cephalosporin

c. A carbapenem

d. Isoniazid

e. Azithromycin

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Textbook Question

A patient who is not a healthcare worker is diagnosed with C. difficile pseudomembranous colitis. What most likely led to this infection?

a. The patient was recently treated with a bacteriostatic drug.

b. The patient was recently treated with a broad-spectrum drug.

c. The patient was treated with a bactericidal drug.

d. The patient recently became immune compromised and therefore had an increased risk for infection.

e. The patient was recently exposed to someone with an active C. difficile infection.

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Textbook Question

Match the antimicrobial drug class to its action. You may assign more than one drug class to a given action and some actions may not be applicable.

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