Textbook Question
Given that both human cells and pathogens synthesize proteins at ribosomal sites, how can antimicrobial agents that target this process be safe to use in humans?
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Ch. 10 - Controlling Microbial Growth in the Body: Antimicrobial Drugs
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302
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Table of contents
- Ch. 1 - A Brief History of Microbiology31
- Ch. 2 - The Chemistry of Microbiology28
- Ch. 3 - Cell Structure and Function39
- Ch. 4 - Microscopy, Staining, and Classification25
- Ch. 5 - Microbial Metabolism51
- Ch. 6 - Microbial Nutrition and Growth37
- Ch. 7 - Microbial Genetics51
- Ch. 8 - Recombinant DNA Technology21
- Ch. 9 - Controlling Microbial Growth in the Environment36
- Ch. 10 - Controlling Microbial Growth in the Body: Antimicrobial Drugs21
- Ch. 11 - Characterizing and Classifying Prokaryotes29
- Ch. 12 - Characterizing and Classifying Eukaryotes34
- Ch. 13 - Characterizing and Classifying Viruses, Viroids, and Prions23
- Ch. 14 - Infection, Infectious Diseases, and Epidemiology35
- Ch. 15 - Innate Immunity34
- Ch. 16 - Adaptive Immunity21
- Ch. 17 - Immunization and Immune Testing29
- Ch. 18 - Immune Disorders22
- Ch. 19 - Pathogenic Gram-Positive Bacteria25
- Ch. 20 - Pathogenic Gram-Negative Cocci and Bacilli28
- Ch. 21 - Rickettsias, Chlamydias, Spirochetes, and Vibrios25
- Ch. 22 - Pathogenic Fungi47
- Ch. 23 - Parasitic Protozoa, Helminths, and Arthropod Vectors44
- Ch. 24 - Pathogenic DNA Viruses23
- Ch. 25 - Pathogenic RNA Viruses30
- Ch. 26 - Applied and Industrial Microbiology29
- Ch. 27 - Microbial Ecology and Microbiomes22
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302Not the one you use?Change textbook
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Bauman 6th EditionCh. 10 - Controlling Microbial Growth in the Body: Antimicrobial DrugsProblem 4
Bauman 6th EditionCh. 10 - Controlling Microbial Growth in the Body: Antimicrobial DrugsProblem 4Chapter 10, Problem 4
Which of the following statements is relevant in explaining why sulfonamides are effective?
a. Sulfonamides attach to sterol lipids in the pathogen, disrupt the membranes, and lyse the cells.
b. Sulfonamides prevent the incorporation of amino acids into polypeptide chains.
c. Humans and microbes use PABA differently in their metabolism.
d. Sulfonamides inhibit DNA replication in both pathogens and human cells.
Verified step by step guidance1
Understand the mechanism of action of sulfonamides: Sulfonamides are antimicrobial agents that interfere with the synthesis of folic acid in bacteria.
Recall that folic acid is essential for the synthesis of nucleotides, which are the building blocks of DNA and RNA, and that bacteria synthesize folic acid from para-aminobenzoic acid (PABA).
Recognize that sulfonamides are structural analogs of PABA and competitively inhibit the enzyme dihydropteroate synthase, which incorporates PABA into folic acid synthesis in bacteria.
Note that humans do not synthesize folic acid and instead obtain it from their diet, so the metabolic pathway involving PABA is different in humans compared to bacteria.
Conclude that the relevant explanation for sulfonamide effectiveness is that humans and microbes use PABA differently in their metabolism, making option (c) the correct choice.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Mechanism of Action of Sulfonamides
Sulfonamides are antimicrobial agents that inhibit the synthesis of folic acid in bacteria by acting as competitive inhibitors of para-aminobenzoic acid (PABA). This disruption prevents the production of nucleotides necessary for DNA and RNA synthesis, leading to bacterial growth inhibition.
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Introduction to Avoiding Host Defense Mechanisms
Role of PABA in Microbial Metabolism
PABA is a precursor molecule used by bacteria to synthesize folic acid, an essential vitamin for nucleic acid production. Humans do not synthesize folic acid and instead obtain it from their diet, making PABA metabolism a selective target for antibiotics like sulfonamides.
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Selective Toxicity in Antimicrobial Therapy
Selective toxicity refers to the ability of a drug to target microbial cells without harming human cells. Sulfonamides exploit differences in folic acid metabolism between microbes and humans, allowing them to inhibit bacterial growth while minimizing effects on human cells.
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Related Practice
Textbook Question
Multiple-drug-resistant microbes _____________________ .
a. Are resistant to all antimicrobial agents
b. Respond to new antimicrobials by developing resistance
c. Frequently develop in hospitals
d. All of the above
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Textbook Question
Support or refute the following statement: Antimicrobial agents make cells become resistant.
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Textbook Question
Why is the fact that drug Z destroys the NAM portions of a cell’s wall structure an important factor in considering the drug for chemotherapy?
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Textbook Question
Cross resistance is __________ .
a. The deactivation of an antimicrobial agent by a bacterial enzyme
b. Alteration of the resistant cells so that an antimicrobial agent cannot attach
c. The mutation of genes that affect the cytoplasmic membrane channels so that antimicrobial agents cannot cross into the cell’s interior
d. Resistance to one antimicrobial agent because of its similarity to another antimicrobial agent
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Textbook Question
The key to successful chemotherapy is __________ .
a. Selective toxicity
b. A diffusion test
c. The minimum inhibitory concentration test
d. The spectrum of action
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