Textbook Question
Indicate whether each statement is true or false. If the statement is false, change the underlined word or phrase to make the statement true.
______Graft-versus-host disease can follow a bone marrow isograft.
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Ch. 18 - Immune Disorders
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
Chapter 18, Problem 5
A positive tuberculin skin test indicates that a patient not immunized against tuberculosis:
a. Is free of tuberculosis
b. Is shedding Mycobacterium
c. Has been exposed to tuberculosis antigens
d. Is susceptible to tuberculosis
e. Is resistant to tuberculosis
Verified step by step guidance1
Understand what a tuberculin skin test (TST) measures: it detects a delayed-type hypersensitivity reaction to purified protein derivative (PPD) from Mycobacterium tuberculosis, indicating immune system recognition of tuberculosis antigens.
Recognize that a positive TST means the immune system has been sensitized to tuberculosis antigens, which usually occurs after exposure to the bacteria or vaccination with BCG (though in this problem, the patient is not immunized).
Eliminate options that do not align with the meaning of a positive test: it does not mean the patient is free of tuberculosis (a), nor does it directly indicate active shedding of bacteria (b), susceptibility (d), or resistance (e).
Focus on the fact that a positive test reflects prior exposure to tuberculosis antigens, which triggers the immune response detected by the test.
Conclude that the correct interpretation is that the patient has been exposed to tuberculosis antigens, even if they do not currently have active disease.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Tuberculin Skin Test (TST)
The tuberculin skin test is a diagnostic tool used to detect immune sensitization to Mycobacterium tuberculosis antigens. A positive result indicates that the person's immune system has previously encountered TB antigens, causing a delayed hypersensitivity reaction at the injection site.
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The Ames Test
Immune Response to Tuberculosis
When exposed to Mycobacterium tuberculosis, the immune system mounts a cell-mediated response involving T cells. This response leads to the formation of a localized skin reaction in the TST, reflecting prior exposure or infection, but not necessarily active disease or contagiousness.
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Interpretation of a Positive TST
A positive tuberculin skin test means the individual has been exposed to TB antigens, either through infection or vaccination. It does not confirm active disease, contagiousness, or immunity, but indicates sensitization to the bacteria.
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02:19Positive Feedback
Related Practice
Textbook Question
Compare and contrast the functions of four classes of immunosuppressive drugs.
Textbook Question
When a surgeon conducts a cardiac bypass operation by transplanting a piece of vein from a patient’s leg to the same patient’s heart, this is a(n):
a. Rejected graft
b. Autograft
c. Allograft
d. Type IV hypersensitivity
e. Cardiograft
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Textbook Question
Farmer’s lung is a hypersensitivity pneumonitis resulting from:
a. A type I hypersensitivity reaction to grass pollen
b. A type II hypersensitivity to red cells in the lung
c. A type III hypersensitivity to mold spores
d. A type IV hypersensitivity to bacterial antigens
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Textbook Question
Indicate whether each statement is true or false. If the statement is false, change the underlined word or phrase to make the statement true.
______ The tuberculin reaction is a type I hypersensitivity.
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Textbook Question
Which of the following is an autoimmune disease?
a. A heart attack
b. Acute anaphylaxis
c. Farmer’s lung
d. Graft-versus-host disease
e. Systemic lupus erythematosus
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