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Ch. 18 - Immune Disorders
Bauman - Microbiology with Diseases by Taxonomy 6th Edition
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302당신이 사용하는 게 아니라요?교과서 변경
18장, 문제 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

검증된 단계별 안내
1
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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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

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.
추천 영상:
06:59
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.
추천 영상:
02:57
Intro to Immune Response Damage

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.
추천 영상:
02:19
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