Immune status in diphtheria can be tested by?

AIIMS Bhuvneshwar NO- 2018

Microbiology

Easy

Appeared in: AIIMS Bhuvneshwar NO- 2018

Explanation

The Schick test is specifically designed to determine a person's immune status against diphtheria.
It works by injecting a small amount of diphtheria toxin under the skin.
If a person is immune, their antibodies neutralize the toxin, and no reaction occurs (a negative result).
If a person is not immune (susceptible), the toxin causes a local inflammatory reaction of redness and swelling (a positive result).

Option A: The Frei test (commonly misspelled as Fren's test) is associated with Lymphogranuloma Venereum (LGV), a sexually transmitted infection caused by Chlamydia trachomatis, not diphtheria.
Option C: The Lepromin test is used in the management of leprosy (Hansen's disease). It helps classify the type of leprosy a person has (tuberculoid vs. lepromatous) by assessing their cell-mediated immunity to Mycobacterium leprae.
Option D: The Dick test is used to determine susceptibility to scarlet fever, which is caused by the erythrogenic toxin from Streptococcus pyogenes bacteria.

Visual 1: Diagram - A comparative chart showing the four skin tests (Schick, Dick, Lepromin, Frei), the associated disease, the substance injected, and the interpretation of a positive result.
Visual 2: Illustration - An image depicting the forearm with a positive Schick test reaction (redness and induration) versus a negative reaction (no change in the skin).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Immunological skin tests for infectious diseases as background academic context rather than a clinical decision trigger.
A key nursing responsibility is to check the immunization status of patients, especially for vaccine-preventable diseases like diphtheria. A positive Schick test (or low serology titers) indicates the need for a booster dose of the Tdap vaccine.
Nurses must be able to differentiate between these similarly named tests to understand diagnostic procedures and patient results correctly.
If a patient presents with symptoms of diphtheria (e.g., sore throat, low-grade fever, adherent gray membrane on tonsils), the nurse's priority is to implement droplet precautions immediately to prevent transmission, even before the diagnosis is confirmed.

How to Approach the Question

First, identify the key disease in the question stem, which is 'diphtheria'.
This is a factual recall question. Your goal is to match the disease with its specific diagnostic or susceptibility test.
Systematically review the options. Recall or deduce the purpose of each test.
Eliminate the options associated with other diseases: Lepromin test for leprosy, Dick test for scarlet fever, and Frei test for LGV.
This process of elimination leaves the Schick test as the only one related to diphtheria.
To prepare for such questions, create a study table comparing different eponymously named tests, their associated diseases, and their principles. This helps in quick recall and avoids confusion.

Concept Tested & Keywords

Qxa3focByNUAur-9lvzdaZ