Which of the following tests is used to detect Typhoid?

RRB Staff Nurse Kolkata-2015

Microbiology

Easy

Appeared in: RRB Staff Nurse Kolkata-2015

Explanation

The Widal test is a classic serological agglutination test used to help diagnose typhoid (enteric) fever.
It functions by detecting the presence of specific antibodies (agglutinins) in the patient's serum that have formed in response to the antigens of the Salmonella bacteria.
The test specifically looks for antibodies against the somatic (O) and flagellar (H) antigens of Salmonella enterica serotype Typhi.
A diagnosis is often supported by a single high titer or, more reliably, a fourfold or greater increase in the antibody titer in paired serum samples collected 7-10 days apart.

Option A: VDRL (Venereal Disease Research Laboratory) is a non-treponemal test used for screening for syphilis, which is caused by the bacterium Treponema pallidum. It is not used for diagnosing typhoid fever.
Option C: BCG (Bacillus Calmette-Guérin) is not a diagnostic test; it is a vaccine used for the prevention of tuberculosis (TB).
Option D: UDRL is not a standard or recognized acronym for a medical test. It is most likely a typographical error for VDRL.

Visual 1: Diagram - Illustrating the principle of the Widal test. This would show Salmonella antigens being mixed with patient serum. A positive result would depict agglutination (clumping) of the antigens by the antibodies, while a negative result would show no clumping.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Diagnostic test for Typhoid fever as background academic context rather than a clinical decision trigger.
Nurses must understand the correct timing for typhoid diagnostics. Blood culture is the investigation of choice in the first week of fever, whereas the Widal test is more reliable from the second week onwards.
Patient education is a key nursing role. It's important to explain that a single Widal test result can be misleading, especially in endemic areas, and that follow-up testing or other tests might be necessary for a definitive diagnosis.
What if? If a patient in an endemic area has a single low-positive Widal titer (e.g., 1:80) but a persistent high fever, the nurse should anticipate the physician ordering a blood culture to confirm or rule out typhoid, as the Widal result is inconclusive.

How to Approach the Question

First, identify the key concept in the question stem, which is the specific diagnostic test for 'Typhoid'.
Next, evaluate each option based on your medical knowledge.
Recall that VDRL is for syphilis. Eliminate this option.
Recall that BCG is a vaccine for tuberculosis, not a diagnostic test. Eliminate this option.
Recognize that 'UDRL' is not a standard medical acronym, making it an incorrect choice.
By elimination, WIDAL is the only remaining and correct option, which is a well-known serological test for typhoid fever.

Concept Tested & Keywords

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