When collecting sputum samples for Directly Observed Treatment, Short-course (DOTS), how many samples are typically required for testing?

Appeared in: NORCET 7 Prelims -2024

Explanation

Current national guidelines (NTEP, formerly RNTCP) in India recommend collecting two sputum samples for diagnosing pulmonary TB.
The standard protocol involves one 'spot' sample collected at the health facility and one 'early morning' sample collected by the patient at home the next day.
This updated two-sample strategy replaced the older three-sample method to improve patient adherence, reduce costs, and increase program efficiency.
The chance of detecting tubercle bacilli is significantly higher with two samples compared to just one.

Option A: A single sample is generally considered insufficient for a reliable diagnosis as it has lower sensitivity, increasing the risk of a false-negative result and potentially missing a case of active TB.
Option C: Collecting three sputum samples (Spot-Morning-Spot) was the standard under the older DOTS guidelines. This protocol is now outdated in India and many other countries.
Option D: Four samples are excessive and not recommended by any standard diagnostic protocol for tuberculosis. It would increase costs and patient burden without providing additional diagnostic benefit.

Clinical Relevance

Nursing practice connection: Knowing Sputum sample collection for Tuberculosis (TB) diagnosis under the National Tuberculosis Elimination Program (NTEP) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
A nurse's primary role is to provide clear instructions to the patient on how to produce a good quality deep-cough sputum sample, not just saliva, to ensure diagnostic accuracy.
Understanding the two-sample strategy is vital for public health nurses, as it helps reduce the patient dropout rate during diagnosis, which is a major challenge in TB control.
What if? If a patient lives in a remote area and cannot return the next day with a morning sample, the guidelines allow for a second spot sample to be collected at least one hour after the first one to complete the diagnostic requirement in a single visit.

How to Approach the Question

First, identify the core of the question, which is asking for the specific number of sputum samples required for TB diagnosis under the DOTS strategy.
This is a factual recall question based on current national health program guidelines (NTEP/RNTCP).
Recall or look for the most up-to-date protocol. Health guidelines are often revised.
Differentiate between the current protocol (two samples) and the historical one (three samples). Exam questions often test this change.
Eliminate the other options based on diagnostic principles: one sample is generally insufficient, and four is excessive and not standard practice.
Select the option that aligns with the current, evidence-based guidelines for efficiency and patient compliance.

Concept Tested & Keywords

Concept Tested: Sputum sample collection for Tuberculosis (TB) diagnosis under the National Tuberculosis Elimination Program (NTEP).
Stem keywords: sputum samples, Directly Observed Treatment, Short-course (DOTS), testing
Lead-in keywords: how many
Negative lead-in flag: false

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart B (pp 202-403 of 604) p. 23-25

E6 Microbiology Essentials Sastry 4e Part 2 p. 157-159

Practise the full NORCET 7 Prelims -2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.