Acid-fast bacilli are found positive in which of the following conditions?

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

Acid-fast bacilli (AFB) are bacteria that resist decolorization by acids during staining procedures due to the high mycolic acid content in their cell walls.
The genus Mycobacterium contains the most clinically significant acid-fast organisms.
Tuberculosis is caused by Mycobacterium tuberculosis, a well-known acid-fast bacillus.
Leprosy is caused by Mycobacterium leprae, which is also an acid-fast bacillus.
Therefore, laboratory tests for acid-fast bacilli will be positive in both Tuberculosis and Leprosy.

Option B: SARS (Severe Acute Respiratory Syndrome) is caused by a coronavirus, not a bacterium, so acid-fast staining is not applicable. Diphtheria is caused by Corynebacterium diphtheriae, which is a non-acid-fast, Gram-positive bacterium.
Option C: While it is true that acid-fast bacilli are found in Tuberculosis, this answer is incomplete. Leprosy is also caused by an acid-fast bacillus, making the option that includes both diseases the best and most comprehensive choice.
Option D: Diphtheria is caused by Corynebacterium diphtheriae. This bacterium is Gram-positive but is not acid-fast; its cell wall lacks the high concentration of mycolic acid found in mycobacteria.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Identification of diseases caused by acid-fast bacilli as background academic context rather than a clinical decision trigger.
The rapid identification of AFB in clinical specimens (e.g., sputum for TB, skin biopsy for leprosy) is a cornerstone of diagnosis.
A positive AFB smear allows for the prompt initiation of specific multi-drug therapy and the implementation of crucial infection control measures, such as respiratory isolation for pulmonary TB, to prevent further spread.
In India, both the National Tuberculosis Elimination Program (NTEP) and the National Leprosy Eradication Programme (NLEP) rely heavily on AFB microscopy for case detection and monitoring treatment response.

How to Approach the Question

This is a factual recall question based on microbiology.
First, analyze the key term: 'Acid-fast bacilli'. Recall or deduce that this refers to a specific staining property of certain bacteria, most notably the Mycobacterium genus.
Next, review the diseases listed in each option and identify their causative agents.
Tuberculosis is caused by Mycobacterium tuberculosis.
Leprosy is caused by Mycobacterium leprae.
SARS is caused by a virus (Coronavirus).

Concept Tested & Keywords

QEnZiZ0GXcOcpOL_ELhNLA

E6 Pathology-Textbook of PATHOLOGYHarsh Mohan Part 1 (1-214) p. 113-115

Practise the full JODHPUR AIIMS SNO-2018

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