Communicable diseases having positive acid fast Bacilli test:

IGNOU PB Bsc Entrance-2023

Applied Microbiology & Infection control

Medium

Appeared in: IGNOU PB Bsc Entrance-2023

Explanation

Tuberculosis and Leprosy are the correct pair as both are caused by bacteria from the Mycobacterium genus.
The causative agent for Tuberculosis is Mycobacterium tuberculosis, and for Leprosy, it is Mycobacterium leprae.
Bacteria of the Mycobacterium genus have a unique cell wall rich in mycolic acid, a waxy substance.
This waxy wall allows the bacteria to retain the primary stain (carbolfuchsin) when treated with an acid-decolorizer, a characteristic known as being 'acid-fast'.
The Acid-Fast Bacilli (AFB) test, such as the Ziehl-Neelsen stain, is specifically designed to identify these organisms.

Option A: Poliomyelitis is caused by a virus (Poliovirus), which is not detected by bacterial staining. Tetanus is caused by Clostridium tetani, a non-acid-fast bacterium.
Option B: Diphtheria is caused by Corynebacterium diphtheriae and Tetanus by Clostridium tetani. Both are Gram-positive bacteria but are not acid-fast.
Option C: While Leprosy is an acid-fast disease, Tetanus is not. Tetanus is caused by Clostridium tetani, a non-acid-fast bacterium.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Identification of diseases based on microbiological staining properties (Acid-Fast Bacilli) as background academic context rather than a clinical decision trigger.
The AFB smear is a rapid, crucial diagnostic tool for presumptive diagnosis of tuberculosis, allowing for prompt initiation of treatment and infection control measures.
Nurses play a vital role in implementing airborne precautions for patients with suspected or confirmed pulmonary TB to prevent transmission within healthcare settings. This includes patient placement in a negative-pressure room and use of N95 respirators.
Patient education on medication adherence is critical for both TB and leprosy, as treatment is long-term and non-compliance can lead to drug resistance and treatment failure.

How to Approach the Question

First, identify the key phrase in the question: 'positive acid fast Bacilli test'.
Recall or deduce the microbiological meaning of 'acid-fast'. This refers to bacteria with a waxy mycolic acid cell wall that resists acid decolorization during staining.
Associate the term 'acid-fast bacilli' with the genus Mycobacterium.
Review the options and identify the diseases caused by Mycobacterium species.
Recognize that Tuberculosis is caused by Mycobacterium tuberculosis and Leprosy is caused by Mycobacterium leprae.
Eliminate other options by identifying their causative agents: Poliomyelitis (virus), Tetanus (Clostridium), and Diphtheria (Corynebacterium), none of which are acid-fast.

Concept Tested & Keywords

Concept Tested: Identification of diseases based on microbiological staining properties (Acid-Fast Bacilli).
Stem keywords: Communicable diseases, positive acid fast Bacilli test
Lead-in keywords: BEST, MOST RELEVANT CLUE

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