Which bacterial toxin kills healthy tissues of the respiratory system and forms a grey coating pseudo membran… - RIMS Nursing Officer - 2022

RIMS Nursing Officer - 2022

Microbiology

Easy

Appeared in: RIMS Nursing Officer - 2022

Explanation

Corynebacterium diphtheriae is a bacterium that primarily infects the upper respiratory tract, causing the disease diphtheria.
It produces a potent exotoxin that leads to localized tissue death (necrosis) in the pharynx and larynx.
This process of necrosis and inflammation results in the formation of a characteristic thick, grey, adherent layer known as a pseudomembrane.
The toxin's mechanism involves inhibiting cellular protein synthesis by inactivating Elongation Factor-2 (EF-2), which is fatal to the cell.
This pseudomembrane is the hallmark sign of respiratory diphtheria and can cause life-threatening airway obstruction.

Option A: Mycobacterium tuberculosis primarily affects the lungs, causing tuberculosis. Its hallmark lesion is a granuloma (or tubercle), not a pseudomembrane.
Option B: Helicobacter pylori infects the stomach lining. It is a major cause of gastritis and peptic ulcer disease and does not affect the respiratory system or form pseudomembranes.
Option C: Vibrio cholerae infects the small intestine and causes cholera. Its toxin leads to massive fluid secretion, resulting in severe watery diarrhea (rice-water stools), not a respiratory pseudomembrane.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of Diphtheria as background academic context rather than a clinical decision trigger.
Diphtheria is a vaccine-preventable disease. The DTaP/Tdap vaccine is highly effective, and maintaining up-to-date immunizations is a critical public health measure.
Nurses must recognize that diphtheria is a medical emergency. The primary threat is airway obstruction from the pseudomembrane, requiring immediate intervention and potential airway support.
A key nursing assessment point is to never attempt to scrape or remove the membrane, as this can cause significant bleeding and increase systemic toxin absorption.

How to Approach the Question

First, carefully read the question and identify the key clinical descriptors provided: 'bacterial toxin,' 'respiratory system,' and 'grey coating pseudo membrane.'
Recognize that the formation of a 'grey pseudomembrane' in the respiratory tract is a highly specific, pathognomonic sign of a particular disease.
Systematically evaluate each option against these key features.
Eliminate Mycobacterium tuberculosis, as it is known for causing granulomas in the lungs (tuberculosis).
Eliminate Helicobacter pylori, as it is a gastrointestinal pathogen that affects the stomach.
Eliminate Vibrio cholerae, as it is also a gastrointestinal pathogen that causes severe diarrhea.

Concept Tested & Keywords

Concept Tested: Pathophysiology of Diphtheria
Stem keywords: bacterial toxin, respiratory system, grey coating, pseudo membrane
Lead-in keywords: Which
Negative lead-in flag: false

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