What causes diphtheria?

Appeared in: MP CHO - 2022

Explanation

Diphtheria is an acute infectious disease caused by the bacterium Corynebacterium diphtheriae.
Corynebacterium diphtheriae is classified as a bacillus, which is a general term for a rod-shaped bacterium.
The bacteria are Gram-positive, club-shaped, and are known for producing a potent exotoxin.
This exotoxin is responsible for the main clinical features of the disease, including the formation of a gray pseudomembrane in the throat and potential damage to the heart and nerves.

Option A: Diphtheria is caused by a bacterium, not a virus. Viruses are a different class of microorganisms.
Option C: The causative agent of diphtheria is bacterial, not fungal. Fungi are a separate kingdom of organisms.
Option D: A liposome is a non-living, artificial structure used for drug delivery; it is not a pathogenic microorganism.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Causative agent of Diphtheria as background academic context rather than a clinical decision trigger.
Recognizing that diphtheria is caused by a toxin-producing bacterium is critical for nurses to anticipate the need for both antibiotic therapy (to kill the bacteria) and diphtheria antitoxin (to neutralize the toxin).
The presence of a tough, gray pseudomembrane in the pharynx is a hallmark sign that should prompt immediate suspicion of diphtheria and the implementation of strict droplet precautions to prevent transmission.
What if? If a patient presented with a sore throat and easily removable white, curd-like patches, the nurse should suspect a fungal infection like oral candidiasis (thrush), which requires antifungal treatment, rather than the bacterial infection of diphtheria.

How to Approach the Question

This is a factual recall question asking for the causative agent of a specific disease.
First, identify the disease mentioned in the stem: Diphtheria.
Recall or deduce the type of microorganism that causes diphtheria from your knowledge of microbiology and infectious diseases.
Evaluate the given options: Virus, Bacilli (a type of bacteria), Fungus, and Liposome.
Eliminate 'Liposome' immediately, as it is a pharmaceutical term for a drug delivery system, not a pathogen.
Differentiate between the remaining microbial classes. Diphtheria is a classic bacterial disease.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 1 p. 1263-1265

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 164-166

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 369-371

Practise the full MP CHO - 2022

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