Which of the following is a flexible, spiral shaped bacteria that has a unique internal flagellar arrangement?

Appeared in: CIP Ranchi 2023

Explanation

Spirochetes are a phylum of bacteria characterized by their long, helically coiled (spiral-shaped) cells.
They are distinguished by their flexibility and a unique mode of motility.
This motility is achieved through specialized flagella, known as axial filaments or endoflagella, which are located within the periplasmic space.
The rotation of these internal filaments causes the entire bacterium to twist and move in a corkscrew-like fashion, allowing it to burrow through viscous media and host tissues.

Option B: Prions are infectious agents composed solely of protein; they are acellular and lack any bacterial structures like flagella.
Option C: Mycoplasma are bacteria that famously lack a cell wall, resulting in a variable (pleomorphic) shape, not a stable spiral. They do not have flagella.
Option D: Bacillus is a genus of bacteria that are characteristically rod-shaped. Motile species possess external flagella, not an internal arrangement.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Bacterial Morphology and Structure as background academic context rather than a clinical decision trigger.
Understanding the unique structure of spirochetes is crucial for diagnosis. For example, their thinness and poor staining with Gram stain require special techniques like dark-field microscopy (for Treponema pallidum) to visualize them.
The corkscrew motility allows spirochetes to invade tissues effectively, which is a key factor in the pathogenesis of diseases like syphilis, Lyme disease, and leptospirosis.
Treatment strategies often target bacterial structures. However, since spirochetes are bacteria, they are susceptible to antibiotics like penicillin, which interfere with cell wall synthesis.

How to Approach the Question

First, break down the question into key descriptive terms: 1) flexible, 2) spiral-shaped, and 3) internal flagellar arrangement.
Evaluate each option against these three criteria.
Recall or deduce the basic characteristics of each option. Prions are proteins, not bacteria, so they are immediately eliminated.
Compare the remaining bacterial options. Mycoplasma lacks a cell wall and a fixed shape. Bacillus is rod-shaped.
Spirochetes are known for their spiral shape and unique endoflagella, which matches all keywords in the question.
Confirm the selection by ensuring it is the only option that fits all parts of the description.

Concept Tested & Keywords

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E6 Microbiology Essentials Sastry 4e Part 1 pp. 84-86, 39-41

E6 Microbiology Applied AnjuDhir 3e Part 1 p. 54-56

Practise the full CIP Ranchi 2023

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