When rod shaped bacteria appear in pairs it is known as-

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2024

Explanation

Bacteria are primarily classified based on their shape (morphology) and how they are arranged.
The term 'bacilli' specifically refers to bacteria that are rod-shaped.
The prefix 'diplo-' is used in microbiology to denote an arrangement of cells in pairs.
Combining these terms, 'Diplobacilli' correctly describes rod-shaped bacteria that appear in pairs.

Option B: The prefix 'strepto-' indicates an arrangement in chains, not pairs. This option describes rods in chains.
Option C: The term 'cocci' refers to spherical bacteria, which contradicts the 'rod shaped' description in the question.
Option D: This term describes spherical ('cocci') bacteria arranged in grape-like clusters ('staphylo-'), which is incorrect in both shape and arrangement.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Bacterial morphology and arrangement as background academic context rather than a clinical decision trigger.
Identifying bacterial shape and arrangement via microscopy (like Gram staining) is a fundamental first step in microbiology to presumptively identify pathogens and guide initial antibiotic therapy.
The morphology provides crucial clues. For example, observing Gram-negative diplococci in a urethral smear is highly suggestive of gonorrhea, prompting specific treatment.
What if? If the question had specified 'spherical bacteria in chains,' the correct answer would be Streptococci. This distinction is critical in clinical practice, as infections caused by Streptococcus species (e.g., strep throat) are treated differently from those caused by bacilli.

How to Approach the Question

First, break down the question to identify the key descriptors: 'rod shaped' and 'in pairs'.
Recall the standard microbiological terminology for bacterial shapes. 'Rod shaped' corresponds to 'bacilli'.
Next, recall the prefixes for bacterial arrangement. 'In pairs' corresponds to the prefix 'diplo-'.
Combine the prefix for arrangement ('diplo-') with the term for shape ('bacilli') to get 'Diplobacilli'.
Finally, evaluate the other options to confirm your choice. 'Strepto-' means chains, 'cocci' means spherical, and 'staphylo-' means clusters, confirming that the other options are incorrect.

Concept Tested & Keywords

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

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