Spherical-shaped bacteria are called?

Appeared in: DSSSB - 29 August 2019 (Shift-1)

Explanation

Cocci (singular: coccus) are bacteria defined by their spherical or ovoid shape, resembling small berries.
This morphological classification is a primary step in identifying bacteria in a microbiology laboratory, often observed through microscopy after staining.
Cocci are further classified by their arrangement after cell division, such as pairs (diplococci), chains (streptococci), or grape-like clusters (staphylococci), which provides clues to the specific genus.

Option A: Bacilli are characterized by their rod-like or cylindrical shape, not spherical.
Option B: Vibrios are bacteria that have a distinct comma or curved-rod shape, not spherical.
Option C: Spirilla are bacteria with a rigid, spiral or helical shape, which is distinctly different from a spherical shape.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of bacteria based on morphology (shape) as background academic context rather than a clinical decision trigger.
Identifying bacterial shape via Gram staining is a critical first step in diagnosing bacterial infections and guiding initial antibiotic therapy. For instance, a Gram stain showing gram-positive cocci in clusters strongly suggests a Staphylococcal infection.
Knowledge of bacterial morphology helps predict the type of infection and potential complications. For example, Streptococci (chains of cocci) are often associated with strep throat or cellulitis, while Staphylococci (clusters of cocci) are common in skin abscesses.
What if? If a lab report from a wound culture mentions 'gram-positive cocci in chains,' the nurse should anticipate a diagnosis involving a Streptococcus species and prepare for interventions related to conditions like cellulitis or erysipelas, rather than a staphylococcal abscess.

How to Approach the Question

First, identify the key descriptive term in the question stem, which is 'Spherical-shaped'.
Recognize that this is a factual recall question testing fundamental knowledge of microbiology terminology.
Systematically review the definitions of the terms provided in the options.
Recall or deduce the shapes associated with each term: Bacilli (rod), Vibrios (comma), Spirilla (spiral), and Cocci (sphere).
Match the keyword 'Spherical' with the corresponding term, which is 'Cocci', to arrive at the correct answer.

Concept Tested & Keywords

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

E6 Microbiology Essentials Sastry 4e Part 1 p. 35-37

Practise the full DSSSB - 29 August 2019 (Shift-1)

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