Differences between Pneumococcus and Viridans streptococci

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S.N.

Properties

Pneumococcus

Viridans streptococci

1

Morphology

Lanceolate or flame-shaped

Round/oval

2

Arrangement

Gram-positive cocci in pairs

Gram-positive cocci in long chains

3

Capsule

Present

Absent

4

On blood agar

Draughtsman or carom coin colony

Convex shaped colony

5

Liquid medium

Uniform turbidity

Granular turbidity

6

Bile solubility

Soluble in bile

Insoluble in bile

7

Inulin fermentation

Fermenter

Non-fermenter

8

Optochin

Sensitive

Resistant

9

Mice Pathogenicity

Pathogenic

Non-pathogenic

10

Quellung Test

Positive

Negative

11

Hemolysis

Alpha-hemolytic (under aerobic conditions) or Beta-hemolytic (under anaerobic conditions)

Alpha hemolytic or non-hemolytic

12

Pathogenesis

Causes pneumonia

Causes mainly oral infections