What are the differences between the two strains of Steptococcus pneumoniae?

Question

Accepted Answer

Basis of differentiation

R strain

S strain

Definition

Are a type of bacteria that have rough surfaces and well-defined edges

Are a type of bacteria that have smooth rounded surfaces due to its polysaccharide outer surface

Presence of polysaccharide protective coating

Absent

Present – in addition to its protective function, it gives S bacteria their distinctive smooth appearance

Virulence

Is a nonvirulent strain that does not cause death when injected into a mouse

Is a virulent strain capable of causing death in mice – mice injected with S bacteria developed pneumonia and died

Basis of differentiation	R strain	S strain
Definition	Are a type of bacteria that have rough surfaces and well-defined edges	Are a type of bacteria that have smooth rounded surfaces due to its polysaccharide outer surface
Presence of polysaccharide protective coating	Absent	Present – in addition to its protective function, it gives S bacteria their distinctive smooth appearance
Virulence	Is a nonvirulent strain that does not cause death when injected into a mouse	Is a virulent strain capable of causing death in mice – mice injected with S bacteria developed pneumonia and died