What is the morphology of Streptococcus?

Morphology. Streptococci are coccoid bacterial cells microscopically, and stain purple (Gram-positive) when Gram staining technique is applied. They are nonmotile and non-spore forming. These cocci measure between 0.5 and 2 μm in diameter.

How does Streptococcus pneumoniae colonize?

Key functions that enable Streptococcus pneumoniae colonization are: establishing the first contact with the epithelium and epithelial receptors, interaction with the complement system, mucus degradation, metal binding, impairment of neutrophil activity and the pro-inflammatory effects of the toxin pneumolysin (Ply).

How is Streptococcus pneumoniae identified?

S. pneumoniae can be identified using Gram stain, catalase, and optochin tests simultaneously, with bile solubility as a confirmatory test. If these tests indicate that the isolate is S. pneumoniae, serological tests to identify the serotype can be performed.

How big are the colonies of Streptococcus pneumoniae?

COLONY MORPHOLOGY: Streptococcus pneumoniae colonies vary in appearance depending on the degree of encapsulation of the organism. Heavily encapsulated strains can have large colonies, several millimeters in diameter, which appear gray and very mucoid, while less heavily encapsulated organisms…

What is the morphology and antigenic structure of Salmonella?

Morphology of Salmonella: 1 Salmonella is Gram Negative rods, measuring 2-4 X 0.6 μm. 2 Non-acid fast 3 Non-capsulated and non-sporing 4 Most serotypes are motile with peritrichous flagella 5 S. galinerum and S. pullorum are non-motile. 6 Most strains of most serotypes produce type-I fimbriae.

How big are Salmonella colonies compared to coliform colonies?

Colonies are large 2-3 mm diameter, circular, low convex and smooth, more translucent than coliform colonies. i. Nutrient Agar (NA) and Blood Agar (BA):

How is Streptococcus pneumoniae differentiated from pneumococci?

Streptococcus pneumoniae bacteria are gram-positive cocci arranged in chains and pairs (diplococci) on microscopic examination. A green, α-hemolytic, zone surrounds S. pneumoniae colonies on blood-agar plates. Pneumococci can be differentiated from other catalase-negative viridans streptococci…

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