Cultural characteristics
|
-
In Nutrient agar plate the colonies are round, smooth, glistening, opaque, low, convex, edge, entire end of a golden yellow or white colour.
-
In nutrient broth an uniform turbidity is present with powdery sediment.
-
Phenolpthaline diphosphate or tellurite agar selectively inhibits non-pathogenic strains.
-
Haemolysis on blood agar. Capable of liberating ‘V’ factor into the medium, which favours the growth of Haemophilus organism.
-
Purple agar, containing bromocresol purple as a pH indicator and 1% maltose, is used to differentiate S. aureus and S. intermedius.
-
Most strains form pigments, hence previously classified as per the colour of the pigment produced.
-
S. aureus – yellowish or golden orange pigment.
-
S. albus - white colonies.
-
S. citreus - lemon yellow colour pigment
-
Later on it was found that pigment formation was variable. Hence such classification was no longer followed.
-
In sheep or rabbit blood agar plate “double haemolysis” around colonies are formed with incubation at 37°C it produces an incomplete haemolysis, which develops into a complete haemolysis when held at 4°C. This is called as hot cold lysis phenomenon.
|
Last modified: Monday, 4 June 2012, 4:14 AM