Draughtsman colonies are seen in
(Pneumococcus) (259-P Chakraborty 2nd) (217, 221-Ananthanarayan 7th)* Pneumococci are typically a haemolytic. In prolonged incubation autolysis occurs at central depression (umbonation) of the colony which creates a typical draughtsman or carom coin appearanceDifferentiation between Str. pneumoniae and Strep, viridans Str. pneumoniae Str. viridansMorphologyCapsulated, lanceolate diplococciNoncapsulated, oval or round cells in chainsQuellung testPositive NegativeColoniesInitially dome-shaped later 'draughtsman' colonies Dome shapedGrowth in liquid mediaUniform turbidity Granular turbidityBile solubilityInvariably positive Invariably negativeInulin fermentationPositive NegativeOptochin sensitivityPositive NegativeIntraperitoneal inoculation in miceFatal infection Non pathogenicC. diphtheriaGravis strainsIntermedius strainsMitis strains* Colonies on Telluriteblood Agar* Haemolysis"Daisy head" coloniesin 48-72 hoursVariable"Frog's egg" colonies"Poached egg" coloniesUsually haemolytic Non haemolytic
Staphylococcus
Salmonella
Pneumococcus
Corynebacterium
Bacteria