system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
You are examining the specimen taken from a child with Otitis. On microscopy you see capsulated lanceolate diplococci and the culture of the specimen shows a draughtsman appearance. What is the diagnosis?
assistant
The correct answer is  Pneumococci are gram positive lanceolate diplococci with capsules. When grown on blood agar the colony, assume a dome shape with an area of alpha haemolysis and resembles S.viridans. On fuher incubation the colonies become flat with raised edges and central depression, so that concentric rings are seen on the surface when viewed from above. ie it has carrom coin/ draughtsman appearance. Ref: Textbook of Microbiology by R.Ananthanaraya, Edition 6, Page 201