<prompt> A child presents with infective skin lesion of the leg. Culture showed hemolytic colonies which were gram ve cocci in chains. The test to confirm the organism isOptochin sensitivityBile solubilityCatalase positiveBacitracin sensitivity  <response>: Hemolytic colonies with gram-positive cocci in chains suggest either alpha or beta-hemolytic streptococci. Bacitracin sensitivity is used to differentiate between streptococci as follows: Group A: Bacitracin sensitive Group B: Bacitracin resistant Bile solubility and optochin sensitivity are used to differentiate Pneumococcus and Streptococcus viridans Catalase test is used to differentiate Streptococcus and Staphylococcus Reference: Ananthanarayan and Paniker;s Textbook of Microbiology Tenth edition 