<prompt> An infant had high grade fever and respiratory distress at the time of presentation to the emergency room. The sample collected for blood culture was subsequently positive showing growth of ααα - haemolytic colonies. On Gram staining these were gram positive cocci. In the screening test for identification, the suspected pathogen is likely to be susceptible to the following agent :BacitracinNovobiocinOptochinCloxacillin  <response>: Infant is suffering from pneumococcal pneumonia Gram positive α-hemolytic cocci.Pneumococci is differentiated from other α hemolytic Gram positive cocci by its susceptibility to optochin and bile solubility. 