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  α- 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 :
“Sensitivity to bacitracin is employed as a convenient method for differentiating Str. pyogenes from other hemolytic streptococci.”
Bacitracin
Novobiocin
Optochin
Cloxacillin