This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Streptococci, Subject name: Microbiology
Streptococcus pyogenes can be checked by which drug disk 
Select and explain. 
A. Bacitracin, B. Polymycin, C. Optochin, D. None of the above
A: Bacitracin
Answer: A: Bacitracin 
Explanation: Ans. (a) BacitracinRef.: Microbiology by Ananthanarayan and Paniker 8th ed. /201, 206-07, 2012* The various species of Streptococcus can be checked by various drug disks which is indicated as whether it is sensitive or resistant to the drug.* S. pyogenes is bacitracin sensitive.* S. agalactiae is bacitracin resistant.* S. pneumoniae is inhibited by optochin.* S. viridans is not inhibited by optochin.