This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'A person from village is complaining of development of pustules. Extract from pus has shown gram positive cocci, showing hemolysis, catalase -ye, identified as a group of streptococci. Following test is used: \nSelect and explain. \nA. Bacitracin sensitivity, B. Novobiocin sensitivity, C. Optochin sensitivity, D. Hemolysis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Bacitracin sensitivity "Sensitivity to bacitracin is employed as a convenient method for differentiating Str. pyogenes from other hemolytic streptococci." Pustule - A vesicle filled with leukocyte. MC cause is virus. MC bacterial cause is Strep. pyogenes. Remember: * Str pyogenes is the etiologic agent in most of the streptococcal skin infection. Vancomycin is the drug of choice. Optochin sensitivity and bile solubility is used to differentiate pneumococci from Strep. viridans group.', 'role': 'assistant'}]