This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
[{'content': 'Which is the most common contaminant in a positive blood culture \nSelect and explain. \nA. Staphylococcus epidermidis, B. Bacteriodes, C. Candida, D. Aceinobacter', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Staphylococcus epidermidis is the most common contaminant in positive blood culture among the given bacteria. Ref ananthnarayana and panikers microbiology textbook 8/e', 'role': 'assistant'}]