This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'After splenectomy, most common infection is \nSelect and explain. \nA. Pneumococcus, B. Escherichia coli, C. Klebsiella, D. Streptococcus', 'role': 'user'}, {'content': "Answer: A \nExplanation: Streptococcus pneumoniae cause infection when host resistance is lowered by contributory factors such as respiratory viral infection, pulmonary congestion, stress, malnutrition, immunodeficiency and alcoholism. Splenectomy and sickle cell disease are impoant predisposing conditions. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 227", 'role': 'assistant'}]