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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
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The most common causative organism causing lobar pneumonia is
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The correct answer is  Although Streptococcus pneumoniae is most common, other organisms must also be considered in light of the patient&;s risk factors and severity of illness.(Ref: Harrison's 18/e p2131)