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: Medicine
Which of the following agent is least likely to cause Meningitis in the elderly? 
Select and explain. 
A. Listeria Monocytogenes, B. Streptococcus pneumonia, C. Gram Negative bacteria, D. Herpes Simplex Virus - 2 (HSV 2)
D: Herpes Simplex Virus - 2 (HSV 2)
Answer: D: Herpes Simplex Virus - 2 (HSV 2) 
Explanation: In elderly, viral meningitis is relatively uncommon. Listeria monocytogenes, streptococcus pneumonia and gram negative bacteria are common causes of meningitis affecting the elderly. So HSV-2 is the single best answer of choice. Ref: Harrison's Principles of Internal Medicine, 16th Edition, Pages 2471-72; Manual of Practical Medicine By R Alagappan, 3rd Edition, Page 524