<prompt> Which of the following agent is least likely to cause Meningitis in the elderly?Listeria MonocytogenesStreptococcus pneumoniaGram Negative bacteriaHerpes Simplex Virus - 2 HSV 2  <response>: 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: Harrisons Principles of Internal Medicine, 16th Edition, Pages 2471-72; Manual of Practical Medicine By R Alagappan, 3rd Edition, Page 524 