For each of the following patient descriptions, select the most likely infectious agent involving the central nervous system to produce the Ūndings:

1. A 72-year-old man presents with bilateral decreased sensation in his lower extremities. He is noted to have a widened gait. He exhibits psychotic behavior. While in an extended care facility, he succumbs to complications of congestive heart failure from aortic valvular insufficiency. At autopsy there is meningeal thickening and cortical atrophy. Microscopically the meninges exhibit a mononuclear infiltrate, including many plasma cells. The underlying cerebral cortex demonstrates neuronal loss and microglial rod cells. An endaortitis is seen in the aortic wall:

2. A 50-year-old woman with chronic headaches has a head CT scan that reveals enlargement of the cerebral ventricles. By MR imaging there is cerebral cortical thinning, and there is meningeal thickening with several small 1 cm nodules at the base of the brain. A chest radiograph reveals bilateral upper lobe calcification and cavitation of the lungs:

3. An 80-year-old man has had a constant headache for the past 2 days. On examination he is febrile. A lumbar puncture is performed and the opening pressure is slightly increased, with cloudy cerebrospinal fluid. The CSF cell count shows increased WBCs, mostly neutrophils, markedly decreased glucose, and slightly increased protein:

4. A 32-year-old HIV positive man has had a headache for the past 3 days. On examination he has nuchal rigidity. A lumbar puncture is performed and the WBC count is increased with a mixture of leukocytes. There are organisms seen with India ink preparation:

5. A 28-year-old woman has sudden onset of a seizure. On examination she is febrile and delirious. CT imaging shows bilateral temporal lobe hemorrhages:

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A. Acanthamoeba B. Aspergillus fumigatus C. Cryptococcus neoformans D. Cytomegalovirus
E. Herpes simplex virus F. Human immunodeficiency virus G. J-C polyomaavirus H. Mycobacterium tuberculosis
I. Streptococcus pneumoniae J. Treponema pallidum K. Toxoplasma gondii L. Venezuelan equine encephalitis virus


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