MEDizzy - A 65-year-old man is brought to the hospital by his wife

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Infection causing diseases 2

A 65-year-old man is brought to the hospital by his wife because of new-onset fever and confusion. He was well until 3 days ago, when he developed high fever, somnolence, and progressive confusion. His current medical history is unremarkable except for elevated cholesterol, and his only medication is atorvastatin. He is a civil engineer at an international construction company. His wife reports he obtains regular health screening and has always been PPD negative. On admission, his temperature is 40°C, and his vital signs are otherwise normal. He is confused and hallucinating. Soon after admission, he develops a tonic-clonic seizure that requires lorazepam to terminate. His head CT shows no acute bleeding or elevated intracranial pressure. An electroencephalogram shows an epileptiform focus in the left temporal lobe and difusion-weighted magnetic resonance imaging (MRI) shows bilateral temporal lobe infammation. Which of the following is most likely to be diagnostic?

ExplanationIn this scenario, the most likely diagnostic test to perform is: C. CSF PCR for herpes virus The patient's presentation with fever, confusion, hallucinations, and the development of a tonic-clonic seizure is suggestive of viral encephalitis. The imaging findings of bilateral temporal lobe inflammation further support this suspicion. Among the options provided, CSF PCR (polymerase chain reaction) for herpes virus is the most appropriate test for diagnosing viral encephalitis. Herpes simplex virus (HSV) is a common cause of viral encephalitis, and HSV encephalitis often involves the temporal lobes. CSF PCR testing for herpes virus (specifically HSV-1 and HSV-2) can detect viral DNA or RNA in the cerebrospinal fluid, providing a definitive diagnosis. This test is highly sensitive and specific for diagnosing viral encephalitis caused by HSV. The other options are less likely to be diagnostic in this case: A. CSF acid-fast staining: This test is used to detect acid-fast bacilli, typically seen in tuberculosis (TB) meningitis. The clinical presentation and imaging findings in the patient are not suggestive of TB meningitis. B. CSF India ink stain: This test is used to detect the presence of Cryptococcus neoformans, which can cause cryptococcal meningitis. However, the patient's symptoms, seizure, and imaging findings are not consistent with cryptococcal meningitis. D. CSF oligoclonal band testing: This test is used in the evaluation of multiple sclerosis (MS) and other demyelinating diseases. The patient's clinical presentation and imaging findings are not consistent with MS.