A 30-year-old woman was hospitalized after she experienced convulsions. On examination, she was alert and oriented and complained of a fever, headache, and stiff neck. Which of the following is most likely to provide rapid identification of the cause of her symptoms?
A. Check serum antibodies
B. Gram stain of throat culture
C. Biopsy of brain tissue
D. Gram stain of cerebrospinal fluid
E. None of these would provide rapid identification