Review Question - QID 214717

A 33-year-old woman presents to the emergency department with headache, malaise, and subjective low-grade fever. Her headaches began 1 day ago and are 7/10 in severity. She denies any vision changes, nausea, vomiting, or focal motor or sensory deficits. She recently returned from a hiking trip in Connecticut. She does not have a history of primary headache disorders and reports being otherwise healthy. She takes a multivitamin and has no allergies. Her temperature is 99°F (37.2°C), blood pressure is 135/75 mmHg, pulse is 80/min, and respirations are 16/min. Her body mass index is 30 kg/m^2. The patient is alert to self, location, and year. She is full strength and has a normal sensory examination in all 4 extremities. Kernig and Brudzinski signs are negative. A CT head without contrast is unremarkable. A lumbar puncture is performed, and cerebrospinal fluid results are as follows:

Appearance: Clear
Opening pressure: 280 mm H2O
White blood cells: 95/mm^3
Red blood cells: 76,000/mm^3
Protein: 55 mg/dL
Glucose: 80 mg/dL

There is no evidence of xanthochromia on spectrophotometry. Bacterial, fungal, and acid-fast bacillus culture are pending. Lyme titer and Gram stain are also pending. Which of the following is most likely the cause of this patient’s cerebrospinal fluid results?