A 44-year-old man is brought to the emergency department by his wife because of confusion that began a few hours ago. Earlier in the day, he complained of a severe headache and nausea. On physical examination, his temperature is 38.3 C (101 F) and nuchal rigidity is present. Lumbar puncture and cerebrospinal fluid (CSF) examination show:Opening pressure300 mm H2OGlucose20 mg/dLProtein200 mg/dLRBCs4 cells/µLLeukocytes760 cells/µL Neutrophils90% Lymphocytes10%Gram stain of the CSF would most likely reveal which of the following?