A 3-year-old boy is brought by his father to the Emergency Department with fever, headache and neck pain that developed over the past several hours. The father states he is not the birth father, and that he and his wife adopted the boy at 18 months of age after his birth mother abandoned him. Physical examination reveals a lethargic male with a temperature of 39.7 C (103.5 F). There is photophobia, and mildly injected conjunctiva are appreciated. Pupils are equal and reactive and funduscopic examination is unremarkable. The patient has neck stiffness with a positive Kernig's sign. A complete blood count reveals a leukocyte count of 24,000/mm3 with 64 segmented neutrophils and 25 bands. A lumbar puncture is performed that reveals elevated CSF pressure, decreased glucose, and elevated protein. A Gram's stain shows gram-negative pleomorphic rods. There is no growth on blood agar. Growth on chocolate agar reveals white colonies. Which of the following is the most likely pathogen?
A. Haemophilus ducreyi
B. Haemophilus influenzae type b
C. Neisseria meningitidis
D. Listeria monocytogenes
E. Streptococcus pneumoniae