P.E. is a 16-year-old male adolescent admitted to the hospital with fever, neck stiffness, and new-onset petechiae. His lumbar puncture in the ED reveals the following: CSF cloudy, WBC 2.5 × 103 cells/mm3 (80 segs, 10 bands, 10 lymphs), glucose 38 mg/dL, and protein 130 mg/dL. He is initially placed on empiric therapy with vancomycin plus ceftriaxone. Twenty-four hours after admission, a Gram stain of the CSF reveals gram-negative cocci.
Which changes would be best to P.E.'s antibiotic regimen, given these culture results?
a. Continue vancomycin and ceftriaxone.
b. Discontinue vancomycin and continue ceftriaxone.
c. Discontinue vancomycin, continue ceftriaxone, and add rifampin.
d. Change ceftriaxone and vancomycin to penicillin and rifampin.