A 4-Year-Old Boy Is Brought to the Emergency Department by His

A 4-year-old boy is brought to the emergency department by his mother due to refusing to walk since this morning.  The patient started having right groin pain 2 days ago after T-ball practice, and his mother noticed him "walking funny" yesterday.  She says, "I had to carry him here because he says it hurts too much to walk."  The mother has witnessed no recent falls or injuries, and the symptoms have not improved with acetaminophen.  The patient has had upper respiratory symptoms for the last 2 weeks and was diagnosed with viral pharyngitis a week ago.  He has a history of atopic dermatitis that is controlled with low-dose topical corticosteroids.  Immunizations are up to date.  He takes no medications and has no known allergies.  Temperature is 38.6 C (101.5 F) .  The patient appears tired but nontoxic.  The posterior pharynx is clear and without exudates.  The lungs are clear to auscultation.  On examination of the right hip, the patient cries and resists passive movement.  There is decreased range of motion of the right hip.  Dry, erythematous patches are noted on the bilateral forearms.  Laboratory findings show a white blood cell count of 14,000/mm³ and a C-reactive protein of 4.0 mg/L (normal: <3.0 mg/L) . The patient undergoes aspiration of the right hip joint.  Synovial fluid analysis shows a white blood cell count of 60,000/mm³ with a neutrophil predominance.  Gram stain and culture are pending.  Immediate initiation of which of the following therapies is most important to improve the long-term outcome of this patient's condition?

A) Intravenous cefotaxime
B) Intravenous ceftriaxone
C) Intravenous vancomycin
D) Oral naproxen
E) Oral prednisone