Which of the following data would support a diagnosis of osteomyelitis?

The presence of pyrexia (fever) and an elevated white blood cell count is indicative of an inflammatory or infectious process within the body, which strongly supports a diagnosis of osteomyelitis. Osteomyelitis is an infection in the bone, typically characterized by inflammation, fever, increased white blood cell counts, and other systemic signs of infection.

In cases of osteomyelitis, you would expect to see not only systemic symptoms like fever but also lab results suggesting that the immune system is actively responding to an infection, reflected by an elevated white blood cell count. The combination of these two indicators provides evidence of an ongoing infection that could affect the bone tissues.

In contrast, a negative bone scan would suggest the absence of osteomyelitis, as this imaging technique is sensitive to changes in bone metabolism typically seen in infections. A normal white blood cell count would not align with the diagnosis since one would expect leukocytosis (an increase in white blood cells) in the presence of an infection. Finally, a decreased erythrocyte sedimentation rate would also be atypical, as it usually reflects an active inflammatory process; elevated rates are expected in cases of infection or inflammatory disease.