A 10-month-old infant is brought to the emergency department for fevers, irritability, and avoidance of motion in the right leg. On physical exam, passive motion of the right hip elicits crying. An AP pelvis and an ultrasound of the right hip are shown in Figures A and B respectively. A hip aspiration yields 82,000 WBC with >80% PMNs. Which of the following is the strongest predictor of a poor prognosis?