| Condition | Major Pathogens | First-choice Therapy | Alternative Therapy | Comments |
|---|---|---|---|---|
Septic arthritis in child > 3 months old | Staphylococcus aureus Group A streptococcus Kingella kingae in children < 3 years ------------------------ Lyme arthritis is a distinct diagnosis separate from septic arthritis and should be considered in the differential diagnosis | Clinically stable: Cefazolin 50 mg/kg/dose (max 2000 mg/dose) IV q8h ------------------------ Severely ill (hemodynamic instability, multiple sites involved, or known positive blood culture for gram-positive organism): Cefazolin 50 mg/kg/dose (max 2000 mg/dose) IV q8h AND Vancomycin | Penicillin or cephalosporin allergy with higher risk for allergic reaction OR clinically stable with prior MRSA Please confirm clindamycin susceptibility if prior cultures are available Clindamycin 13 mg/kg/dose (max 900 mg/dose) IV q8h | ID and Orthopedic Surgery consults recommended Surgical evaluation is urgent for suspected septic arthritis, particularly hip, knee, or shoulder Send ESR, CRP, and blood culture at initial evaluation |
| Lyme arthritis ANC < 10,000 cells/mm³ AND ESR < 40 mm/hr | Borrelia burgdorferi | Age ≥ 8 yrs: Doxycycline Age < 8 yrs: Amoxicillin | ID consult recommended Duration: 28 days | |
| Bone/joint infection with significant comorbidities, age 0–3 months, penetrating trauma, hardware | Variable |
References:
American Academy of Pediatrics. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. 32nd ed. Elk Grove Village, IL: American Academy of Pediatrics; 2021.
Deanehan JK, et al. Distinguishing Lyme from septic knee monoarthritis in Lyme-disease endemic areas. Pediatrics 2013;131:e695-e701.
Deanehan JK, et al. Synovial fluid findings in children with knee monoarthritis in Lyme disease endemic areas. Pediatr Emerg Care 2014;30:16-19.