Special populations (Salmonella spp. (sickle cell disease/hemoglobinopathy) · gram-negatives (neonates/immunocompromised))
First-line therapy
Cefazolin • i.v. • 33–33 mg/kg/dose • 3×/day
Max 2000 mg/dose · Max 6000 mg/day · Duration: 3–6 weeks total · IV until clinical improvement (often 2–7 days) then oral step-down when criteria met; total 3–4 weeks for uncomplicated MSSA and 4–6 weeks for MRSA or complicated disease (PIDS/IDSA-guided)
• Obtain blood cultures and bone aspiration/biopsy for culture before antibiotics when feasible — do not delay antibiotics in unstable/septic child; open biopsy if empiric therapy failing despite appropriate antibiotics and drainage.
• MRI preferred to define extent, subperiosteal abscess, and adjacent joint involvement; plain radiographs for baseline (limited early sensitivity) and follow-up lytic/periosteal changes; ultrasound for guided aspiration and subperiosteal collections.
• Surgical drainage/debridement when subperiosteal abscess, large soft-tissue abscess, neurovascular compromise, or failure to improve within 48–72 h of appropriate antibiotics.
• IV→PO switch when afebrile, pain and weight-bearing improving, hemodynamically stable, tolerating oral therapy, and CRP clearly down-trending.
• Clinical Pearl — suspect BCG osteomyelitis in BCG-vaccinated infants with focal bone pain/swelling weeks to months post-vaccination (often long-bone epiphysis): granulomatous histology/culture; treat with anti-TB therapy per /condition/bcgitis, not empiric cefazolin; early orthopedic and ID consult.
Enter weight on Kids to calculate doses
Cefuroxime • i.v. • 50–50 mg/kg/dose • 3×/day
Max 1500 mg/dose · Max 4500 mg/day · Duration: 3–6 weeks total · Alternative beta-lactam with activity vs Kingella kingae and streptococci; adjust to local susceptibility patterns
• Cefuroxime: suspected Kingella kingae (preschool) when cefazolin not suitable and local susceptibility supports; ensure culture/PCR when available.
• Cephalexin step-down: culture-confirmed MSSA or streptococci with good clinical response to IV therapy and meeting IV→PO criteria.
• Clindamycin step-down: clindamycin-susceptible MRSA (including negative D-test) or beta-lactam allergy; avoid if inducible resistance suspected.
• Neonates (<3 months), sickle cell disease, immunocompromised, penetrating trauma, or healthcare-associated infection: broaden workup and involve ID/orthopedics early; standard regimens may be inadequate.
• Salmonella osteomyelitis (sickle cell): requires culture-guided therapy — often ceftriaxone or fluoroquinolone per susceptibility and local guidance; do not rely on standard anti-staphylococcal empiric therapy alone.
Enter weight on Kids to calculate doses
Clinical notes
• Diagnostics before antibiotics when feasible: blood cultures plus bone aspiration or biopsy for culture when feasible without undue delay; open biopsy if empiric therapy failing; MRI preferred to define bone involvement, subperiosteal abscess, and adjacent septic arthritis; plain radiographs for baseline and follow-up lytic/periosteal changes (limited sensitivity in first 7–10 days); ultrasound for subperiosteal collections and guided aspiration.
• Surgical management: urgent drainage for subperiosteal abscess, large soft-tissue abscess, neurovascular compromise, or failure to improve within 48–72 h of appropriate antibiotics; orthopedic consult at presentation.
• MRSA considerations: add MRSA-active agent (clindamycin if susceptible and child stable; vancomycin if severe illness, bacteremia, or high clindamycin resistance) based on local epidemiology and risk factors; consider Kingella kingae in preschool (6–48 months) with compatible presentation.
• IV→PO switch criteria: improving pain and function, afebrile and clinically stable, tolerating oral medications, reliable follow-up, and CRP clearly down-trending; reassess clinically and with CRP within 48–72 h after switch.
• Duration and follow-up: total 3–4 weeks for uncomplicated MSSA and typically 4–6 weeks for MRSA or complicated disease; monitor clinical response and CRP until normalization or clear downward trend; repeat imaging only for poor response or surgical planning. Clinical Pearl — BCG osteomyelitis: suspect in BCG-vaccinated infants with focal bone pain/swelling weeks to months post-vaccination; confirm with compatible imaging and granulomatous histology/culture; redirect to anti-TB regimen per /condition/bcgitis — standard empiric anti-staphylococcal therapy is inadequate.
• PIDS/IDSA — Clinical Practice Guideline: Acute Hematogenous Osteomyelitis and Septic Arthritis in Children (2021)
• AAP Red Book — Bone and joint infections (S. aureus/MRSA therapy and stewardship principles) (2024)
• ESPID — Pediatric bone and joint infection guidance (Kingella considerations and step-down approach) (2024)
