Treatment: Antimicrobial therapy for osteomyelitis often is initiated before the diagnosis is confirmed. The risk of delaying treatment for bacteremic patients may be significant, particularly for those with community-associated S. aureus. Cultures should be obtained from blood and suspected foci of infection before initiating empiric antimicrobial therapy. Initial antimicrobial therapy for acute hematogenous osteomyelitis is usually administered parenterally. The empiric regimen is determined by the child’s age, clinical features, and organisms prevalent in the community. The cure rate for osteomyelitis in children is greater than 95%, when the appropriate empiric therapy is chosen.3

Empiric intravenous antimicrobial therapy for infants from birth to age 3 months should be directed against S. aureus, gram-negative bacilli, and group B streptococci, the most common causes of hematogenous osteomyelitis in this age group. 



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Empiric intravenous antimicrobial therapy for children aged older than 3 months should be directed against S. aureus, the most common cause of hematogenous osteomyelitis in this age group, and other gram-positive organisms such as group A streptococci and streptococcal pneumonia. Agents that act against Staphylococcus and Streptococcus include nafcillin, oxacillin, cefazolin, clindamycin, and vancomycin. 


Kingella kingae infection should be considered as a possible pathogen in children aged 6 to 36 months, especially those attending day care and those with indolent osteomyelitis or a history of oral ulcers preceding the onset of musculoskeletal findings. K. kingae infection is usually susceptible to cephalosporin antibiotics but is consistently resistant to vancomycin, and often resistant to clindamycin and anti-staphylococcal penicillins such as nafcillin and oxacillin. 


The antimicrobial regimen can be tailored to a specific pathogen when culture and susceptibility results are available. No organism is identified in approximately 50% of children with suspected osteomyelitis. The decision to continue empiric antibiotic therapy is based on initial clinical suspicion, advanced imaging studies, and response to empiric therapy.6

Surgical intervention may be required at the time of presentation or during antimicrobial therapy if the child fails to respond as expected. Indications for surgical intervention may include drainage of subperiosteal and soft tissue abscess or debridement of contiguous foci of infection.7

Complications: Possible musculoskeletal complications of osteomyelitis vary with age, site of involvement, pathogen, and duration of infection. They include extension of infection into the soft tissue, septic arthritis, abnormal bone growth, pathogenic fracture, collapse of vertebral bodies, chronic osteomyelitis, and venous thrombosis.


Response to therapy: The response to therapy is assessed by serial clinical examination (fever, pain, erythema, and new sites of infection), peripheral leukocyte count, ESR, and/or CRP measurement. The frequency of these evaluations depends on the clinical status of the child. 


Some experts prefer to monitor both ESR and CRP levels in children with acute osteomyelitis. ESR usually increases during the first several days of treatment and then declines slowly in the weeks that follow. CRP level also increases early in the infection but returns to normal range more rapidly than ESR, which makes it more useful in monitoring the course of illness. An increase in CRP level on or after day 4 of treatment may be associated with a complicated clinical course. The peripheral leukocyte count, if initially elevated, usually normalizes within 7 to 10 days after initiation of effective antimicrobial and/or surgical therapy.5

There is no minimum duration of intravenous therapy for treatment of osteomyelitis. Children with uncomplicated osteomyelitis can be switched from intravenous to oral therapy after they have demonstrated clinical improvement, such as no fever for 48 hours, decreased pain and erythema, normalization of leukocyte count, and a 50% reduction in CRP level.8

Current literature suggests administering antimicrobial therapy for 4 weeks or until the ESR and CRP levels normalize, whichever is longer. However, courses of treatment that are longer than 4 weeks may be necessary in children who require surgical debridement or who have delayed clinical improvement, persistent elevation of CRP level, MRSA, or Panton-Valentine leukocidin-positive osteomyelitis (a cytotoxin produced by S. aureus that causes necrotic lesions), or underlying medical conditions.9

Conclusion and follow-up


In this case, Juliet’s mother was concerned that she would not be able to get the drops of oral antibiotic into her infant without spilling; therefore, it was decided early to insert a PICC line. After 4 nights in the hospital, the infant was discharged from the hospital with a schedule of weekly visits by a registered nurse to their home. Intravenous cefazolin, 260 mg every 8 hours via PICC line, was administered for a total of 4 weeks. A complete blood count, basic metabolic panel, ESR, and CRP were measured weekly. 


Her levels normalized quickly. The PICC line was removed and, except for a minor case of contact dermatitis from adhesive tape, the infant had no complications. Juliet made a full recovery and required no follow-up. n


Laura A. Foster, CRNP, FNP, is a family nurse practitioner with Palmetto Primary Care in Charleston, South Carolina.


References


  1. Gustierrez K. Bone and joint infections in children. Pediatr Clin North Am. 2005;52(3):779-794. 

  2. Goergens ED, McEvoy A, Watson M, Barrett IR. Acute osteomyelitis and septic arthritis in children. J Paediatr Child Health. 2005;41(1-2):59-62. 

  3. Dartnell J, Ramachandran M, Katchburian M. Haematogenous acute 
and subacute paediatric osteomyelitis: A systematic review of the literature. J Bone Joint Surg Br. 2012;94(5):584-595.

  4. Pääkkönen M, Kalio MJ, Kallio PE, Peltola H. Sensitivity of erythrocyte sedimentation rate and C-reactive protein in childhood bone and joint infections. Clin Orthop Relat Res. 2010;468(3):861-866. 

  5. Peltola H, Pääkkönen M. Acute osteomyelitis in children. N Engl J Med. 2014;370(4):352. 

  6. Howard-Jones AR, Isaacs D. Systematic review of duration and choice of systemic antibiotic therapy for acute therapy for haematogenous bacterial osteomyelitis in children. J Paediatr Child Health. 2013;49(9):760-768. 

  7. Faust SN, Clark J, Pallett A, Clarke NM. Managing bone and joint infection in children. Arch Dis Child. 2012;97(6):545-553. 

  8. Arnold JC, Cannavino CR, Ross MK, et al. Acute bacterial osteoarticular infections: eight-year analysis of C-reactive protein for oral step-down therapy. Pediatrics. 2012;130(4):821-828.

  9. Peltola H, Pääkkönen M, Kallio P, Kallio MJ; Osteomyelitis-Septic Arthritis Study Group. Short- versus long-term antimicrobial treatment for acute hematogenous osteomyelitis of childhood: Prospective, randomized trial on 131 culture-positive cases. Pediatr Infect Dis J. 2010;29(12):1123-1128.