The goal of treatment is the prompt recognition of osteomyelitis in the febrile child with bone pain The clinical team should consider advanced imaging by MRI to evaluate for contiguous infections Clinical Considerations Clinical recognition: As the most common bones involved are the femur and tibia, limp is a common presentation The multiplicity of bones that may be involved leads to a wide spectrum of chief complaints Vertebral osteomyelitis manifests as backache, torticollis, or stiff neck, and involvement of the mandible causes painful mastication Infection of the pelvis is particularly elusive and may masquerade as appendicitis, septic hip, neoplasm, or UTI Infants with osteomyelitis localize the symptoms less well than older children Initially, irritability may be the only complaint Fever is seen in 70% to 80% of children with osteomyelitis The infant with a long bone infection often manifests pseudoparalysis, an unwillingness to move the extremity Movement may also be decreased in the older child, but to a lesser degree Point tenderness is seen commonly in osteomyelitis; however, it is nonspecific, as it is found in other conditions, such as trauma, may be difficult to discern in the struggling infant, and does not always occur early in the course of the infection Percussion of a bone at a point remote from the site of an osteomyelitis may elicit pain in the area of infection When purulent material ruptures through the cortex from a subperiosteal abscess, diffuse local erythema and edema appear This finding occurs often in infants, but late in the course, and is confined primarily to children in the first years of life (before the cortex thickens sufficiently to contain the inflammatory exudate) Triage considerations: Any child with fever and a focal bone pain should be evaluated for osteomyelitis Associated tachycardia and/or hypotension can imply sepsis and would require fluid resuscitation Clinical assessment: Bone biopsy cultures are positive in approximately 60% of children with acute hematogenous osteomyelitis, and blood cultures are positive in 50% of cases The ESR and CRP are the most consistent abnormal laboratory studies and can be used to monitor response to therapy Plain radiographs of the affected extremity should be obtained, although they are often normal early in the disease course Within to 10 days, some radiographic anomalies become evident: muscle edema will obliterate the lucent planes separating muscle groups Visualization of bony destruction requires loss of over 40% of the bony matrix, and is a finding uncommon prior to 10 to 14 days MRI is used to evaluate for drainable fluid collections (e.g., subperiosteal abscess or pyomyositis), and the most common finding on MRI in children with osteomyelitis is bone marrow edema In the era of MRSA, many centers have noted that some children with osteomyelitis have infected deep venous thromboses (DVTs) in the adjacent blood vessels MRI also allows for evaluation of DVTs (which appear as flow voids) Recognition of DVTs is important, as it could alter antibiotic therapy (e.g., make it more likely to select a bactericidal antibiotic as opposed to a bacteriostatic drug) and would prompt anticoagulation Management: In contrast to septic arthritis, well-appearing children with suspected osteomyelitis not require immediate parenteral antibiotic therapy If a child has age-appropriate vital signs, is previously healthy, and there is a low likelihood of osteomyelitis, blood cultures and an MRI can be obtained while the child is observed off of antibiotics As blood cultures will be positive in only one-half of children, identification of an organism from bone biopsy is critical The clinician should immediately contact orthopedic surgery or interventional radiology about culturing the infected bone prior to initiation of antibiotics in these patients However, antibiotics should not be withheld if the child becomes or is toxic-appearing or immunocompromised Empiric therapy should target S aureus The selection of vancomycin over clindamycin depends upon local antibiotic susceptibility patterns and any prior culture results available for the child Nafcillin is a more bactericidal drug for MSSA than vancomycin or clindamycin and change to a beta-lactam antibiotic (nafcillin or cefazolin) should occur if the child is known to have MSSA Coverage should be expanded beyond staphylococcal coverage in immunocompromised children, children in whom other pathogens have been cultured in the past, and for septic children Standard precautions should be used Necrotizing Fasciitis Fasciitis is cellulitis extending to deeper tissues, such as fascia and muscle, but not to bones or joints The most common causes in the modern era are GAS and S aureus Widespread use of the varicella vaccine has decreased the incidence of necrotizing fasciitis, where GAS could complicate varicella infection The family may report that the lesion is rapidly progressive Fasciitis can be differentiated from cellulitis by pain out of proportion to examination findings and more systemic signs; toxic appearance, high fever, tachycardia, and hypotension are more common In some cases of anaerobic fasciitis, subcutaneous crepitance may be noted Patients generally have