Causes of septic arthritis in the neonatal period

Diagnosis is based on clinical findings, laboratory studies, and joint aspiration. Laboratory tests include peripheral blood studies, which typically demonstrate raised WBC count (> 12,000/mm3) and erythrocyte sedimentation rate (ESR) > 50 mm/hr. Blood cultures are positive in 30% to 50% of cases. The C-reactive protein level is a very good indicator of disease progression. Joint aspiration is essential for diagnosis and typically reveals WBC count > 50,000/mm3. Gram stains of the aspirate are positive in 30% to 50% of the cases while cultures of the aspirate are positive in 50% to 80%.It is imperative to reduce the joint leukocytosis with aspiration or arthrotomy as soon as possible after material has been obtained for gram stain, culture, and sensitivity. Failure to institute early antibiotic therapy and surgical decompression causes the infection to progress and may cause septicemia and increase the likelihood of mortality. The early complications are joint stiffness and subluxation or dislocation of the joint. Involvement of the growth centers cause inhibition of growth, which leads to angular deformities and limb length discrepancy. Long-term follow-up is necessary to detect these conditions and treat them appropriate.The goals of treatment include sterilization and decompression of the joint space and removal of inflammatory debris to relieve pain and prevent deformity or functional sequelae. Surgical drainage and antimicrobial therapy are the cornerstones of therapy.Adequate antibiotic levels in the joint are essential. All antibiotics that have been studied readily enter the joint fluid after systemic administration; intraarticular injection of antibiotics may be unnecessary. The joint fluid concentration of antibiotic averages is 30 percent of the serum concentration at the time of peak serum concentration. In addition, because the efflux of antibiotic from the joint fluid is slow, the joint fluid concentration may exceed serum concentration immediately before the next dose. The antibiotic choice should be adjusted depending on the antibiotic susceptibility patterns of local isolates.