Etiology of septic arthritis in children: an update for the new millennium.

OBJECTIVE: We sought to describe the causative organisms and joints involved in cases of pediatric septic arthritis in the post-Haemophilus influenzae type B and post-pneumococcal vaccine age and in the age of increasing infection with community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA).

METHODS: This was a retrospective chart review of all children younger than 13 years presenting to our tertiary care pediatric emergency department between January 1, 2003, and December 31, 2007, with the diagnosis of septic arthritis. We reviewed the results of synovial fluid Gram stain and synovial fluid and blood culture. We defined septic arthritis as any of these 3 tests being positive for a known pathogen. We report patient characteristics, joint(s) involved, and organisms identified in these cases.

RESULTS: We describe 13 cases of septic arthritis. Fifteen joints were involved. The most common joint involved was the hip (6/15) followed by the elbow (3/15), knee (2/15), and ankle (2/15). The most common organism involved was methicillin-sensitive S aureus (6/13), followed by CA-MRSA (2/13) and Streptococcus pneumoniae (2/13).

CONCLUSION: Our results support continued concern for involvement of the hip and knee in cases of pediatric septic arthritis and consideration of other joints such as the elbow. Our data also suggest that empiric antibiotic coverage for CA-MRSA is indicated in cases of pediatric septic arthritis, as well as continued coverage for methicillin-sensitive S aureus and S pneumoniae.