The evolving state of acute pediatric septic arthritis and osteomyelitis

Abstract

Background: A 2006 study from our institution found a 10-fold increase in pediatric community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) osteoarticular infections over a 5-year period and found that these patients had a higher complication rate and required more surgical debridements than those with methicillin-sensitive Staphylococcus aureus (MSSA) infections. Clinical experience since that time has suggested that these trends may have continued. Our investigation sought to evaluate the evolving nature of these infections since the previous publication. Methods: The records of all patients treated at our institution for acute hematogenous septic arthritis and osteomyelitis between January 2005 and December 2011 were reviewed for demographic, diagnostic, clinical, and radiographic data. Results: Of the 240 patients who met the inclusion criteria, 100 were diagnosed with CA-MRSA infections, 51 had MSSA infections, and 75 had no identifiable pathogen. Group A streptococcus (GAS), group B streptococcus (GBS), Streptococcus pneumoniae, and Salmonella were together responsible for 14 infections. The overall infection incidence was 4.29 cases per 1000 hospital admissions. The mean age of CA-MRSA patients was 6.4 yr, compared to 8.9 yr for MSSA patients (P=0.002). There was no significant difference in admission laboratory values, surgical procedures, or long-term complications for CA-MRSA and MSSA infections. Subperiosteal abscess was evident in 51% and 45% of CA-MRSA and MSSA patients, respectively. Surgical intervention was required in 87% of CA-MRSA patients and 84% of MSSA patients. Deep vein thrombosis was identified in 12 CA-MRSA patients, five of whom subsequently developed septic pulmonary emboli. Eight CA-MRSA patients developed chronic osteomyelitis, as did one MSSA patient. Intramuscular abscesses were seen in nine CA-MRSA patients and four MSSA patients. Empiric antibiotic therapy consisted primarily of clindamycin or vancomycin and was tailored according to microbial sensitivities. Conclusions: Contrary to trends identified in an earlier publication, the annual frequency of CA-MRSA infections has stabilized at roughly 40% of all cases. Our data suggest that MSSA infections have become more virulent because these patients now have similar rates of complications and operative interventions to patients with CA-MRSA infections. Level of Evidence: Prognostic level II study (retrospective).