Differentiating between methicillin-resistant and methicillin-sensitive Staphylococcus aureus osteomyelitis in...

Area of Science:

• Pediatric infectious diseases
• Orthopedic surgery
• Clinical microbiology

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) causes more virulent osteomyelitis than methicillin-sensitive Staphylococcus aureus (MSSA).
• Clinical differentiation between MRSA and MSSA osteomyelitis is challenging but crucial for appropriate treatment.
• Early diagnosis of MRSA osteomyelitis is essential to prevent complications.

Purpose of the Study:

• To develop a clinical prediction algorithm for distinguishing MRSA from MSSA osteomyelitis in children.
• To identify independent predictors of MRSA osteomyelitis in pediatric patients.

Main Methods:

• Retrospective review of 129 children with culture-proven Staphylococcus aureus osteomyelitis (2000-2009).
• Comparison of demographics, symptoms, vital signs, and lab values between MRSA and MSSA groups.
• Multivariate logistic regression and receiver operating characteristic (ROC) curve analysis to identify predictors and optimal cutoffs.

Main Results:

• Significant differences observed between MRSA and MSSA groups in non-weight-bearing status, prior antibiotic use, temperature, hematocrit, heart rate, WBC count, platelet count, CRP, and ESR.
• Four independent predictors identified: temperature >38°C, hematocrit <34%, WBC count >12,000/µL, and CRP >13 mg/L.
• Algorithm achieved 92% predicted probability of MRSA with all four predictors; ROC analysis showed an area under the curve of 0.94.

Conclusions:

• The four-predictor algorithm demonstrates excellent diagnostic performance for differentiating pediatric MRSA from MSSA osteomyelitis.
• This tool can guide patient management and facilitate prompt, appropriate antibiotic selection.
• Early identification of MRSA osteomyelitis improves clinical outcomes and antibiotic stewardship.