Community-acquired MRSA infections in North Carolina children: prevalence, antibiotic sensitivities, and risk factors.

Background: The incidence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections in children has increased dramatically over the past decade. CA-MRSA infections are often resistant to standard outpatient antibiotics and present a large burden to the health care system and to afflicted families.

Objectives: Our aims were to characterize the patterns of CA-MRSA resistance to common antibiotics and to identify significant risk factors for CA-MRSA infection in healthy children at a large urban hospital. Additional goals were to discover the prevalence of CA-MRSA in the institution and to observe any notable trends surrounding CA-MRSA infection in the facility.

Methods: We retrospectively analyzed the medical records of patients under 18 years of age in the WakeMed Health and Hospitals system with cultures positive for Staphylococcus aureus over a period of seven and a half months in 2006. Cases were classified as community-acquired, and we then analyzed risk factors and examined trends surrounding CA-MRSA infection.

Results: A total of 229 cases of Staphylococcus aureus infection were identified over the study period, of which 142 were CA-MRSA, a prevalence of 75.9% (95% CI, 69.5-82.3). Our CA-MRSA isolates were 98.6% sensitive to trimethoprim-sulfamethoxasole, 94.4% sensitive to tetracycline, 90.8% sensitive to clindamycin, and 59.9% sensitive to levofloxacin. Risk factors for CA-MRSA infection included parental employment in a school or daycare, family history of boils or MRSA, and antibiotic use by children in the past six months.

Limitations: Our definition of CA-MRSA is based on retrospective data from patient and family verbal histories in the medical record. We did not perform molecular genotyping of MRSA samples to confirm community-associated strains.

Discussion: CA-MRSA is now the predominant strain of Staphylococcus aureus causing childhood infections in this central North Carolina hospital. Thus, standard antibiotic therapy with penicillins or first generation cephalosporins is no longer adequate for most pediatric skin and soft tissue infections in this population. Trimethoprim-sulfamethoxasole and clindamycin both appear as reasonable alternatives for empiric therapy.