An epidemiologic investigation was performed because of a perceived increase in infections caused by community-associated methicillin-resistant Staphylococcus aureus (MRSA) among children in the greater Memphis area.
We reviewed medical records of 289 children evaluated from January 2000 to June 2002 at a children's hospital. Clinical criteria were applied to classify MRSA isolates as community-associated (n=51) or health care-associated (n=138). The relatedness of 33 archived S. aureus isolates was evaluated using pulsed field gel electrophoresis (PFGE) of Sma I-digested genomic DNA; a common pulsed field type was defined as ≥80% similarity based on Dice coefficients. PFGE profiles were compared with those in a national database of MRSA isolates.
During the first 18 study months, 46 of 122 MRSA isolates (38%) were community-associated; this proportion increased to 106 of 167 isolates (63%) during the last 12 study months (P < .0001). Community-associated isolates were recovered from normally sterile sites as frequently as were health care-associated isolates (16% versus 13%). PFGE revealed that 15 of 16 community-associated isolates shared a common pulsed field type (USA300) observed in community-associated MRSA infections elsewhere in the United States and characterized by staphylococcal cassette chromosome mec type IV, clindamycin susceptibility and erythromycin resistance mediated by an msr A-encoded macrolide efflux pump.
Community-associated MRSA has emerged as a potentially invasive pathogen among children in the greater Memphis area, and this phenomenon is not explained by spread of nosocomial strains into the community.
From the *Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN; the †Department of Infection Control, Le Bonheur Children's Medical Center, Memphis, TN; the ‡Division of Healthcare Quality Promotion, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA; and the §Tennessee Department of Health, Nashville, TN
Accepted for publication February 27, 2004.
Presented at the St. Jude/Pediatric Infectious Disease Society Microbial Research Conference, Memphis, TN, February 28–March 1, 2003. Abstract 1.
Reprints not available.