Emergence of community-associated methicillin-resistant Staphylococcus aureus at a Memphis, Tennessee Children's Hospital.
BACKGROUND
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.


METHODS
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 > or = 80 % similarity based on Dice coefficients. PFGE profiles were compared with those in a national database of MRSA isolates.


RESULTS
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.


CONCLUSIONS
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.
Buckingham
Steven C
SC
Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, USA.
McDougal
Linda K
LK
Cathey
Lorene D
LD
Comeaux
Katha
K
Craig
Allen S
AS
Fridkin
Scott K
SK
Tenover
Fred C
FC
D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D013714:Tennessee / Q000453:epidemiology