Risk factors for community-associated methicillin-resistant Staphylococcus aureus cellulitis--and the value of recognition.

Objectives: To identify the risk factors for community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) cellulitis.

Methods: A review of risk factors for CA-MRSA skin and soft tissue infection in previously published literature was first performed. A retrospective cohort study was then conducted in a teaching ambulatory-care clinic of a tertiary medical center in Honolulu, Hawaii.

Results: Of 137 cases with cellulitis diagnosed from January 2005 to December 2007, MRSA was recovered from 85 (62%) of patients who presented with either abscesses or skin ulcers. The recovery of MRSA was significantly associated with obesity (p=0.01), presence of abscesses (p=0.01), and lesions involving the head and neck (p=0.04). Independent risk factors by multivariate logistic regression analysis included the presence of abscesses [adjusted odds ratio (aOR) 2.72; 95% confidence interval (CI) 1.27-5.83; p=0.01] and obesity (aOR 2.33; 95%; CI 1.10-4.97; p%0.03). Patients with CA-MRSA were less likely to receive an appropriate antibiotic (p=0.04) and were more likely to require antibiotic change at evaluation in one week (p=0.04) compared with patients infected with non-MRSA bacteria.

Conclusions: The presence of abscesses and obesity were significantly associated with CA-MRSA cellulitis. Empiric therapy with antibiotics active against MRSA should be guided by these risk factors.