703. Epidemiology of Skin and Soft Tissue Infections in the Ambulatory Care Setting of an Urban Healthcare System
Session: Poster Abstract Session: Skin, Soft Tissue and Joint Infections
Friday, October 21, 2011
Room: Poster Hall B1

Background:  The epidemiology of skin and soft tissue infection (SSTI) has changed with the emergence of community-associated methicillin-resistant Staphylococcus aureus (MRSA).  The purpose of this study was to describe the temporal trends and clinical spectrum of SSTI in the ambulatory care setting of an integrated healthcare system.

Methods:  Using ICD-9 coding data, we identified adults and children with a primary diagnosis of SSTI from urgent care, emergency department, or outpatient clinic encounters between January 1, 2005 and December 31, 2010.  We performed a retrospective cohort study on a random sample of cases between March 1, 2010 and February 28, 2011 and classified infections as uncomplicated cellulitis, wound infection, cutaneous abscess, or SSTI with complicating factors including bites, diabetic or vascular ulcers, periorbital or perineal involvement, peripheral arterial disease, and recurrent infection. 

Results:  From 2005 to 2010, there was a distinct seasonality of clinical encounters for SSTI, with visits being more common in summer months than non-summer months (p = .035) (Figure). 

This seasonality was evident when the data were stratified into adult and pediatric populations.  Of 670 cases reviewed for the retrospective cohort study, 428 met criteria for inclusion: 148 (35%) were uncomplicated cellulitis, 41 (10%) wound infections, 167 (39%) abscesses, and 72 (17%) involved complicating factors.  Nearly all visits occurred in the urgent care center (189, 44%), primary care clinics (126, 29%), or emergency department (105, 25%).  Prior skin infection (105, 25%), alcohol dependence (69, 16%), and diabetes mellitus (56, 13%) were common risk factors.  211 (49%) patients did not have a predisposing comorbid condition or risk factor for SSTI.  In total, staphylococci or streptococci were identified in 73 of 76 (96%) cases with a positive culture; MRSA was identified in 27 (36%). 

Conclusion:  Skin and soft tissue infections exhibit a seasonal pattern and are more frequent in summer months.  Urgent care and primary care clinics are common sites of presentation.  Uncomplicated abscesses comprise a minority of all skin infections in the ambulatory care setting. 


Subject Category: C. Clinical studies of bacterial infections and antibacterials including sexually transmitted diseases and mycobacterial infections (surveys, epidemiology, and clinical trials)

Timothy Jenkins, MD1, Hermione Hurley, MBChB2, Bryan Knepper, MPH, MSc1, Claire Swartwood, PharmD1, Connie Price, MD1, Philip Mehler, MD1 and William Burman, MD1, (1)Denver Health Medical Center, Denver, CO, (2)Exempla St. Joseph Hospital, Denver, CO

Disclosures:

T. Jenkins, None

H. Hurley, None

B. Knepper, None

C. Swartwood, None

C. Price, None

P. Mehler, None

W. Burman, None

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