MRSA Epidemiology
A retrospective study indicated MRSA was the most common organism in skin abscesses. Moran et al studied a group of ED patients and found that the percentage of SSTIs caused by MRSA increased from 29% (2001 to 2002) to 64% (2003 to 2004). Miller et al discovered that, among their study participates in 2004, 108 (60%) had MRSA infections, and 78 (40%) had methicillin-susceptible Staphylococcus aureus (MSSA) infection.
Furthermore, Moran and colleagues isolated S. aureus from 76% of patients with acute purulent SSTIs presenting to university-affiliated EDs in 11 US cities. They found that MRSA was cultured from 59% of the 422 patients, including 61% of abscesses and 47% of cases of cellulitis with purulent exudates. Winstead et al conducted a 12-month retrospective study of 800 patients in a suburban ED in 2008 and noted that of the 51 (80%) positive cultures, CA-MRSA was isolated from 40 (78%) and Streptococcus from 5 (10%). In a follow-up study to address changing patterns of resistance, Talan et al did a similar study and found that MRSA remained the most common identifiable cause of purulent SSTIs, with an increasing prevalence and decreasing variability between sites. Formerly associated mainly with health care-associated infection, MRSA was now being cultured in patients without previously identified risk factors.