MRSA Rates and Antibiotic Susceptibilities from Skin and Soft Tissue Cultures in a Suburban ED

BackgroundPrior studies suggest that more than half of all skin and soft tissue infections (SSTIs) are caused by methicillin-resistant Staphylococcus aureus (MRSA). These data mainly represent inner-city urban centers.ObjectiveWe determined the bacteriologic etiologies and antibiotic susceptibilities from wound cultures in the emergency department (ED). We hypothesized that in a suburban ED, MRSA would not represent the major pathogen.MethodsThe study design was a retrospective, electronic medical record review in a suburban tertiary care ED with 80,000 annual visits. Subjects included ED patients of all ages who had skin or soft tissue cultures obtained in 2005–2008. Demographics and clinical data, including type of SSTI (MRSA or methicillin-sensitive S. aureus [MSSA]), culture results, and antibiotic susceptibility, were analyzed using descriptive statistics.ResultsFrom the 1246 cultures obtained during the study period, 252 (20.2%) were MSSA and 270 (21.6%) were MRSA. The rates of MRSA infections over time increased from 13.5% to 25.7% during 2005–2008. The rates of MRSA in males and females were comparable at 23.3% and 19.6%, respectively. In 2008, MRSA was 97–100% susceptible to vancomycin, linezolid, rifampin, nitrofurantoin, chloramphenicol, gentamycin, tetracycline, and trimethoprim-sulfamethoxazole (TMP-SMZ). To a lesser extent it was susceptible to clindamycin (75%), erythromycin (62%), and levofloxacin (50%).ConclusionsThere has been a significant increase in the rates of MRSA SSTIs in a suburban ED, yet only 1 in 4 SSTIs are caused by MRSA. Both MRSA and MSSA are completely susceptible to vancomycin, linezolid, rifampin, nitrofurantoin, and chloramphenicol. Gentamicin, tetracycline, and TMP-SMZ cover > 97% of both isolates.