title: Acute Bacterial Skin and Skin Structure Infections Treated with Intravenous Antibiotics in the Emergency Department or Observational Unit: Experience at the Detroit Medical Center.
abstract: BACKGROUND
  Acute bacterial skin and skin structure infections (ABSSSIs) are frequently treated in emergency departments (EDs) or observation units (OUs) initially with intravenous (IV) antibiotics before discharge on oral therapy. This study aims to describe ABSSSI patients discharged directly from EDs/OUs.
  
  
  METHODS
  This is a retrospective cohort study of patients with ABSSSIs treated in EDs/OUs of the Detroit Medical Center from 2012 to 2014. Adults with less than 24 h of IV antibiotics without hospital admission were included. Demographics, clinical characteristics, and severity were compared between ED and OU patients. Resource utilization, including tissue and blood cultures, and use of radiographic analysis was also collected. The primary outcome was 96-h ED revisit/hospitalization.
  
  
  RESULTS
  Analysis included 308 patients; 219 ED and 89 OU. OU patients were significantly more likely to be obese, have COPD/asthma, be diagnosed with cellulitis, and meet at least one systemic inflammatory response syndrome (SIRS) criterion. Tissue cultures were obtained in 21.7% of abscesses in the ED; 67.9% were in uncomplicated abscesses. In the OU tissue cultures were obtained in 48.8% of abscesses and 37.5% were uncomplicated cases. Blood cultures were drawn in 18.3% of ED patients and 56.2% of OU patients, not significantly associated with the presence of SIRS criteria. Radiology was used in the diagnosis of ABSSSIs in 33.5% of ED versus 69.5% OU patients (p < 0.001), Plain film radiograph being the most common. Thirty patients revisited the ED or required hospitalization within 96 h, 23 from the ED (p = 0.479). Prior history of ABSSSI (adjusted odds ratio [aOR] = 2.382, 95% confidence interval [CI] 1.264-6.346) and location on torso/buttocks (aOR = 2.355, 95% CI 1.067-5.197) were independent predictors.
  
  
  CONCLUSIONS
  The low rate of ED revisit/hospitalization supports the use of OUs for low acuity ABSSSIs requiring initial IV therapy. Resource utilization within EDs/OUs for the management of ABSSSIs needs to be evaluated for unnecessary testing/procures.
authors.affiliation: Anti-Infective Research Laboratory, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, 48201, USA.
authors.forename: Kimberly C
authors.initials: KC
authors.lastname: Claeys
authors.forename: Abdalhamid M
authors.initials: AM
authors.lastname: Lagnf
authors.forename: Trishna B
authors.initials: TB
authors.lastname: Patel
authors.forename: Manu G
authors.initials: MG
authors.lastname: Jacob
authors.forename: Susan L
authors.initials: SL
authors.lastname: Davis
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rybak