title: Clinical and economic analysis of methicillin-susceptible and -resistant Staphylococcus aureus infections.
abstract: BACKGROUND
  The rate of methicillin-resistant Staphylococcus aureus (MRSA) has increased significantly over the last decade. Previous cohort studies of patients with MRSA bacteremia have reported higher mortality rates, increased morbidity, longer hospital length of stay (LOS), and higher costs compared with patients with methicillin-susceptible S. aureus (MSSA) bacteremia. The clinical and economic impact of MRSA involving other sites of infection has not been well characterized.
  
  
  OBJECTIVE
  To determine the clinical and economic implications of MRSA compared with MSSA infections across a variety of infection sites and severity of illnesses.
  
  
  METHODS
  A retrospective, case-control analysis comparing differences in clinical and economic outcomes of patients with MRSA and MSSA infections was conducted at an academic medical center. Case patients with MRSA infection were matched (1:1 ratio) to control patients with MSSA infection according to age, site of infection, and type of care.
  
  
  RESULTS
  Thirty-six matched pairs of patients with S. aureus infection were identified. Baseline characteristics of patients with MSSA and MRSA infection were similar. Patients with MRSA infections had a trend toward longer hospital LOS (15.5 vs 11 days; p = 0.05) and longer antibiotic-related LOS (10 vs 7 days; p = 0.003). Median hospital cost associated with treatment of patients with MRSA infections was higher compared with patients with MSSA infections ($16,575 vs $12,862; p = 0.11); however, this difference was not statistically significant. Treatment failure was common in patients with MRSA infection. Among patients with MSSA infections, treatment failure was associated with vancomycin use.
  
  
  CONCLUSIONS
  Patients with MRSA infections had worse clinical and economic outcomes compared with patients with MSSA infections.
authors.affiliation: Adult Critical Care, Department of Pharmacy Practice and Science, College of Pharmacy, University of Arizona, Tucson, AZ 85721-0207, USA. kopp@pharmacy.arizona.edu
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Kopp
authors.forename: David E
authors.initials: DE
authors.lastname: Nix
authors.forename: Edward P
authors.initials: EP
authors.lastname: Armstrong
mesh_terms: D000046:Academic Medical Centers; D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016470:Bacteremia / Q000188:drug therapy / Q000191:economics; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D017048:Health Care Costs; D006801:Humans; D007902:Length of Stay / Q000191:economics; D008297:Male; D008712:Methicillin / Q000627:therapeutic use*; D016106:Methicillin Resistance; D008875:Middle Aged; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000191:economics*; D013211:Staphylococcus aureus; D017211:Treatment Failure; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D008712:Methicillin