title: The evolving epidemiology of methicillin-resistant Staphylococcus aureus at a university hospital.
abstract: OBJECTIVE
  To describe the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) at a university hospital during a 14-month period.
  
  
  METHODS
  Prospective laboratory-based surveillance for MRSA with descriptive epidemiology based on medical chart review and characterization of strains by DNA typing, using pulsed-field gel electrophoresis (PFGE).
  
  
  METHODS
  An 850-bed tertiary care university hospital.
  
  
  METHODS
  Patients with clinical isolates of MRSA.
  
  
  METHODS
  Determination whether MRSA isolates were community- or hospital-related.
  
  
  RESULTS
  Among 87 patients with MRSA, 36 (41%) had community-acquired infections. Community acquisition was associated with recent hospitalization, previous antibiotic therapy, nursing home residence, and intravenous drug use. Greater than 3 months had elapsed from the time of discharge for 13 (62%) of the 21 patients with community-acquired isolates hospitalized within the last year. Eight patients (22%) with community-acquired MRSA had no discernible risk factors. PFGE allowed differentiation of 35 distinct whole-cell DNA patterns; heterogeneity was seen among both nosocomial and community-acquired isolates, with few instances of cross-transmission.
  
  
  CONCLUSIONS
  Our data suggest an increase in community acquisition of MRSA. PFGE demonstrated heterogeneity of MRSA isolates from both the community and the hospital setting.
authors.affiliation: Department of Medicine, Yale University School of Medicine, New Haven, CT.
authors.forename: M C
authors.initials: MC
authors.lastname: Layton
authors.forename: W J
authors.initials: WJ
authors.lastname: Hierholzer
authors.forename: J E
authors.initials: JE
authors.lastname: Patterson
mesh_terms: D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology*; D003237:Connecticut / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006785:Hospitals, University / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D008297:Male; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D011159:Population Surveillance; D011446:Prospective Studies; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000145:classification / Q000302:isolation & purification*