title: Modeling the spread of methicillin-resistant Staphylococcus aureus (MRSA) outbreaks throughout the hospitals in Orange County, California.
abstract: BACKGROUND
  Since hospitals in a region often share patients, an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) infection in one hospital could affect other hospitals.
  
  
  METHODS
  Using extensive data collected from Orange County (OC), California, we developed a detailed agent-based model to represent patient movement among all OC hospitals. Experiments simulated MRSA outbreaks in various wards, institutions, and regions. Sensitivity analysis varied lengths of stay, intraward transmission coefficients (β), MRSA loss rate, probability of patient transfer or readmission, and time to readmission.
  
  
  RESULTS
  Each simulated outbreak eventually affected all of the hospitals in the network, with effects depending on the outbreak size and location. Increasing MRSA prevalence at a single hospital (from 5% to 15%) resulted in a 2.9% average increase in relative prevalence at all other hospitals (ranging from no effect to 46.4%). Single-hospital intensive care unit outbreaks (modeled increase from 5% to 15%) caused a 1.4% average relative increase in all other OC hospitals (ranging from no effect to 12.7%).
  
  
  CONCLUSIONS
  MRSA outbreaks may rarely be confined to a single hospital but instead may affect all of the hospitals in a region. This suggests that prevention and control strategies and policies should account for the interconnectedness of health care facilities.
authors.affiliation: University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA. BYL1@pitt.edu
authors.forename: Bruce Y
authors.initials: BY
authors.lastname: Lee
authors.forename: Sarah M
authors.initials: SM
authors.lastname: McGlone
authors.forename: Kim F
authors.initials: KF
authors.lastname: Wong
authors.forename: S Levent
authors.initials: SL
authors.lastname: Yilmaz
authors.forename: Taliser R
authors.initials: TR
authors.lastname: Avery
authors.forename: Yeohan
authors.initials: Y
authors.lastname: Song
authors.forename: Richard
authors.initials: R
authors.lastname: Christie
authors.forename: Stephen
authors.initials: S
authors.lastname: Eubank
authors.forename: Shawn T
authors.initials: ST
authors.lastname: Brown
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Epstein
authors.forename: Jon I
authors.initials: JI
authors.lastname: Parker
authors.forename: Donald S
authors.initials: DS
authors.lastname: Burke
authors.forename: Richard
authors.initials: R
authors.lastname: Platt
authors.forename: Susan S
authors.initials: SS
authors.lastname: Huang
mesh_terms: D002140:California / Q000453:epidemiology; D003198:Computer Simulation; D003428:Cross Infection / Q000453:epidemiology* / Q000635:transmission; D004196:Disease Outbreaks; D004812:Epidemiologic Methods; D006801:Humans; D007902:Length of Stay; D055624:Methicillin-Resistant Staphylococcus aureus; D010359:Patient Readmission; D010360:Patient Transfer; D015995:Prevalence; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000635:transmission; D013997:Time Factors