Figure 3.
(a) Time series data showing prevalence of VRE colonization in a 16-bed ICU in Cook County General Hospital, Chicago, showing observed prevalence, with mean and 95% confidence intervals generated by 105 stochastic realizations of the model using parameters shown in Table 1 (dashed lines). LOSs are highly variable, and a mean value is calculated by using the relationship 1/μ = occupancy × beds × study duration/number of patients in study. (b) Two simulated VRE outbreaks in an ICU showing both eradication and endemic stability using the same infection control measures (all parameters are as before). A single VRE-positive patient is admitted on the first day of the outbreak. After 30 days strict infection control measures are implemented (P = 50%). After 45 days a program of cohorting nursing staff with individual patients begins (qn = 64%). After 60 days antibiotic restriction is used to reduce consumption by 50% (α′ = 25%, ξ = 3). However, this intervention proves ineffectual because nosocomial transmission already has been contained. Finally, after 90 days all further VRE-positive admissions are isolated. Other curves indicate the mean cumulative effects of each successive policy for 105 stochastic simulations.