Vancomycin-resistant enterococci colonization-infection model: parameter impacts and outbreak risks

Vancomycin-resistant enterococci (VRE) infections have been linked to increased mortality and costs. A new model of a VRE-infested intensive care unit (ICU) is introduced. It incorporates critical features including the difference between colonization and infection, the role of special preventive care treatment cycles, fitness cost, and antibiotic use. Five patient stages are considered: susceptible, colonized with and without special preventive care, and infected with and without treatment. Parameter ranges are determined representing different ICUs and incorporated to numerically simulate the model. Basic reproductive number of the infection is derived and the impacts of the parameters are analysed. Strategies to minimize VRE infections and outbreak risk are explored with a focus on efficient and simultaneous control of critical parameters. In particular, threshold values of the level of special preventive care and ICU compliance rate are given to achieve desired goals under various constraints.