Highly Structured Nurse-to-Patient Interactions in an Acute Care Hospital ICU Reduces MRSA Transmission When Limited to Assigned Patient Groups: A Mathematical Model Approach

Primary Author: Matthew Mietchen

Faculty Sponsor: Eric Lofgen


Primary College/Unit: College of Veterinary Medicine

Category: Medical and Life Sciences

Campus: Pullman




The importance of nurse-to-patient contact in hospital settings for reducing healthcare acquired infections (HAIs) has been well documented. However, it is not well understood how specific interaction patterns effect pathogen transmission. Hospital staffing challenges are a reality, and in addition, are difficult and expensive to study. Using disease transmission models is a useful tool to explore the magnitude and the importance of patient care structure in an intensive care unit (ICU).



A stochastic compartmental model of an 18-bed ICU was used to study how nurse interactions with patients affected the number of methicillin-resistant S. aureus (MRSA) acquisitions. A parameter, gamma, was introduced to represent the proportion of time a nurse spends within an assigned patient sub-group over a one year duration. The model was simulated 10,000 times with gamma being chosen randomly from a uniform distribution within the parameter range. A segmented Poisson regression model was fit to the MRSA acquisitions to detect any relationships or notable change points.



A non-linear relationship was observed, resulting in a decrease in acquisitions as the value of gamma increased. The regression model also detected a single change point in MRSA acquisitions at a gamma value of 0.40 (95% confidence interval: 0.37, 0.42). In conclusion, the proportion of time a nurse spends with an assigned group of patients may have large effects on MRSA transmission within an ICU. Highly structured nurse-to-patient contact with limited interactions outside of assigned patient sub-groups, may be important for hospital epidemiology prevention efforts.