Modeling the Contact Propagation of Nosocomial Infection in Hospital Emergency Departments Cecilia Jaramillo, Dolores Rexachs and Emilio Luque Computer Architecture and Operating Systems Department Autonomous University of Barcelona Bellaterra/Barcelona, Spain Email: cjaramillo@caos.uab.es, dolores.rexachs@uab.es, emilio.luque@uab.es Francisco Epelde Medicine Department, Hospital Universitari Parc Taul´ ı Autonomous University of Barcelona Sabadell/Barcelona, Spain Email: fepelde@tauli.cat Manel Taboada Tomas Cerda Computer Science School Autonomous University of Barcelona Sant Cugat/Barcelona, Spain. Email: manel.taboada@eug.es Abstract—The nosocomial infection is a special kind of in- fection that is caused by microorganisms acquired inside a hospital. In the daily care process of an emergency department, the interactions between patients and sanitary staff create the environment for the transmission of such microorganisms. Rates of morbility and mortality due to nosocomial infections are important indicators of the quality of hospital work. In this re- search, we use Agent Based Modeling and Simulation techniques to build a model of Methicillin-resistant Staphylococcus Aureus propagation based on an Emergency Department Simulator which has been tested and validated previously. The model obtained will allow us to build a contact propagation simulator that enables the construction of virtual environments with the aim of analyzing how the prevention policies affect the rate of propagation of nosocomial infection. Index Terms—Agent Based Modeling and Simulation; Noso- comial Infection; Hospital Emergency Departments. I. I NTRODUCTION The nosocomial infection is a kind of infection that is caused by microorganisms acquired inside a health care environment. It is the most common type of complication affecting hospi- talized patients. Inside a health care environment we can find several microorganism that can be causative of a nosocomial infection, but our work has focused in the propagation of the Methicillin-resistant Staphylococcus Aureus (MRSA), one of the most common and dangerous microorganisms in this en- vironment. The presence of these bacteria could mean serious health problems for a patient. It is a common cause of skin, wound and, most seriously, blood stream infections as it may be responsible for a greater hospital length of stay, expensive treatments and an increased mortality [1]. MRSA is a bacteria usually resistant to conventional antibiotics that makes it very difficult to treat. These bacteria live in the skin of some patients and could be transmitted to another patient by physical contact through the interaction between patients, healthcare staff and environment. The most common transmission vias are: healthcare staff’s hands, contaminated medical equipment and objects in the hospital room environment. The risk of MRSA acquisition is particularly high in elderly patients, se- vere underlying disease, prolonged hospitalization (especially in ICUs, surgery and burns units), use of invasive medical devices, previous antibiotic treatment and exposure to infected or colonized patients [2]. An emergency department is undoubtedly one of the most complex and dynamic areas in a hospital. Its operation is not linear and depends on several factors. This way, we can conclude that an emergency department can be classified as a complex system. When we work with complex systems, one of the strongest problems is how we can represent human behaviors that cannot be predicted using conventional methods such as qualitative or statistical analysis. Modeling techniques using agents can bring the most benefit when applied to human systems, where agents exhibit complex and stochastic behavior and the interaction between agents are heterogeneous and complex [3]. In our research, we make use of an Agent Based Model and Simulation (ABMS) to create a contact propagation model of MRSA inside a emergency department. For this purpose, we defined all actors involved in the emergency departament process and their specific function and behavior: patients, doctors, nurses, admission staff, laboratory techni- cians, auxiliary personnel and cleaning staff. Every person who has a role in the emergency department is defined as an active agent in our model. It is very important to take into account the environmental objects that healthcare staff use in the process of attention patient because our model is focused on the transmission by contact and this transmission could be between active agents (direct transmission) or between active and passive agents (indirect transmission). Each one of the agents who is interacting in a emergency department can be a multiplier of MRSA bacteria, which depends on the condition of colonized or infected, in the case of active agents, or the condition contaminated in the case of passive agents. In all cases, we apply the term ”transmission vector” to any agent capable of transmitting MRSA bacteria and ”susceptible” to any agent that has risk to adquire the infection. Some health services have implemented concrete actions that attempt to control the rate of propagation of nosocomial 84 Copyright (c) IARIA, 2014. ISBN: 978-1-61208-371-1 SIMUL 2014 : The Sixth International Conference on Advances in System Simulation