On the epidemiological evolution of colistin-resistant Acinetobacter baumannii in the city of Valencia: an agent-based modelling approach

Antibiotic resistance is one of the greatest public health threats today, mainly due to the non-rational use of antibiotics. Some of these microorganisms, such as Acinetobacter baumannii, which are especially problematic in hospitals, have rapidly developed resistance and only a few last-resort antibiotics, such as colistin, are effective against them. In this work we propose a random agent-based model to describe the evolution of colistin-resistant A. baumannii in the population of Valencia city (Spain) and to predict its impact both on the whole population and by age groups. The model consists of a synthetic population whose agents evolve over time by changing their state variables randomly, based on a set of conditional probabilities, simulating the pathogen infection process. The model has been calibrated with real epidemiological data and, with the best parameters found, simulations and predictions about the incidence and the absolute cases of colistin-resistan A. baumannii have been carried out for the coming years. Results suggest that the evolution of the proportion of resistance will be exponential, exceeding 50% around 2025, and it will affect people over 60 years old more severely in terms of the number of cases.