The Role of Nursing Homes in the Spread of Antimicrobial Resistance Over the Healthcare Network

Abstract

OBJECTIVE Recerntly, the role of the healthcare network, defined as a set of hospitals linked by patient transfers, has been increasingly considered in the control of antimicrobial resistance. Here, we investigate the potential impact of nursing homes on the spread of antimicrobial-resistant pathogens across the healthcare network and its importance for control strategies. METHODS Based on patient transfer data, we designed a network model representing the Dutch healthcare system of hospitals and nursing homes. We simulated the spread of an antimicrobial-resistant pathogen across the healthcare network, and we modeled transmission within institutions using a stochastic susceptible-infected-susceptible (SIS) epidemic model. Transmission between institutions followed transfers. We identified the contribution of nursing homes to the dispersal of the pathogen by comparing simulations of the network with and without nursing homes. RESULTS Our results strongly suggest that nursing homes in the Netherlands have the potential to drive and sustain epidemics across the healthcare network. Even when the daily probability of transmission in nursing homes is much lower than in hospitals, transmission of resistance can be more effective because of the much longer length of stay of patients in nursing homes. CONCLUSIONS If an antimicrobial-resistant pathogen emerges that spreads easily within nursing homes, control efforts aimed at hospitals may no longer be effective in preventing nationwide outbreaks. It is important to consider nursing homes in planning regional and national infection control and in implementing surveillance systems that monitor the spread of antimicrobial resistance. Infect Control Hosp Epidemiol 2016;37:761-767.

FIGURE 1

(a) Map of the Netherlands with the locations of hospitals (blue) and nursing homes (red). (b) Example of the yearly simulated patient flow between 4 of the nursing homes (large red dots) and the hospitals (blue).

FIGURE 2

Prevalence of colonization in simulations on the complete hospital-nursing home network, for 8 different combinations of the transmissibility parameters: (a) β_h=0.25 and β_n=0.005, (b) β_h=0.25 and β_n=0.01, (c) β_h=0.25 and β_n=0.02, (d) β_h=0.25 and βn=0.03, (e) β_h=0.35 and β_n=0.005, (f) β_h=0.35 and β_n=0.01, (g) β_h=0.35 and β_n=0.02, (h) β_h=0.35 and β_n=0.03. The graphs in the first column show the total prevalence of colonization over time for 100 different simulations. The other four graphs show the result of individual simulations. Each line shows the prevalence in either a hospital (green), a nursing home (blue) or the community (per province, black).