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

Carline van den Dool,Anja Haenen,Jacco Wallinga,Tjalling Leenstra

doi:10.1017/ice.2016.59

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.

Highlights

The spread of antimicrobial-resistant microorganisms poses an increasing threat to affordable modern health care.[1]
Rigorous control measures exist for MRSA and other highly antimicrobial-resistant microorganisms,[2] in nursing homes, guidelines[12] are less stringent, and compliance with, for example, hand hygiene recommendations is generally low.[13,14,15]
The potential of nursing homes to spread antimicrobial-resistant pathogens has been confirmed by studies in countries with higher levels of these pathogens that have reported a higher prevalence of MRSA in nursing homes than in hospitals[21] and have identified “being transferred from a long-term care institution” as a risk factor for being carrier of MRSA in patients admitted to the hospital.[22]

Summary

Introduction

The spread of antimicrobial-resistant microorganisms poses an increasing threat to affordable modern health care.[1]. An individual could lose colonization at a rate μ, which we chose to be 1/187.5 per day, such that the average duration of colonization was τ = 0.5 year, which is in line with observations of long-term carriage of resistant strains (eg, MRSA and ESBL).[26,27,28] From the parameters β and μ, we calculated RhA and RnA, the basic reproduction numbers for a single admission episode in hospitals and nursing homes, respectively.[29] This admission reproduction number is defined as the average number of new colonizations caused by 1 colonized individual in an entirely susceptible population during 1 admission episode.

Results

Conclusion