Modeling the Spread of Methicillin-Resistant Staphylococcus aureus in Nursing Homes for Elderly

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is endemic in many hospital settings, including nursing homes. It is an important nosocomial pathogen that causes mortality and an economic burden to patients, hospitals, and the community. The epidemiology of the bacteria in nursing homes is both hospital- and community-like. Transmission occurs via hands of health care workers (HCWs) and direct contacts among residents during social activities. In this work, mathematical modeling in both deterministic and stochastic frameworks is used to study dissemination of MRSA among residents and HCWs, persistence and prevalence of MRSA in a population, and possible means of controlling the spread of this pathogen in nursing homes. The model predicts that: without strict screening and decolonization of colonized individuals at admission, MRSA may persist; decolonization of colonized residents, improving hand hygiene in both residents and HCWs, reducing the duration of contamination of HCWs, and decreasing the resident∶staff ratio are possible control strategies; the mean time that a resident remains susceptible since admission may be prolonged by screening and decolonization treatment in colonized individuals; in the stochastic framework, the total number of colonized residents varies and may increase when the admission of colonized residents, the duration of colonization, the average number of contacts among residents, or the average number of contacts that each resident requires from HCWs increases; an introduction of a colonized individual into an MRSA-free nursing home has a much higher probability of leading to a major outbreak taking off than an introduction of a contaminated HCW.

Methicillin-resistant Staphylococcus aureus infection in Riveira (Galicia-North West of Spain). Impact of a nursing home MRSA control program on hospital admissions

“…In this sense, a strict screening and decolonization of colonized individuals at admission should be very important. Additionally, improving hand hygiene and environmental cleaning would be useful [25]. In our study, there is a high rate of nursing home residents with positive nasal culture (40.38%) cases.…”

“…Several possible tasks to decrease dissemination of MRSA in nursing homes include strict screening and decolonization of colonized individuals at admission, decolonization of colonized residents and hand hygiene improve of both residents and caregivers [25]. In our study, decolonization of both residents and health workers lead to a diminution in MRSA related hospital admissions by 35% in the year of the intervention in the nursing home (2006) and by 84.7% in 2007, pointing to a very high efficacy of this measure.…”

Optimizing Hospital Infection Control: The Role of Mathematical Modeling

“…These measures targeted HCWs (hand hygiene, staff cohorting, staffing level), 11,17,[19][20][21][22][23] patients (admission colonization, active screening), 9,19,24,25 antibiotic restriction, 24,[26][27][28] or the hospital environment. 21,29 Hand Hygiene, Staff Cohorting, and Staffing Level…”

A hybrid agent-based and differential equations model for simulating antibiotic resistance in a hospital ward

“…By far the most common approach is to model infection dynamics using the so-called SIR models, in which patient (and HCW, if included) populations are divided into categories (compartments), with underlying systems of differential equations describing rates of transition from one category to another, e.g., recent works that focus on control strategies within hospital units (D'Agata et al 2005), facilities other than hospitals (Chamchod and Ruan 2012b), or to suggest coordination at a regional level (Smith et al 2004). One primary drawback of compartmental models is the frequent assumption that each compartment consists of a set of homogeneous individuals.…”