Quantifying the relative impact of contact heterogeneity on MRSA transmission in ICUs - a modelling study

Hao Lei,Rachael M Jones,Yuguo Li

doi:10.1186/s12879-019-4738-0

Abstract

BackgroundAn efficient surface cleaning strategy would first target cleaning to surfaces that make large contributions to the risk of infections.MethodsIn this study, we used data from the literature about methicillin-resistant Staphylococcus aureus (MRSA) and developed an ordinary differential equations based mathematical model to quantify the impact of contact heterogeneity on MRSA transmission in a hypothetical 6-bed intensive care unit (ICU). The susceptible patients are divided into two types, these who are cared by the same nurse as the MRSA infected patient (Type 1) and these who are not (Type 2).ResultsThe results showed that the mean MRSA concentration on three kinds of susceptible patient nearby surfaces was significantly linearly associated with the hand-touch frequency (p < 0.05). The noncompliance of daily cleaning on patient nearby high-touch surfaces (HTSs) had the most impact on MRSA transmission. If the HTSs were not cleaned, the MRSA exposure to Type 1 and 2 susceptible patients would increase 118.4% (standard deviation (SD): 33.0%) and 115.4% (SD: 30.5%) respectively. The communal surfaces (CSs) had the least impact, if CSs were not cleaned, the MRSA exposure to Type 1 susceptible patient would only increase 1.7% (SD: 1.3). The impact of clinical equipment (CE) differed largely for two types of susceptible patients. If the CE was not cleaned, the exposure to Type 1 patients would only increase 8.4% (SD: 3.0%), while for Type 2 patients, it can increase 70.4% (SD: 25.4%).ConclusionsThis study provided a framework to study the pathogen concentration dynamics on environmental surfaces and quantitatively showed the importance of cleaning patient nearby HTSs on controlling the nosocomial infection transmission via contact route.

Highlights

An efficient surface cleaning strategy would first target cleaning to surfaces that make large contributions to the risk of infections
Given the settings we considered in this study, a continuous-time ordinary differential equations (ODEs) based model, developed by Plipat et al [20] and Lei et al [14], was used to simulate the methicillin-resistant Staphylococcus aureus (MRSA) concentration dynamics in different compartments, representing environmental surfaces, patients’ hands, patients’ nares, healthcare workers (HCWs)’ hands and HCWs’ nares
The mean MRSA concentrations at the exposure site of susceptible patient 2 on 7 consecutive days after the index patient was admitted to the intensive care unit (ICU) are 0.17 (SD: 0.058), 0.22 (SD: 0.080), 0.23 (SD: 0.084), 0.23 (SD: 0.084), 0.23 (SD: 0.084), 0.23 (SD: 0.084), and 0.23 (SD: 0.084) CFU/cm2, respectively

Summary

Introduction

An efficient surface cleaning strategy would first target cleaning to surfaces that make large contributions to the risk of infections. HAIs transmission occurs through many processes, including the contact route, in which microorganisms move from surface to surface via contact [2]. An efficient strategy would first target cleaning to surfaces that make large contributions to the risk of HAIs. Studies on the improvement of room hygiene have focused on the high-touch surfaces (HTSs) [6], near patients surfaces [7, 8], or communal locations [9], which were associated with microbial contamination of HCW’s hands. There are few studies (2020) 20:6 that quantitatively evaluate the relative effectiveness of cleaning and disinfecting different surfaces, including HTSs, near-patient surfaces and communal surfaces, on controlling HAIs via the contact route [11]

Methods

Results

Discussion

Conclusion