Asymmetric transfer efficiencies between fomites and fingers: Impact on model parameterization.
BACKGROUND
Healthcare-associated infections (HAIs) affect millions of patients every year. Pathogen transmission via fomites and healthcare workers (HCWs) contribute to the persistence of HAIs in hospitals. A critical parameter needed to assess risk of environmental transmission is the pathogen transfer efficiency between fomites and fingers. Recent studies have shown that pathogen transfer is not symmetric. In this study,we evaluated how the commonly used assumption of symmetry in transfer efficiency changes the dynamics of pathogen movement between patients and rooms and the exposures to uncolonized patients.


METHODS
We developed and analyzed a deterministic compartmental model of Acinetobacter baumannii describing the contact-mediated process among HCWs, patients, and the environment. We compared a system using measured asymmetrical transfer efficiency to 2 symmetrical transfer efficiency systems.


RESULTS
Symmetric models consistently overestimated contamination levels on fomites and underestimated contamination on patients and HCWs compared to the asymmetrical model. The magnitudes of these miscalculations can exceed 100%. Regardless of the model, relative percent reductions in contamination declined after hand hygiene compliance reached approximately 60% in the large fomite scenario and 70% in the small fomite scenario.


CONCLUSIONS
This study demonstrates how healthcare facility-specific data can be used for decision-making processes. We show that the incorrect use of transfer efficiency data leads to biased effectiveness estimates for intervention strategies. More accurate exposure models are needed for more informed infection prevention strategies.
['Greene|Christine|C|', 'Ceron|Nancy Hernandez|NH|', 'Eisenberg|Marisa C|MC|', 'Koopman|James|J|', 'Miller|Jesse D|JD|', 'Xi|Chuanwu|C|', 'Eisenberg|Joseph N S|JNS|']
D000151:Acinetobacter Infections D003428:Cross Infection D018562:Disease Transmission, Infectious D004777:Environment D004781:Environmental Exposure D005385:Fingers D050456:Fomites D006268:Health Facilities D006282:Health Personnel D006801:Humans D015233:Models, Statistical D010361:Patients
Transfer efficiency Fomite Parameterization Healthcare-associated infections Environmental transmission Acinetobacter baumannii Hand hygiene Hospital surfaces Mathematical model