Modeling regional transmission and containment of a healthcare-associated multidrug-resistant organism

Abstract

Background. The Centers for Disease Control and Prevention (CDC) recently published interim guidance for a public health response to contain novel or targeted multidrug-resistant organisms (MDROs). We assessed the impact of implementing the strategy in a US state using a mathematical model. Methods. We used a deterministic compartmental model, parametrized via a novel analysis of carbapenem-resistant Enterobacteriaceae data reported to the National Healthcare Safety Network and patient transfer data from the Centers for Medicare and Medicaid Services. The simulations assumed that after the importation of the MDRO and its initial detection by clinical culture at an index hospital, fortnightly prevalence surveys for colonization and additional infection control interventions were implemented at the index facility; similar surveys were then also implemented at those facilities known to be connected most strongly to it as measured by patient transfer data; and prevalence surveys were discontinued after 2 consecutive negative surveys. Results. If additional infection-control interventions are assumed to lead to a 20% reduction in transmissibility in intervention facilities, prevalent case count in the state 3 years after importation would be reduced by 76% (interquartile range: 73-77%). During the third year, these additional infection-control measures would be applied in facilities accounting for 42% (37-46%) of inpatient days. Conclusions. CDC guidance for containing MDROs, when used in combination with information on transfer of patients among hospitals, is predicted to be effective, enabling targeted and efficient use of prevention resources during an outbreak response. Even modestly effective infection-control measures may lead to a substantial reduction in transmission events.