UC Irvine

Carbapenem-resistant Enterobacteriaceae (CRE) are a rapidly emerging group of multiple drug-resistant organisms (MDROs), with a mortality rate reaching 50\%, causing the CDC to declare them to be the highest level antibiotic-resistant microorganism threat. Drug resistance limits the available treatments for CRE to older, more toxic antibiotics and makes infection control practices to stop the spread of CRE crucial. Because of its dependence on human factors, the spread of MDROs was examined using a newly proposed social ecological model of CRE epidemiology which considered how factors at three levels - the patient, the hospital, and the nursing home - interact throughout inter-facility patient sharing to influence individual patient carriage of MDROs.

The current research began necessary CRE surveillance by quantifying the current prevalence of CRE and identifying targets for intervention in a region in which CRE is still emerging. The results confirm the importance of containing CRE, which had a high mortality rate (31%) and extensive spread (52 days of healthcare facility exposure per year of follow up for CRE carriers). The results also suggest targets for intervention at the intra-personal level, including high comorbidity; and at the institutional levels, highlighting nursing home facilities. The results of statewide studies show that Southern California UC hospitals having 10 times the rate of CRE carriage than Northern California hospitals. Statewide results reaffirmed the high mortality rate and extensive healthcare facility exposure of CRE carriers, which were significantly greater than those of non-CRE carriers. They also emphasized the importance of surveillance definitions in the control of infectious disease and demonstrated how the intra-personal factor of the co-colonization among CRE carriers affects the potential impacts of institutional level contact precautions policies in preventing the spread of emerging MDROs.

Understanding the interplay of factors at the intrapersonal and institutional levels that amplify MDRO spread is important to effectively target interventions, such as contact precautions, to reduce the burden of emerging MDROs. As the population in the United States ages, it will be increasingly important to understand how infection prevention policies at nursing home facilities and healthcare facility exposure contribute to the population burden of infectious disease.