original article Risk Factors for Carbapenemase-Producing Carbapenem-Resistant Enterobacteriaceae (CP-CRE) Acquisition Among Contacts of Newly Diagnosed CP-CRE Patients Anat Schwartz-Neiderman, BSc; 1 Tali Braun, BSc, MHA; 1 Noga Fallach, MA; 1 David Schwartz, PhD; 2 Yehuda Carmeli, MD, MPH; 1,3 Vered Schechner, MD, MSc 1 objective. Carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) are extremely drug-resistant pathogens. Screening of contacts of newly identified CP-CRE patients is an important step to limit further transmission. We aimed to determine the risk factors for CP-CRE acquisition among patients exposed to a CP-CRE index patient. methods. A matched case-control study was performed in a tertiary care hospital in Israel. The study population was comprised of patients who underwent rectal screening for CP-CRE following close contact with a newly identified CP-CRE index patient. Cases were defined as positive tests for CP-CRE. For each case patient, 2 matched controls were randomly selected from the pool of contacts who tested negative for CP-CRE following exposure to the same index case. Bivariate and multivariate analyses were conducted using conditional logistic regression. results. In total, 53 positive contacts were identified in 40 unique investigations (896 tests performed on 735 contacts) between October 6, 2008, and June 7, 2012. bla KPC was the only carbapenemase identified. In multivariate analysis, risk factors for CP-CRE acquisition among contacts were (1) contact with an index patient for ≥3 days (odds ratio [OR], 9.8; 95% confidence interval [CI], 2.0–48.9), (2) mechanical ventilation (OR, 4.1; 95% CI, 1.4–11.9), and (3) carriage or infection with another multidrug-resistant organism (MDRO; OR, 2.6; 95% CI, 1.0–7.1). Among patients who received antibiotics, cephalosporins were associated with a lower risk of acquisition. conclusions. Patient characteristics (ventilation and carriage of another MDRO) as well as duration of contact are risk factors for CP-CRE acquisition among contacts. The role of cephalosporins requires further study. Infect Control Hosp Epidemiol 2016;37:1219 – 1225 The emergence and spread of carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) harboring the gene for Klebsiella pneumoniae carbapenemase (bla KPC ) is a major public health concern. Strains of K. pneumoniae and other Enterobacteriaceae harboring bla KPC are often extremely drug resistant and pose a significant therapeutic challenge. 1,2 Infections by these strains have also been associated with poor clinical outcomes. 3–5 Since they were originally reported in nosocomial outbreaks in the northeastern United States more than a decade ago, these strains have disseminated rapidly to become endemic pathogens in North America, and they are also widespread in Europe, Latin America, and Asia. 6 Israel experienced a large outbreak beginning in 2006, and efforts to contain this outbreak are continuing. 7,8 Data concerning the epidemiology of CP-CRE remain limited. Several case-control studies have identified healthcare-associated factors as predictors for isolation of CP-CRE among hospitalized patients. 3,9,10 Molecular studies have demonstrated how clonal expansion and horizontal plasmid dissemination, either within the same species or, rarely, between species, underlie the spread of these multidrug-resistant pathogens. 11–14 Strict contact isolation, physical separation of carriers from noncarriers, and use of dedicated staff are key components in containing CP-CRE in acute care hospitals. 15 Active surveillance to promptly detect (and isolate) asymptomatic carriers is important measure to curtail transmission to other patients, as clinical cultures detect only a small portion of these carriers. 16,17 In Israel, rectal screening is routinely performed for contacts of newly identified CP-CRE patients. This strategy has also been recommended in international guidelines. 15 However, an explicit definition of who is a contact is lacking. Moreover, risk factors that explain why some contacts of a given index patient acquire CP-CRE and others do not have not yet been elucidated. In this study, we aimed to identify risk factors for acquisition of CP-CRE among patients exposed to an index patient colonized or infected with CP-CRE. Affiliations: 1. Division of Epidemiology and Preventive Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; 2. Laboratory for Clinical Microbiology, Tel-Aviv Sourasky Medical Center, Tel Aviv, Israel; 3. National Center for Infection Control, Israel Ministry of Health, Tel Aviv, Israel. © 2016 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2016/3710-0013. DOI: 10.1017/ice.2016.153 Received February 25, 2016; accepted May 29, 2016; electronically published July 25, 2016 infection control & hospital epidemiology october 2016, vol. 37, no. 10