Epidemiology of and risk factors for infection with extended-spectrum beta-lactamase-producing carbapenem-resistant Enterobacteriaceae: results of a double case-control study Xiaolang Tian,* Shan Sun,* Xiaojiong Jia,* Hua Zou, Shuang Li, Liping Zhang Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, People’s Republic of China *These authors contributed equally to this work Purpose: Carbapenem-resistant Enterobacteriaceae (CRE) have been increasingly reported worldwide and pose a serious public threat, but the clinical significance of extended-spectrum β-lactamase (ESBL) production in CRE is not well established. Patients and methods: A retrospective case–case–control study was conducted to identify the clinical characteristics of patients with ESBL-CRE. The susceptibility of isolates obtained from these patients was assessed. The detection of ESBL and carbapenemase-related genes was performed by PCR methods. Predictors of 30-day mortality in patients with ESBL-CRE infection were also identified in our study. Results: A total of 149 patients with CRE infection caused by Enterobacter cloacae (n