Abstract: Objective To investigate the distribution and drug resistance mechanism of carbapenem-resistantenterobacter(CRE) bacilli in intensive care unit(ICU) patients of a hospital, and to analyze the expression characteristics of New Delhi metallo-β-lactamase 1(NDM-1) gene after rapid detection using polymerase chain reaction(PCR). 
Methods A retrospective analysis was made on 150 ICU patients admitted to Hai′an Hospital of Traditional Chinese Medicine in Jiangsu Province. Automatic microbiological analyzer was used to analyze the detection of CRE in ICU patients. The detection rate of main CRE and the detection situation in each specimen were calculated. The resistance of main CRE strains to antibiotics commonly used in clinical practice was analyzed. The expression characteristics of NDM-1 gene were analyzed by PCR. 
Results A total of 643 strains of enterobacteriaceae were isolated from 150 ICU patients, of which 165 were CRE strains(25.66%). The proportion of Enterobacteriaceae and CRE strains in sputum was the highest(41.06% and 44.85%, respectively). Among 165 strains of CRE isolated, Serratia marcescens was the main strain(26.06%), followed by Klebsiella pneumoniae(23.64%) and Enterobacter cloacis(20.00%). Drug sensitivity results showed that, among 165 CRE strains, tigecycline was the most sensitive(100%), followed by ciprofloxacin(80.00%) and amikacin(74.55%). Among 165 CRE strains, DNM-1 gene was the most abundant, accounting for 58.79%, followed by KPC and VIM, accounting for 23.03% and 18.18%, respectively. 
Conclusion The main strains of CRE in ICU patients in a hospital are Serratia marcescens, Klebsiella pneumoniae and enterobacter cloacei, and they have high resistance to β -lactam antibiotics commonly used in clinical practice, most of which contain NDM-1, further limiting the progress of clinical treatment.

Key words: carbapenem-resistant enterobacteriaceae, polymerase chain reaction, assay, ICU patients