Resistance Phenotype and Molecular Epidemiology of Carbapenem-Resistant Isolates in Shanghai.

The emergence and wide global spread of carbapenem-resistant (CRKP) isolates are of great concern, and the aim of this study was to investigate drug resistance, molecular epidemiology, and genetic relationship of CRKP isolates from patients in Shanghai, China. A retrospective study was conducted from April 2018 to July 2019, and a total of 133 CRKP isolates were collected. Antimicrobial susceptibility was determined by VITEK-2 automated microbiology analyzer platform (bioMérieux, France) and the broth microdilution method. Polymerase chain reaction assays were used to investigate the presence of drug resistance genes. A modified carbapenem inactivation method was performed to detect carbapenemases. Multilocus sequence typing and pulsed-field gel electrophoresis (PFGE) were conducted for genetic relatedness of 50 CRKP isolates selected. Among 670 isolates of , 133 (19.9%) strains were identified as CRKP, of which, 76.7% (102/133) strains were isolated from intensive care units (ICUs). All the 133 CRKP isolates were found to be carbapenemase-producers and harbor bla gene. No other carbapenemase genes of , , , and were detected. Furthermore, β-lactamase genes of , , and were the most common resistance-associated genes among these producing isolates. All the 133 CRKP strains displayed >95% of resistance to cephalosporins and carbapenems, except for gentamicin, trimethoprim-sulfamethoxazole, amikacin, tigecycline and colistin, and ceftazidime-avibactam. The most common sequence type was ST11, accounting for 90.0% of the 50 CRKP selected, followed by ST15 (10.0%). PFGE analysis clustered the 50 producing isolates into seven (A-G) distinct clonal clusters at 85% cutoff. Of which, A and G were the two major clusters, accounting for the majority of the strains collected in emergency ICU and neurosurgical ICU. And all the strains of clusters D and E were collected in cardiothoracic surgery ICU, except for one strain collected in one outpatient. The -producing belonged to ST11 was widely disseminated in ICUs, and active and effective surveillance of infection control strategies was initiated to limit the spread of CRKP strains.