High prevalence of carbapenem-resistant Escherichia coli ST410 from clinical isolates in Weifang, China.

The objective of our work is to identify antimicrobial-resistance genes and to analyze clonality of carbapenem-resistant Escherichia coli. A total of 75 carbapenem-resistant E. coli (CREco) strains were isolated in a Chinese hospital from January 2021 to May 2023. The antibiotic susceptibility testing was conducted by BD PhoenixTM M50 System and Kirby-Bauer disk diffusion method. Whole-genome sequencing was performed on Illumina NovaSeq 6000 platform. Antimicrobial resistance genes were identified based on NCBI with ABRicate 0.8. Multilocus sequence typing (MLST) analysis for CREco was performed. Among the 75 CREco strains in this study, the most of them were isolated from urine samples (n = 20, 26.67%) at the intensive care unit (n = 14, 18.67%). Among the detected carbapenem resistance genes, blaNDM-5 was the most prevalent (n = 57, 76.00%), followed by blaNDM-4 (n = 3, 4.00%), blaNDM-9 (n = 3, 4.00%), and blaNDM-1 (n = 2, 2.67%). In addition, the colistin resistance gene mcr-1.1 (n = 11, 14.67%) and the tigecycline resistance gene tetX4 (n = 2, 2.67%) were also detected. The results of MLST revealed 25 sequence types (STs), and ST410 (n = 17) was the dominant clone. Other major STs included ST167 (n = 12), ST156 (n = 10), ST361 (n = 5), and ST101 (n = 4). Overall, CREco strains exhibited a high-level resistance rate to commonly used antimicrobial agents, and the most of them carried various NDM-coding genes, with blaNDM-5 being the predominant type. In this study, we demonstrated the diversity of carbapenem-resistant E. coli; however, the major clone was ST410. These results also show the dissemination of different clones of carbapenem-resistant E. coli.