The emergence of highly resistant and hypervirulent <i>Escherichia coli</i> ST405 clone in a tertiary hospital over 8 years

The emergence of carbapenem-resistant <i>Escherichia coli</i> (CREC) poses crucial challenges in clinical management, requiring continuous monitoring to inform control and treatment strategies. This study aimed to investigate the genomic and epidemiological characteristics of CREC isolates obtained from a tertiary hospital in China between 2015 and 2022. Next-generation sequencing was used for genomic profiling, and clinical data from patients were integrated into the analysis. ST405 (21.2%), ST167 (20.3%) and ST410 (15.9%) were the most prevalent of the 30 distinct sequence types (STs) identified among the 113 unique CREC isolates. Infections caused by the ST405 CREC clone and severe underlying diseases were associated with higher in-hospital mortality rates, particularly in patients aged ≥65 years. Furthermore, the ST405 clone exhibited a greater number of virulence and resistance genes than non-ST405 CREC clones. The virulence gene <i>eaeX</i> and resistance genes <i>mph(E)</i> and <i>msr(E)</i> were exclusively found in ST405 clones, while other virulence genes (<i>agn43</i>, <i>ipad</i> and <i>malX</i>) and resistance genes (<i>armA</i>, <i>catB3</i> and <i>arr-3</i>) were more prevalent in this clones. Additionally, ST405 showed higher minimum inhibitory concentrations for both meropenem and imipenem and showed superior growth under the meropenem challenge. <i>Galleria mellonella</i> virulence assays revealed that the ST405 CREC clone was more virulent than other predominant CREC STs. Our findings underscore the clinical threat posed by the ST405 CREC clone, which exhibits both enhanced virulence and extensive drug resistance. These results highlight the urgent need for stringent surveillance and targeted interventions to curb its further dissemination and prevent potential outbreaks.