Molecular epidemiological characteristics of carbapenem-resistant Enterobacter cloacae complex.

This study aimed to monitor the evolving antibiotic resistance patterns of carbapenem-resistant Enterobacter cloacae complex (CR-ECC) at the Fourth Hospital of Hebei Medical University, characterize the molecular epidemiology through resistance gene profiling and phylogenetic analysis, investigate virulence gene profiles, and establish an evidence-based framework for optimizing clinical antimicrobial therapy and infection control strategies. 32 CR-ECC isolates (2018-2022) underwent Vitek-based identification and susceptibility testing. Carbapenemase production was confirmed by mCIM, with whole-genome sequencing (Illumina) for MLST phylogeny (MEGA/iTOL). Plasmid replicons and resistance/virulence genes were analyzed using PlasmidFinder and RGI/BLAST respectively. CR-ECC emerged in 2020, reaching 32 cases by 2022 as the third most prevalent carbapenem-resistant Enterobacteriaceae. Isolates mainly from sputum (43.75%, 14/32) and blood (25.00%, 8/32), with 53.13% ICU origins. Universal resistance to piperacillin/tazobactam, ceftazidime, imipenem; full susceptibility to tigecycline/colistin. Molecular analysis identified 8 STs, predominantly ST171 (56.25%) carrying blaNDM-1/OXA-1. Plasmid analysis revealed Col(pHAD28)/IncC dominance with ST-specific distribution. Virulence genes showed near-universal fimA/csgD/entB (96.88%) and mrkD (90.63%). These findings highlight the therapeutic potential of tigecycline, colistin, and amikacin against CR-ECC, while emphasizing strain-specific aztreonam susceptibility in metallo-β-lactamase producers.