BackgroundThe increasing incidence and prevalence of carbapenem-resistantEnterobacter cloacaecomplex (CREC) poses great challenges to infection prevention and disease treatment. However, much remains unknown about the clinical characteristics of CREC isolates. Our objective was to characterize antimicrobial resistance and, carbapenemase production in CREC with 36 CREC isolates collected from a tertiary hospital in Shandong, China.ResultsThree types of carbapenemases (NDM, IMP and VIM) were detected in these isolates. Among them, NDM carbapenemases were most prevalent, with a 61.2% (22/36) detection rate for NDM-1, 27.8% (10/36) for NDM-5 and 2.8% (1/36) for NDM-7. IMP-4 was found in two isolates and VIM-1 in only one isolate. The MLST analysis identified 12 different sequence types (STs), of which ST171 (27.8%) was the most prevalent, followed by ST418 (25.0%). ST171 isolates had significantly higher rates of resistance than other STs to gentamicin and tobramycin (Ps < 0.05), and lower rates of resistance to aztreonam than ST418 and other STs (Ps< 0.05). Among 17 carbapenemase-encoding genes, theblaNDM−5gene was more frequently detected in ST171 than in ST418 and other isolates (Ps< 0.05). In contrast, theblaNDM−1gene was more frequently seen in ST418 than in ST171 isolates. One novel ST (ST1965) was identified, which carried theblaNDM−1gene.ConclusionNDM-5 produced by ST171 and NDM-1 carbapenemase produced by ST418 were the leading cause of CREC in this hospital. This study enhances the understanding of CREC strains and helps improve infection control and treatment in hospitals.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12866-023-02913-x.