Active screening and Molecular Epidemiology Characteristics of fecal colonization of Carbapenem resistance Enterobacterales from Intensive Care Units wards in a Tertiary Hospital in Shanghai, China

Background: Active screening fecal colonization of carbapenem resistance Enterobacterales (CRE) and intervention in Intensive Care Units(ICU) wards have become important measures to prevent CRE infection. However, limited data is available on molecular epidemiological characteristics and homology analysis of fecal colonization of CRE(CRE-fc) in ICU wards. This prospective observational study was aimed to investigate the molecular epidemiological characteristics and homology analysis of fecal colonization of CRE in ICU wards from a university hospital in China. Methods: Fecal swabs were collected from 435 patients in ICU wards of a tertiary hospital in Shanghai, China from March 1, 2022 to February 28, 2023, and the above specimens were inoculated in Resistant Bacteria Chromogenic Plate (Antu Bio, China). We removed duplicate strains from the same patient and only retain the first isolated CRE-fc. Infection prevention and control (IPC) interventions were carried out for patients with positive CRE screening results. The bacterial identification, antimicrobial susceptibility, MLST and serotypes were profiled. We also applied whole-genome sequencing and core-genome MLST to analysis the molecular epidemiological characteristics and homology of these strains. Results: The prevalence of CRE-fc in ICU wards was 12.6%(55/435). The predominate CRE-fc was Klebsiella pneumoniae (83.6%, 46/55), followed by Escherichia coli (9.1%, 5/55), Enterobacter aerogenes (3.7%, 2/55), Enterobacter cloacae (1.8%, 1/55), Citrobacter freundii (1.8%, 1/55). Through active screening of CRE-fc and IPC interventions in 2022, we found that the CRE infection rate in 2022 (22.8%) was significantly lower than that in 2021 (33.7%). MLST analysis revealed that the 46 fecal colonization of carbapenem resistance Klebsiella pneumoniae (CRKP-fc) belonged to 3 different ST, ST11 was the most predominant ST (71.7%, 33/46), followed by ST15 (26.1%, 12/46) and ST290 (2.2%, 1/46). All ST11 and ST15 strains harbored blaKPC-2, and ten ST15 strains carried two carbapenemase genes (blaKPC-2, blaOXA-1) at the same time. The phylogenetic tree identified two major clades, cluster 1 corresponding to ST11, cluster 2 to ST15. Conclusion: Phylogenetic analysis showed clonal spread of CRKP among patients in ICU wards. ST11-KL64 CRKP has emerged as the most prevalent fecal colonized carbapenem-resistant Enterobacterales and may contribute to hospital outbreaks of infection. Active screening of CRE-fc and IPC interventions can reduce the CRE infection rate in ICU wards.