Li Ru, Wang Junfeng, Zhang Weiting, Zhao Chenhao, Han Mingxiao, Du Hong, Zhang Haifang
Department of Clinical Laboratory, The Nuclear Industry 417 Hospital, Xi'an, China.
Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China.
Curr Microbiol. 2025 Mar 5;82(4):169. doi: 10.1007/s00284-025-04160-x.
Enterobacter hormaechei (E. hormaechei), a member of the Enterobacter cloacae complex, has emerged as an important pathogen in healthcare-associated infections. In this study, a multidrug-resistant E. hormaechei EH001 co-carrying mcr-9 and bla was isolated from a patient with bloodstream infection in China. To investigate the genomic characteristics of a multidrug-resistant E. hormaechei EH001 co-carrying mcr-9 and bla, whole-genome sequencing was employed and conjugation experiment was performed by using the recipient E. coli EC600. The antimicrobial susceptibility profiles of E. hormaechei EH001 revealed resistance to the most commonly used antimicrobial agents, with the exception of polymyxin B, polymyxin E, and minocycline. E. hormaechei EH001 was classified as sequence type 78 (ST78) and harbored multiple resistance genes, especially co-carried mcr-9 and bla located on an IncHI2 plasmid (pMCR9_EH001) and an IncX3 plasmid (pNDM5_EH001), respectively. Both plasmids were successfully co-transferred to E. coli EC600 by conjugation. Analysis of the genetic environment of mcr-9 and bla revealed the multiple mobile genetic elements, such as insertion sequences (IS) and transposon (Tn). ∆Tn3-IS3000-∆ISAba125-5'-IS5-∆ISAba125-3' were situated upstream of bla, while ble-trpF-dsbD-CutA-IS26 were situated downstream of it. In addition, rcnR, rcnA, pcoE, pcoS, and IS5 family transposase (IS903B) were situated upstream of mcr-9, while IS3000 was situated downstream of it, followed by bla and IS26. The majority of the plasmid-mediated resistance genes reside within or adjacent to diverse mobile genetic elements, which may potentially promote the horizontal transfer of antibiotic resistance determinants. This study represents the initial investigation providing the detailed genomic characteristics associated with co-occurrence of mcr-9 and bla in E. hormaechei. The findings advocate for heightened clinical vigilance toward such strains, particularly to prevent nosocomial transmission.
霍氏肠杆菌（E. hormaechei）是阴沟肠杆菌复合体的成员之一，已成为医疗保健相关感染中的一种重要病原体。在本研究中，从中国一名血流感染患者中分离出一株同时携带mcr - 9和bla的多重耐药霍氏肠杆菌EH001。为了研究同时携带mcr - 9和bla的多重耐药霍氏肠杆菌EH001的基因组特征，采用了全基因组测序，并使用受体大肠杆菌EC600进行了接合实验。霍氏肠杆菌EH001的抗菌药物敏感性分析显示，除多粘菌素B、多粘菌素E和米诺环素外，对最常用的抗菌药物均耐药。霍氏肠杆菌EH001被归类为序列型78（ST78），并携带多个耐药基因，特别是分别位于IncHI2质粒（pMCR9_EH001）和IncX3质粒（pNDM5_EH001）上的共携带的mcr - 9和bla。通过接合，这两种质粒都成功地共转移到了大肠杆菌EC600中。对mcr - 9和bla的遗传环境分析揭示了多个可移动遗传元件，如插入序列（IS）和转座子（Tn）。∆Tn3 - IS3000 - ∆ISAba125 - 5'- IS5 - ∆ISAba125 - 3'位于bla的上游，而ble - trpF - dsbD - CutA - IS26位于其下游。此外，rcnR、rcnA、pcoE pcoS和IS5家族转座酶（IS903B）位于mcr - 9的上游，而IS3000位于其下游，随后是bla和IS26。大多数质粒介导的耐药基因位于不同的可移动遗传元件内或附近，这可能潜在地促进抗生素耐药决定簇的水平转移。本研究是对霍氏肠杆菌中mcr - 9和bla共存相关详细基因组特征的初步调查。研究结果提倡对这类菌株提高临床警惕，特别是要防止医院内传播。
