Infection and Drug Resistance (Aug 2021)
Co-Occurrence of NDM-9 and MCR-1 in a Human Gut Colonized Escherichia coli ST1011
Abstract
Ganfeng Liang,1,* Yuting Rao,2,3,* Shuang Wang,4 Xiaohui Chi,2 Hao Xu,2 Yang Shen1 1Department of Infectious Diseases, The First Hospital of Taizhou, Taizhou, People’s Republic of China; 2Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, People’s Republic of China; 3Department of Laboratory Medicine, Puyang Oil Field General Hospital, Puyang, People’s Republic of China; 4Institute of Bacterial Infection Disease Control, Shandong Centre for Disease Control and Prevention, Jinan, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yang Shen; Hao Xu Email [email protected]; [email protected]: The emergence of the plasmid-borne colistin-resistant gene (mcr-1) poses a great threat to human health. What is worse, the recent observations of the coexistence of mcr-1 with carbapenemase encoding genes in some bacteria caused even more concern. Yet, there is a lack of observations of such strains in the human gut.Methods: The isolation of E. coli L889 was performed on selective medium plates. Antibiotic susceptibilities were determined by an agar dilution and a broth microdilution method. Multi-locus sequence typing (MLST) and acquired resistance genes were also characterized. Transferability of blaNDM-9/mcr-1-carrying plasmids was determined by conjugation, replicon typing and S1-Pulsed-field gel electrophoresis (S1-PFGE), and Southern blotting. The sequences of these plasmids were analyzed by using whole-genome sequencing with Illumina Novaseq and Nanopore platforms.Results: E. coli L889 was identified as ST1101 concomitantly carrying blaNDM-9 and mcr-1 from a stool sample. Antimicrobial susceptibility tests showed that it was resistant to various antimicrobial agents and only susceptible to tigecycline. Notably, blaNDM-9 was located on a ∼ 114-kb untypable plasmid, while mcr-1 was located on a ∼ 63-kb IncI2 plasmid.Conclusion: Our research, to our knowledge, first reported an ST1101 E. coli strain with an untypeable blaNDM-9-harbouring plasmid and an IncI2 mcr-1-carrying plasmid. The colonized E. coli strains potentially contribute to the dissemination and transfer of blaNDM-9 and mcr-1 to clinical isolates, which is a considerable threat to public health and should be closely monitored.Keywords: blaNDM-9, mcr-1, gut, Escherichia coli, ST1101
