Molecular epidemiology and population genomics of tet(X4), blaNDM or mcr-1 positive Escherichia coli from migratory birds in southeast coast of China

• Published in: Ecotoxicology and environmental safety 2022-10, Vol.244, p.114032-114032, Article 114032
• Main Authors: Zhang, Wenhui, Lu, Xiaoyu, Chen, Sujuan, Liu, Yuan, Peng, Daxin, Wang, Zhiqiang, Li, Ruichao
• Format: Article
• Language: English
• Subjects: Carbapenem resistance; Colistin resistance; Migratory birds; Tigecycline resistance
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2022.114032

The emergence of multidrug-resistant (MDR) bacteria harboring tet(X4), blaNDM or mcr-1 posed a serious threat to public health. Wild birds, especially migratory birds, were considered as one of important transmission vectors for antibiotic resistance genes (ARGs) globally, however, few studies were performed on the genomic epidemiology of critical resistance genes among them. Isolates harboring tet(X4), mcr-1 or blaNDM from migratory birds were identified and characterized by PCR, antimicrobial susceptibility testing, conjugation assays, whole genome sequencing and bioinformatics analysis. A total of 14 tet(X4)-bearing E. coli, 4 blaNDM-bearing E. coli and 23 mcr-1-bearing E. coli isolates were recovered from 1060 fecal samples of migratory birds. All isolates were MDR bacteria and most plasmids carrying tet(X4), blaNDM or mcr-1 were conjugative. We first identified an E. coli of migratory bird origin carrying blaNDM-4, which was located on a conjugative IncHI2 plasmid and embedded on a novel MDR region flanked by IS26 that could generate the circular intermediate. The emergency of E. coli isolates co-harboring mcr-1 and blaNDM-5 in migratory birds indicated the coexistence of ARGs in migratory birds was a novel threat. This study revealed the prevalence and molecular characteristics of three important ARGs in migratory birds, provided evidence that migratory birds were potential vectors of novel resistance genes and highlighted the monitoring of ARGs in migratory birds should be strengthened to prevent the spread of ARGs in a One Health strategy. [Display omitted] •Genomic epidemiology of MDR E. coli in migratory birds in the East Asian-Australasian Flyway was performed.•Coexistence of mcr-1 and blaNDM-5 in migratory birds was reported.•Novel structure carrying blaNDM-4 in migratory birds was revealed.•Long-distance dissemination of MDR bacteria by migratory birds existed.•ARGs in migratory birds have the potential to transfer to humans.