摘要
      携带tet（X4）、blaNDM或mcr-1的耐多药（MDR）细菌的出现对公众健康构成了严重威胁。野生鸟类，尤其是候鸟，被认为是全球抗生素抗性基因（ARGs）的重要传播载体之一，但很少对其中关键抗性基因的基因组流行病学进行研究。通过PCR、抗微生物药敏试验、结合分析、全基因组测序和生物信息学分析，鉴定并鉴定了候鸟携带tet（X4）、mcr-1或blaNDM的分离株。从1060份候鸟粪便样本中共分离到14株携带tet（X4）的大肠杆菌、4株携带blaNDM的大肠杆菌和23株携带mcr-1的大肠杆菌。所有分离株均为耐多药细菌，大多数携带tet（X4）、blaNDM或mcr-1的质粒是偶联的。我们首先鉴定了一种携带blaNDM-4的候鸟源大肠杆菌，该大肠杆菌位于偶联的IncHI2质粒上，并嵌入一个新的MDR区域，该区域两侧有IS26，可以产生环状中间体。候鸟中携带mcr-1和blaNDM-5的大肠杆菌分离株的紧急情况表明，候鸟中ARGs的共存是一种新的威胁。这项研究揭示了三种重要ARGs在候鸟中的流行率和分子特征，提供了候鸟是新抗性基因潜在载体的证据，并强调应加强对候鸟ARGs的监测，以在“一个健康”战略中防止ARGs传播。
Abstract
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.

https://www.sciencedirect.com/science/article/pii/S0147651322008727