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New Delhi metallo-β-lactamases (NDMs), including at least 28 variants, are a rapidly emerging family of β-lactamases worldwide, with a variety of infections caused by NDM-positive strains usually associated with very poor prognosis and high mortality. NDMs are the most prevalent carbapenemases in Escherichia coli (E. coli) worldwide, especially in China. The vast majority of blaNDM cases occur on plasmids, which play a vital role in the dissemination of blaNDM. To systematically explore the relationships between plasmids and blaNDM genes in E. coli and obtain an overall picture of the conjugative and mobilizable blaNDM-positive plasmids, we analyzed the variants of blaNDM, replicon types, phylogenetic patterns, conjugative transfer modules, host STs, and geographical distributions of 114 blaNDM-positive plasmids, which were selected from 3786 plasmids from 1346 complete whole genomes of E. coli from the GenBank database. We also established links among the characteristics of blaNDM-positive plasmids in E. coli. Eight variants of blaNDM were found among the 114 blaNDM-positive plasmids, with blaNDM–5 (74 blaNDM–5 genes in 73 plasmids), and blaNDM–1 (31 blaNDM–1 genes in 28 plasmids) being the most dominant. The variant blaNDM–5 was mainly carried by the IncX3 plasmids and IncF plasmids in E. coli, the former were mainly geographically distributed in East Asia (especially in China) and the United States, and the latter were widely distributed worldwide. IncC plasmids were observed to be the predominant carriers of blaNDM–1 genes in E. coli, which were mainly geographically distributed in the United States and China. Other blaNDM–1-carrying plasmids also included IncM2, IncN2, and IncHI1. Moreover, the overall picture of the conjugative and mobilizable blaNDM-positive plasmids in E. coli was described in our study. Our findings enhance our understanding of the genetic diversity and characteristics of blaNDM-positive plasmids in in E. coli.

New Delhi metallo-β-lactamases (NDMs), including at least 28 variants, are a rapidly emerging family of β-lactamases worldwide, with a variety of infections caused by NDM-positive strains usually associated with very poor prognosis and high mortality. NDMs are the most prevalent carbapenemases in Escherichia coli (E. coli) worldwide, especially in China. The vast majority of bla NDM cases occur on plasmids, which play a vital role in the dissemination of bla NDM. To systematically explore the relationships between plasmids and bla NDM genes in E. coli and obtain an overall picture of the conjugative and mobilizable bla NDM-positive plasmids, we analyzed the variants of bla NDM, replicon types, phylogenetic patterns, conjugative transfer modules, host STs, and geographical distributions of 114 bla NDM-positive plasmids, which were selected from 3786 plasmids from 1346 complete whole genomes of E. coli from the GenBank database. We also established links among the characteristics of bla NDM-positive plasmids in E. coli. Eight variants of bla NDM were found among the 114 bla NDM-positive plasmids, with bla NDM–5 (74 bla NDM–5 genes in 73 plasmids), and bla NDM–1 (31 bla NDM–1 genes in 28 plasmids) being the most dominant. The variant bla NDM–5 was mainly carried by the IncX3 plasmids and IncF plasmids in E. coli , the former were mainly geographically distributed in East Asia (especially in China) and the United States, and the latter were widely distributed worldwide. IncC plasmids were observed to be the predominant carriers of bla NDM–1 genes in E. coli , which were mainly geographically distributed in the United States and China. Other bla NDM–1-carrying plasmids also included IncM2, IncN2, and IncHI1. Moreover, the overall picture of the conjugative and mobilizable bla NDM-positive plasmids in E. coli was described in our study. Our findings enhance our understanding of the genetic diversity and characteristics of bla NDM-positive plasmids in in E. coli. [ABSTRACT FROM AUTHOR]

Self-transmissible and mobilizable plasmids contribute to the emergence and spread of multidrug-resistant bacteria by enabling the horizontal transfer of acquired antibiotic resistance. The objective of this study was to capture and characterize self-transmissible and mobilizable resistance plasmids from a coastal wetland impacted by urban stormwater runoff and human wastewater during the rainy season. Four plasmids were captured, two self-transmissible and two mobilizable, using both mating and enrichment approaches. Plasmid genomes, sequenced with either Illumina or PacBio platforms, revealed representatives of incompatibility groups IncP-6, IncR, IncN3, and IncF. The plasmids ranged in size from 36 to 144 kb and encoded known resistance genes for most of the major classes of antibiotics used to treat Gram-negative infections (tetracyclines, sulfonamides, β-lactams, fluoroquinolones, aminoglycosides, and amphenicols). The mobilizable IncP-6 plasmid pLNU-11 was discovered in a strain of Citrobacter freundii enriched from the wetland sediments with tetracycline and nalidixic acid, and encodes a novel AmpC-like β-lactamase (blaWDC-1), which shares less than 62% amino acid sequence identity with the PDC class of β-lactamases found in Pseudomonas aeruginosa. Although the IncR plasmid pTRE-1611 was captured by mating wetland bacteria with P. putida KT2440 as recipient, it was found to be mobilizable rather than self-transmissible. Two self-transmissible multidrug-resistance plasmids were also captured: the small (48 kb) IncN3 plasmid pTRE-131 was captured by mating wetland bacteria with Escherichia coli HY842 where it is seemed to be maintained at nearly 240 copies per cell, while the large (144 kb) IncF plasmid pTRE-2011, which was isolated from a cefotaxime-resistant environmental strain of E. coli ST744, exists at just a single copy per cell. Furthermore, pTRE-2011 bears the globally epidemic blaCTX-M-55 extended-spectrum β-lactamase downstream of ISEcp1. Our results indicate that urban coastal wetlands are reservoirs of diverse self-transmissible and mobilizable plasmids of relevance to human health. [ABSTRACT FROM AUTHOR]