AUTHOR=Botts Ryan T. , Apffel Brooke A. , Walters C. J. , Davidson Kelly E. , Echols Ryan S. , Geiger Michael R. , Guzman Victoria L. , Haase Victoria S. , Montana Michal A. , La Chat Chip A. , Mielke Jenna A. , Mullen Kelly L. , Virtue Cierra C. , Brown Celeste J. , Top Eva M. , Cummings David E. 

TITLE=Characterization of Four Multidrug Resistance Plasmids Captured from the Sediments of an Urban Coastal Wetland

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.01922

DOI=10.3389/fmicb.2017.01922

ISSN=1664-302X

ABSTRACT=<p>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 <italic>Citrobacter freundii</italic> enriched from the wetland sediments with tetracycline and nalidixic acid, and encodes a novel AmpC-like β-lactamase (<italic>bla</italic><sub><italic>WDC</italic>-1</sub>), which shares less than 62% amino acid sequence identity with the PDC class of β-lactamases found in <italic>Pseudomonas aeruginosa</italic>. Although the IncR plasmid pTRE-1611 was captured by mating wetland bacteria with <italic>P. putida</italic> 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 <italic>Escherichia coli</italic> 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 <italic>E. coli</italic> ST744, exists at just a single copy per cell. Furthermore, pTRE-2011 bears the globally epidemic <italic>bla</italic><sub><italic>CTX-M</italic>-55</sub> extended-spectrum β-lactamase downstream of IS<italic>Ecp1</italic>. Our results indicate that urban coastal wetlands are reservoirs of diverse self-transmissible and mobilizable plasmids of relevance to human health.</p>