AUTHOR=Zhang Li-Juan , Gu Xi-Xi , Zhang Jie , Yang Ling , Lu Yue-Wei , Fang Liang-Xing , Jiang Hong-Xia 

TITLE=Characterization of a fosA3 Carrying IncC–IncN Plasmid From a Multidrug-Resistant ST17 Salmonella Indiana Isolate

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01582

DOI=10.3389/fmicb.2020.01582

ISSN=1664-302X

ABSTRACT=<p>The aim of this study was to investigate the characteristics of a <italic>fosA3</italic> carrying IncC–IncN plasmid from a multidrug-resistant <italic>Salmonella</italic> isolate HNK130. HNK130 was isolated from a chicken and identified as ST17 <italic>Salmonella enterica</italic> serovar Indiana and exhibited resistance to 13 antibiotics including the cephalosporins and fosfomycin. S1 nuclease pulsed-field gel electrophoresis and Southern blot assays revealed that HNK130 harbored only one ∼180-kb plasmid carrying <italic>fosA3</italic> and <italic>bla</italic><sub>CTX–M–14</sub>, which was not transferable via conjugation. We further examined 107 <italic>Escherichia coli</italic> electro-transformants and identified 3 different plasmid variants, pT-HNK130-1 (69), pT-HNK130-2 (15), and pT-HNK130-3 (23), in which pT-HNK130-1 seemed to be the same as the plasmid harbored in HNK130. We completely sequenced an example of each of these variants, and all three variants were IncC–IncN multi-incompatible plasmid and showed a mosaic structure. The <italic>fosA3</italic> gene was present in all three and bounded by IS<italic>26</italic> elements in the same orientation (IS<italic>26</italic>-322bp-<italic>fosA3</italic>-1758bp-IS<italic>26</italic>) that could form a minicircle containing <italic>fosA3</italic>. The <italic>bla</italic><sub>CTX–M–14</sub> gene was located within an IS<italic>15DI-</italic>ΔIS<italic>15DI-iroN-</italic>IS<italic>903B-bla</italic><sub>CTX–M–14</sub><italic>-</italic>ΔIS<italic>Ecp1-</italic>IS<italic>26</italic> structure separated from the <italic>fosA3</italic> gene in pT-HNK130-1, but was adjacent to <italic>fosA3</italic> in pT-HNK130-3 in an inverted orientation. Linear comparison of the three variants showed that pT-HNK130-2 and pT-HNK130-3 resulted from the sequence deletion and inversion of pT-HNK130-1. Stability tests demonstrated that pT-HNK130-1 and pT-HNK130-3 could be stably maintained in the transformants without antibiotic selection but pT-HNK130-2 was unstable. This is the first description of an IncC–IncN hybrid plasmid from an ST17 <italic>S.</italic> Indiana strain and indicates that this plasmid may further facilitate dissemination of fosfomycin and cephalosporin resistance in <italic>Salmonella.</italic></p>