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Co-occurrence of mcr-1 in the chromosome and on an IncHI2 plasmid: persistence of colistin resistance in Escherichia coli.
- Source :
-
International Journal of Antimicrobial Agents . Jun2018, Vol. 51 Issue 6, p842-847. 6p. - Publication Year :
- 2018
-
Abstract
- Two colistin-resistant Escherichia coli strains (FS13Z2S and FS3Z6C) possessing chromosomally encoded mcr-1 isolated from swine were characterised. Whole-genome sequencing revealed that in strain FS13Z2S mcr-1 occurred in triplicate in the chromosome with another copy encoded on a pHNSHP45-2-like IncHI2 plasmid, whereas in strain FS3Z6C only one copy mcr-1 was inserted in the chromosome. It seems likely that the triplication of chromosomal copies of mcr-1 in FS13Z2S is due to intramolecular transposition events via a composite transposon containing an mcr-1 cassette bracketed by two copies of insertion sequence IS Apl1 , and the pap2 gene at the insertion site was truncated by an IS 1294 -like element. In plasmid pFS13Z2S and the chromosome of strain FS3Z6C, only a single copy of IS Apl1 was present upstream of the mcr-1 cassette. The two strains exhibited similar colistin minimum inhibitory concentrations (MICs) and featured phosphoethanolamine addition to lipid A, without regard to the copy number of mcr-1 . The mcr-1 -harbouring plasmid was unstable in wild-type strain FS13Z2S and was quickly lost after 7 days of passage on colistin-free Luria–Bertani broth containing 0.5% SDS, but the mcr-1 copies on the chromosome persisted. These results reveal that the single copy of mcr-1 could result in modification of lipopolysaccharide (LPS) and cause colistin resistance in E. coli . Acquisition of multiple copies of mcr-1 , especially on the chromosome, would facilitate stable persistence of colistin resistance in the host strain. [ABSTRACT FROM AUTHOR]
- Subjects :
- *COLISTIN
*ESCHERICHIA coli
*PLOIDY
*LIPOPOLYSACCHARIDES
*PLASMIDS
*THERAPEUTICS
Subjects
Details
- Language :
- English
- ISSN :
- 09248579
- Volume :
- 51
- Issue :
- 6
- Database :
- Academic Search Index
- Journal :
- International Journal of Antimicrobial Agents
- Publication Type :
- Academic Journal
- Accession number :
- 129922369
- Full Text :
- https://doi.org/10.1016/j.ijantimicag.2018.01.007