IS1R-mediated plasticity of IncL/M plasmids leads to the insertion of bla OXA-48 into the Escherichia coli Chromosome.
Antimicrob Agents Chemother
; 58(7): 3785-90, 2014 Jul.
Article
em En
| MEDLINE
| ID: mdl-24752261
ABSTRACT
The OXA-48 carbapenemase is mainly encoded by â¼ 62-kb IncL/M plasmids. However, chromosome-mediated genes have been observed in Escherichia coli isolates. In this work, we investigated the genetic environment of OXA-48 in members of the family Enterobacteriaceae (n = 22) to understand how the OXA-48-encoding gene is transferred into the E. coli chromosome. The OXA-48-encoding gene was located within intact Tn1999.2 transposons in the â¼ 62-kb plasmids or within a truncated variant of Tn1999.2 for the OXA-48-encoding genes located in the chromosomes of E. coli bacteria. The analysis of the Tn1999.2 genetic environment revealed an inverted orientation of the transposon in five â¼ 62-kb plasmids (5/14 [35%]) and in all chromosome inserts (n = 8). The sequencing of pRA35 plasmid showed that this orientation of Tn1999.2 and the acquisition of an IS1R insertion sequence generated a 21.9-kb IS1R-based composite transposon encoding OXA-48 and designated Tn6237. The sequencing of a chromosomal insert encoding OXA-48 also revealed this new transposon in the E. coli chromosome. PCR mapping showed the presence of this element in all strains harboring an OXA-48-encoding chromosomal insert. However, different insertion sites of this transposon were observed in the E. coli chromosome. Overall, these findings indicate a plasticity of the OXA-48 genetic environment mediated by IS1R insertion sequences. The insertion sequences can induce the transfer of the OXA-encoding gene into E. coli chromosomes and thereby promote its persistence and expression at low levels.
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Plasmídeos
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Beta-Lactamases
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Cromossomos Bacterianos
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Proteínas de Escherichia coli
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DNA Nucleotidiltransferases
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Escherichia coli
Idioma:
En
Revista:
Antimicrob Agents Chemother
Ano de publicação:
2014
Tipo de documento:
Article