A novel IncQ plasmid type harbouring a class 3 integron from Escherichia coli

Abstract

Objectives: To determine the genetic structures at the origin of the mobilization of the extended-spectrum β-lactamase (ESBL) blaGES-1 gene in an Escherichia coli clinical isolate. Methods: ESBL-encoding genes and class 1 or class 3 integron-specific motifs were screened. Conjugation experiments were performed to determine whether the plasmid-carrying blaGES-1 gene was self-transferable. Plasmid sequencing was achieved by a primer-walking approach. Results: The blaGES-1 gene was located in a class 3 integron. That unusual genetic structure was itself located on an ~9 kb plasmid, pQ7, which was not self-transferable. Sequence analysis revealed that plasmid pQ7 belonged to a novel subtype of the IncQ group. Conclusions: This study identified for the first time the blaGES-1 gene in E. coli and in Switzerland. It describes a novel IncQ-type plasmid subgroup that possesses original features, in particular iteron sequences that constitute a hot spot for integration of foreign DNA. © The Author 2010.