Abstract
BackgroundExtended-spectrum β-lactamases (ESBLs), particularly CTX-M- type ESBLs, are among the most important resistance determinants spreading worldwide in Enterobacteriaceae. The aim of this study was to characterize a collection of 163 ESBL-producing Escherichia coli collected in Tunisia, their ESBL-encoding plasmids and plasmid associated addiction systems.ResultsThe collection comprised 163 ESBL producers collected from two university hospitals of Sfax between 1989 and 2009. 118 isolates harbored blaCTX-M gene (101 blaCTX-M-15 gene and 17 blaCTX-M-14 gene). 49 isolates carried blaSHV-12 gene, 9 blaSHV-2a gene and only 3 blaTEM-26 gene. 16 isolates produced both CTX-M and SHV-12. The 101 CTX-M-15-producing isolates were significantly associated to phylogroup B2 and exhibiting a high number of virulence factors. 24 (23.7%) of the group B2 isolates belonged to clonal complex ST131. Pulsed-field gel electrophoresis (PFGE) typing revealed a genetic diversity of the isolates. 144 ESBL determinants were transferable mostly by conjugation. The majority of plasmid carrying blaCTX-M-15 genes (72/88) were assigned to various single replicon or multireplicon IncF types and had significantly a higher frequency of addiction systems, notably the VagCD module.ConclusionThis study demonstrates that the dissemination of CTX-M-15 producing E. coli in our setting was due to the spread of various IncF-type plasmids harboring multiple addiction systems, into related clones with high frequency of virulence determinants.
Highlights
Extended-spectrum β-lactamases (ESBLs), CTX-M- type ESBLs, are among the most important resistance determinants spreading worldwide in Enterobacteriaceae
This study demonstrates that the dissemination of CTX-M-15 producing E. coli in our setting was due to the spread of various IncF-type plasmids harboring multiple addiction systems, into related clones with high frequency of virulence determinants
Transfer of resistance and plasmid replicon type determination 144 over 179 (80%) ESBL determinants were transferable by conjugation (n = 136) or transformation (n = 8); these encoded CTX-M-15 (n = 88), CTX-M-14 (n = 15), SHV12 (n = 30), SHV-2a (n = 9) and TEM-26 (n = 2) (Table 1)
Summary
Extended-spectrum β-lactamases (ESBLs), CTX-M- type ESBLs, are among the most important resistance determinants spreading worldwide in Enterobacteriaceae. The aim of this study was to characterize a collection of 163 ESBL-producing Escherichia coli collected in Tunisia, their ESBL-encoding plasmids and plasmid associated addiction systems. Extended-spectrum β-lactamases (ESBLs) are among the most important resistance determinants spreading worldwide in Enterobacteriaceae [1,2]. CTX-M-type ESBLs have increased dramatically, and become the most prevalent ESBLs worldwide, frequently associated of this determinant in E. coli population [5]. This study was designed to characterize the ESBL-producing E. coli collected in two university hospitals of Sfax, in the southern part of Tunisia and to investigate their virulence background, their ESBL-encoding plasmids and their plasmid addiction systems
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