Extensive IS26 mediated gene duplication of blaTEM-1 as a cause of resistance to piperacillin-tazobactam in Escherichia coli

Lotte Jelsbak, Minna Rud Andreasen, Katrine Hartung Hansen, Martin Schou Pedersen, Kristian Schønning, Henrik Westh, Thomas arn Hansen, Michael Pedersen

Publikation: KonferencebidragKonferenceabstrakt til konferenceForskning


blaTEM-1 is a narrow spectrum beta-lactamase commonly present in Eschericia
coli and is inhibited by beta-lactamase inhibitors as tazobactam. Resistance
to piperacillin-tazobactam (PTZ) may be caused by hyperproduction
of blaTEM-1 overcoming the inhibition by tazobactam. Here we characterize
EC78, a PTZ-resistant E. coli isolate, which only contain a blaTEM-1 beta-
lactamase that is located within the chromosome.
EC78 was sequenced using both Illumina and Oxford Nanopore (ONP)
technology. Illumina sequencing identified blaTEM-1 located on a 1,905 bp
long contig preceded by a normal strength P3 promoter and bracketed by
IS26-elements. IS26-elements were only observed at one end of two long
chromosomal contigs indicating that blaTEM-1 was located within the chromosome.
We estimated the copy number of blaTEM-1 to 182.6 by comparing the average coverage of blaTEM-1 to the average coverage of the MLST alleles. ONP sequencing confirmed blaTEM-1 to be present within a region of the chromosome of EC78 poorly resolved by hybrid assembly using Illumina and ONP data; the remaining resolved chromosome consisting of 4,940,712 bp. BLAST analysis of individual ONP reads confirmed that the unresolved region contained IS26-blaTEM-1 elements organized in a head-to-tail fashion. RT-qPCR and assays for beta-lactamase production confirmed the hyperproduction of blaTEM-1. In conclusion, we show that IS26-mediated gene duplication may be a cause of blaTEM-1 hyperproduction and resistance to PTZ in E. coli. This mechanism of resistance may be easily overlooked if absence/presence of genes is used to predict antimicrobial susceptibility from sequencing data.
StatusUdgivet - 2018
BegivenhedCopenhagen Bioscience: Averting the Post-antibiotic era - Challenges and developments - Favrholm Campus, Hillerød, Danmark
Varighed: 31 okt. 20183 nov. 2018
Konferencens nummer: 15


KonferenceCopenhagen Bioscience
LokationFavrholm Campus
AndetAntibiotic resistance among bacterial pathogens is increasing posing serious health threats, and there is therefore a great need to face this challenge. The conference will bring together scientists across several research fields for discussions of possible solutions. It is clear that next generation therapeutic strategies will be rooted in creative multi-disciplinary research performed by the best scientists. Meet some of them at the forth-coming conference from 31 October to 3 November 2018.<br/><br/>Conference topics<br/><br/> Infection mechanisms, treatments and host response<br/> Antibiotic resistance<br/> Microbiomes, infections and resistance<br/> New antibiotics and treatments<br/>

Citer dette