Resistance to piperacillin/tazobactam in Escherichia coli resulting from extensive IS26-associated gene amplification of blaTEM-1
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
BACKGROUND: bla TEM-1 encodes a narrow-spectrum β-lactamase that is inhibited by β-lactamase inhibitors and commonly present in Escherichia coli. Hyperproduction of blaTEM-1 may cause resistance to penicillin/β-lactamase inhibitor (P/BLI) combinations.
OBJECTIVES: To characterize EC78, an E. coli bloodstream isolate, resistant to P/BLI combinations, which contains extensive amplification of blaTEM-1 within the chromosome.
METHODS: EC78 was sequenced using Illumina and Oxford Nanopore Technology (ONT) methodology. Configuration of blaTEM-1 amplification was probed using PCR. Expression of blaTEM-1 mRNA was determined using quantitative PCR and β-lactamase activity was determined spectrophotometrically in a nitrocefin conversion assay. Growth rate was assessed to determine fitness and stability of the gene amplification was assessed by passage in the absence of antibiotics.
RESULTS: Illumina sequencing of EC78 identified blaTEM-1B as the only acquired β-lactamase preceded by the WT P3 promoter and present at a copy number of 182.6 with blaTEM-1B bracketed by IS26 elements. The chromosomal location of the IS26-blaTEM-1B amplification was confirmed by ONT sequencing. Hyperproduction of blaTEM-1 was confirmed by increased transcription of blaTEM-1 and β-lactamase activity and associated with a significant fitness cost; however, the array was maintained at a relatively high copy number for 150 generations. PCR screening for blaTEM amplification of isolates resistant to P/BLI combinations identified an additional strain containing an IS26-associated amplification of a blaTEM gene.
CONCLUSIONS: IS26-associated amplification of blaTEM can cause resistance to P/BLI combinations. This adaptive mechanism of resistance may be overlooked if simple methods of genotypic prediction (e.g. gene presence/absence) are used to predict antimicrobial susceptibility from sequencing data.
Originalsprog | Engelsk |
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Tidsskrift | The Journal of antimicrobial chemotherapy |
Vol/bind | 74 |
Udgave nummer | 11 |
Sider (fra-til) | 3179-3183 |
Antal sider | 5 |
ISSN | 0305-7453 |
DOI | |
Status | Udgivet - 1 nov. 2019 |
Bibliografisk note
© The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.
ID: 233654381