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Evaluation of CTX-M steady-state mRNA, mRNA half-life and protein production in various STs of Escherichia coli.

Geyer, Chelsie N and Fowler, Randal C and Johnson, James R and Johnston, Brian and Weissman, Scott J and Hawkey, Peter and Hanson, Nancy D (2016) Evaluation of CTX-M steady-state mRNA, mRNA half-life and protein production in various STs of Escherichia coli. The Journal of antimicrobial chemotherapy, 71 (3). pp. 607-16. ISSN 1460-2091. This article is available to all HEFT staff and students via ASK HEFT Discovery tool http://tinyurl.com/z795c8c using their HEFT Athens Login.

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Official URL: https://academic.oup.com/jac/article-lookup/doi/10...

Abstract

OBJECTIVES

High levels of β-lactamase production can impact treatment with a β-lactam/β-lactamase inhibitor combination. Goals of this study were to: (i) compare the mRNA and protein levels of CTX-M-15- and CTX-M-14-producing Escherichia coli from 18 different STs and 10 different phylotypes; (ii) evaluate the mRNA half-lives and establish a role for chromosomal- and/or plasmid-encoded factors; and (iii) evaluate the zones of inhibition for piperacillin/tazobactam and ceftolozane/tazobactam.

METHODS

Disc diffusion was used to establish zone size. RNA analysis was accomplished using real-time RT-PCR and CTX-M protein levels were evaluated by immunoblotting. Clinical isolates, transformants and transconjugants were used to evaluate mRNA half-lives.

RESULTS

mRNA levels of CTX-M-15 were up to 165-fold higher compared with CTX-M-14. CTX-M-15 protein levels were 2-48-fold less than their respective transcript levels, while CTX-M-14 protein production was comparable to the observed transcript levels. Nineteen of 25 E. coli (76%) had extended CTX-M-15 mRNA half-lives of 5-15 min and 16 (100%) CTX-M-14 isolates had mRNA half-lives of <2-3 min. Transformants had mRNA half-lives of <2 min for both CTX-M-type transcripts, while transconjugant mRNA half-lives corresponded to the half-life of the donor. Ceftolozane/tazobactam zone sizes were ≥19 mm, while piperacillin/tazobactam zone sizes were ≥17 mm.

CONCLUSIONS

CTX-M-15 mRNA and protein production did not correlate. Neither E. coli ST nor phylotype influenced the variability observed for CTX-M-15 mRNA or protein produced. mRNA half-life is controlled by a plasmid-encoded factor and may influence mRNA transcript levels, but not protein levels.

Item Type: Article
Additional Information: This article is available to all HEFT staff and students via ASK HEFT Discovery tool http://tinyurl.com/z795c8c using their HEFT Athens Login.
Subjects: W Public health. Health statistics. Occupational health. Health education
WC Communicabable diseases
Divisions: Clinical Support > Infectious Diseases
Related URLs:
Depositing User: Mr Philip O'Reilly
Date Deposited: 03 Apr 2017 12:57
Last Modified: 03 Apr 2017 12:57
URI: http://www.repository.heartofengland.nhs.uk/id/eprint/1356

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