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Antimicrob Agents Chemother. 2017 Apr 24;61(5). pii: e00014-17. doi: 10.1128/AAC.00014-17. Print 2017 May.

Structural Alteration of OmpR as a Source of Ertapenem Resistance in a CTX-M-15-Producing Escherichia coli O25b:H4 Sequence Type 131 Clinical Isolate.

Author information

1
Département d'Anesthésie-Réanimation, CHU Amiens-Picardie, and INSERM U1088, Université de Picardie Jules Verne, Amiens, France.
2
INSERM, IAME, UMR 1137, Paris, France.
3
Université de Paris Diderot, IAME, UMR 1137, Sorbonne Paris Cité, Paris, France.
4
UMR 8030, CNRS, Université Évry-Val-d'Essonne, CEA, Institut de Génomique-Genoscope, Laboratoire d'Analyses Bioinformatiques pour la Génomique et le Métabolisme and Laboratoire d'Informatique Scientifique, Évry, France.
5
Institut de Biologie de l'Ecole Normale Supérieure, ENS, CNRS UMR8197, INSERM U1024, Paris, France.
6
APHP, Hôpital Bichat Claude Bernard, Laboratoire de Génétique Moléculaire, Paris, France.
7
INSERM, IAME, UMR 1137, Paris, France hedi.mammeri@wanadoo.fr.
8
APHP, Hôpital Bichat Claude Bernard, Laboratoire de Bactériologie, Paris, France.

Abstract

In this study, an ertapenem-nonsusceptible Escherichia coli isolate was investigated to determine the genetic basis for its carbapenem resistance phenotype. This clinical strain was recovered from a patient that received, 1 year previously, ertapenem to treat a cholangitis due to a carbapenem-susceptible extended-spectrum-β-lactamase (ESBL)-producing E. coli isolate. Whole-genome sequencing of these strains was performed using Illumina and single-molecule real-time sequencing technologies. It revealed that they belonged to the ST131 clonal group, had the predicted O25b:H4 serotype, and produced the CTX-M-15 and TEM-1 β-lactamases. One nucleotide substitution was identified between these strains. It affected the ompR gene, which codes for a regulatory protein involved in the control of OmpC/OmpF porin expression, creating a Gly-63-Val substitution. The role of OmpR alteration was confirmed by a complementation experiment that fully restored the susceptibility to ertapenem of the clinical isolate. A modeling study showed that the Gly-63-Val change displaced the histidine-kinase phosphorylation site. SDS-PAGE analysis revealed that the ertapenem-nonsusceptible E. coli strain had a decreased expression of OmpC/OmpF porins. No significant defect in the growth rate or in the resistance to Dictyostelium discoideum amoeba phagocytosis was found in the ertapenem-nonsusceptible E. coli isolate compared to its susceptible parental strain. Our report demonstrates for the first time that ertapenem resistance may emerge clinically from ESBL-producing E. coli due to mutations that modulate the OmpR activity.

KEYWORDS:

ESBL; OmpR; ST131; avibactam; carbapenem; envZ; temocillin

PMID:
28264855
PMCID:
PMC5404536
DOI:
10.1128/AAC.00014-17
[Indexed for MEDLINE]
Free PMC Article

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