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pH plays a role in the mode of action of trimethoprim on Escherichia coli

AlRabiah, H, Allwood, JW, Correa, E, Xu, Y and Goodacre, R (2018) pH plays a role in the mode of action of trimethoprim on Escherichia coli. PLOS ONE, 13 (7).

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Abstract

Metabolomics-based approaches were applied to understand interactions of trimethoprim with Escherichia coli K-12 at sub-minimum inhibitory concentrations (MIC≈0.2, 0.03 and 0.003 mg L-1). Trimethoprim inhibits dihydrofolate reductase and thereby is an indirect inhibitor of nucleic acid synthesis. Due to the basicity of trimethoprim, two pH levels (5 and 7) were selected which mimicked healthy urine pH. This also allowed investigation of the effect on bacterial metabolism when trimethoprim exists in different ionization states. UHPLC-MS was employed to detect trimethoprim molecules inside the bacterial cell and this showed that at pH 7 more of the drug was recovered compared to pH 5; this correlated with classical growth curve measurements. FT-IR spectroscopy was used to establish recovery of reproducible phenotypes under all 8 conditions (3 drug levels and control in 2 pH levels) and GC-MS was used to generate global metabolic profiles. In addition to finding direct mode-of-action effects where nucleotides were decreased at pH 7 with increasing trimethoprim levels, off-target pH-related effects were observed for many amino acids. Additionally, stress-related effects were observed where the osmoprotectant trehalose was higher at increased antibiotic levels at pH 7. This correlated with glucose and fructose consumption and increase in pyruvate-related products as well as lactate and alanine. Alanine is a known regulator of sugar metabolism and this increase may be to enhance sugar consumption and thus trehalose production. These results provide a wider view of the action of trimethoprim. Metabolomics indicated alternative metabolism areas to be investigated to further understand the off-target effects of trimethoprim.

Item Type: Article
Uncontrolled Keywords: Science & Technology; Multidisciplinary Sciences; Science & Technology - Other Topics; MINIMUM REPORTING STANDARDS; URINARY-TRACT-INFECTIONS; GAS-CHROMATOGRAPHY; MASS-SPECTROMETRY; HOMEOSTASIS; PATHOGENS; SERUM; BIOSYNTHESIS; SPECTROSCOPY; METABOLOMICS; Science & Technology; Multidisciplinary Sciences; Science & Technology - Other Topics; MINIMUM REPORTING STANDARDS; URINARY-TRACT-INFECTIONS; GAS-CHROMATOGRAPHY; MASS-SPECTROMETRY; HOMEOSTASIS; PATHOGENS; SERUM; BIOSYNTHESIS; SPECTROSCOPY; METABOLOMICS; Escherichia coli K12; Trimethoprim; Anti-Bacterial Agents; Chromatography, Liquid; Microbial Sensitivity Tests; Dose-Response Relationship, Drug; Hydrogen-Ion Concentration; Mass Spectrometry; Anti-Bacterial Agents; Chromatography, Liquid; Dose-Response Relationship, Drug; Escherichia coli K12; Hydrogen-Ion Concentration; Mass Spectrometry; Microbial Sensitivity Tests; Trimethoprim; General Science & Technology
Subjects: R Medicine > R Medicine (General)
Divisions: Computer Science and Mathematics
Publisher: Public Library of Science
SWORD Depositor: A Symplectic
Date Deposited: 15 Nov 2024 16:50
Last Modified: 15 Nov 2024 17:00
DOI or ID number: 10.1371/journal.pone.0200272
Editors: Rodrigues-Lima, F
URI: https://researchonline.ljmu.ac.uk/id/eprint/24793
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