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Metabolomics Study of the Synergistic Killing of Polymyxin B in Combination with Amikacin against Polymyxin-Susceptible and -Resistant Pseudomonas aeruginosa.

ABSTRACT: In the present study, we employed untargeted metabolomics to investigate the synergistic killing mechanism of polymyxin B in combination with an aminoglycoside, amikacin, against a polymyxin-susceptible isolate of Pseudomonas aeruginosa, FADDI-PA111 (MIC = 2 mg/liter for both polymyxin B and amikacin), and a polymyxin-resistant Liverpool epidemic strain (LES), LESB58 (the corresponding MIC for both polymyxin B and amikacin is 16 mg/liter). The metabolites were extracted 15 min, 1 h, and 4 h following treatment with polymyxin B alone (2 mg/liter for FADDI-PA111; 4 mg/liter for LESB58), amikacin alone (2 mg/liter), and both in combination and analyzed using liquid chromatography-mass spectrometry (LC-MS). At 15 min and 1 h, polymyxin B alone induced significant perturbations in glycerophospholipid and fatty acid metabolism pathways in FADDI-PA111 and, to a lesser extent, in LESB58. Amikacin alone at 1 and 4 h induced significant perturbations in peptide and amino acid metabolism, which is in line with the mode of action of aminoglycosides. Pathway analysis of FADDI-PA111 revealed that the synergistic effect of the combination was largely due to the inhibition of cell envelope biogenesis, which was driven initially by polymyxin B via suppression of key metabolites involved in lipopolysaccharide, peptidoglycan, and membrane lipids (15 min and 1 h) and later by amikacin (4 h). Overall, these novel findings demonstrate that the disruption of cell envelope biogenesis and central carbohydrate metabolism, decreased levels of amino sugars, and a downregulated nucleotide pool are the metabolic pathways associated with the synergistic killing of the polymyxin-amikacin combination against P. aeruginosa This mechanistic study might help optimize synergistic polymyxin B combinations in the clinical setting.

SUBMITTER: Hussein M

PROVIDER: S-EPMC7187587 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Metabolomics Study of the Synergistic Killing of Polymyxin B in Combination with Amikacin against Polymyxin-Susceptible and -Resistant Pseudomonas aeruginosa.

Hussein Maytham M Han Mei-Ling ML Zhu Yan Y Zhou Qi Q Lin Yu-Wei YW Hancock Robert E W REW Hoyer Daniel D Creek Darren J DJ Li Jian J Velkov Tony T

Antimicrobial agents and chemotherapy 20191220 1

In the present study, we employed untargeted metabolomics to investigate the synergistic killing mechanism of polymyxin B in combination with an aminoglycoside, amikacin, against a polymyxin-susceptible isolate of <i>Pseudomonas aeruginosa</i>, FADDI-PA111 (MIC = 2 mg/liter for both polymyxin B and amikacin), and a polymyxin-resistant Liverpool epidemic strain (LES), LESB58 (the corresponding MIC for both polymyxin B and amikacin is 16 mg/liter). The metabolites were extracted 15 min, 1 h, and 4 ...[more]

PMID: 31611351

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Project description:Polymyxins are currently used as the last-resort antibiotics against multidrug-resistant Acinetobacter baumannii. As resistance to polymyxins emerges in A. baumannii with monotherapy, combination therapy is often the only remaining treatment option. A novel approach is to employ the combination of polymyxin B with non-antibiotic drugs. In the present study, we employed metabolomics to investigate the synergistic mechanism of polymyxin B in combination with the antineoplastic drug mitotane against polymyxin-susceptible and -resistant A. baumannii. The metabolomes of four A. baumannii strains were analyzed following treatment with polymyxin B, mitotane and the combination. Polymyxin B monotherapy induced significant perturbation in glycerophospholipid (GPL) metabolism and histidine degradation pathways in polymyxin-susceptible strains, and minimal perturbation in polymyxin-resistant strains. Mitotane monotherapy induced minimal perturbation in the polymyxin-susceptible strains, but caused significant perturbation in GPL metabolism, pentose phosphate pathway and histidine degradation in the LPS-deficient polymyxin-resistant strain (FADDI-AB065). The polymyxin B - mitotane combination induced significant perturbation in all strains except the lipid A modified polymyxin-resistant FADDI-AB225 strain. For the polymyxin-susceptible strains, the combination therapy significantly perturbed GPL metabolism, pentose phosphate pathway, citric acid cycle, pyrimidine ribonucleotide biogenesis, guanine ribonucleotide biogenesis, and histidine degradation. Against FADDI-AB065, the combination significantly perturbed GPL metabolism, pentose phosphate pathway, citric acid cycle, and pyrimidine ribonucleotide biogenesis. Overall, these novel findings demonstrate that the disruption of the citric acid cycle and inhibition of nucleotide biogenesis are the key metabolic features associated with synergistic bacterial killing by the combination against polymyxin-susceptible and -resistant A. baumannii.

Project description:Polymyxins are a last-line therapy against multidrug-resistant Pseudomonas aeruginosa; however, resistance to polymyxins has been increasingly reported. Therefore, understanding the mechanisms of polymyxin activity and resistance is crucial for preserving their clinical usefulness. This study employed comparative metabolomics and transcriptomics to investigate the responses of polymyxin-susceptible P. aeruginosa PAK (polymyxin B MIC, 1 mg/liter) and its polymyxin-resistant pmrB mutant PAKpmrB6 (MIC, 16 mg/liter) to polymyxin B (4, 8, and 128 mg/liter) at 1, 4, and 24 h, respectively. Our results revealed that polymyxin B at 4 mg/liter induced different metabolic and transcriptomic responses between polymyxin-susceptible and -resistant P. aeruginosa. In strain PAK, polymyxin B significantly activated PmrAB and the mediated arn operon, leading to increased 4-amino-4-deoxy-L-arabinose (L-Ara4N) synthesis and the addition to lipid A. In contrast, polymyxin B did not increase lipid A modification in strain PAKpmrB6. Moreover, the syntheses of lipopolysaccharide and peptidoglycan were significantly decreased in strain PAK but increased in strain PAKpmrB6 due to polymyxin B treatment. In addition, 4 mg/liter polymyxin B significantly perturbed phospholipid and fatty acid levels and induced oxidative stress in strain PAK, but not in PAKpmrB6. Notably, the increased trehalose-6-phosphate levels indicate that polymyxin B potentially caused osmotic imbalance in both strains. Furthermore, 8 and 128 mg/liter polymyxin B significantly elevated lipoamino acid levels and decreased phospholipid levels but without dramatic changes in lipid A modification in wild-type and mutant strains, respectively. Overall, this systems study is the first to elucidate the complex and dynamic interactions of multiple cellular pathways associated with the polymyxin mode of action against P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa has been highlighted by the recent WHO Global Priority Pathogen List due to multidrug resistance. Without new antibiotics, polymyxins remain a last-line therapeutic option for this difficult-to-treat pathogen. The emergence of polymyxin resistance highlights the growing threat to our already very limited antibiotic armamentarium and the urgency to understand the exact mechanisms of polymyxin activity and resistance. Integration of the correlative metabolomics and transcriptomics results in the present study discovered that polymyxin treatment caused significant perturbations in the biosynthesis of lipids, lipopolysaccharide, and peptidoglycan, central carbon metabolism, and oxidative stress. Importantly, lipid A modifications were surprisingly rapid in response to polymyxin treatment at clinically relevant concentrations. This is the first study to reveal the dynamics of polymyxin-induced cellular responses at the systems level, which highlights that combination therapy should be considered to minimize resistance to the last-line polymyxins. The results also provide much-needed mechanistic information which potentially benefits the discovery of new-generation polymyxins.

Dataset Information

Metabolomics Study of the Synergistic Killing of Polymyxin B in Combination with Amikacin against Polymyxin-Susceptible and -Resistant Pseudomonas aeruginosa.

Publications

Metabolomics Study of the Synergistic Killing of Polymyxin B in Combination with Amikacin against Polymyxin-Susceptible and -Resistant Pseudomonas aeruginosa.

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