New markers for sepsis caused by Pseudomonas aeruginosa during burn infection

Introduction: Sepsis is a leading cause of mortality in burn patients. One of the major causes of sepsis in burn patients is Pseudomonas aeruginosa. We hypothesized that during dissemination from infected burn wounds and subsequent sepsis, P. aeruginosa affects the metabolome of the blood resulting in changes to specific metabolites that would serve as biomarkers for early diagnosis of sepsis caused by P. aeruginosa. Objectives: To identify specific biomarkers in the blood after sepsis caused by P. aeruginosa infection of burns. Methods: Gas chromatography with time-of-flight mass spectrometry was used to compare the serum metabolome of mice that were thermally injured and infected with P. aeruginosa (B–I) to that of mice that were neither injured nor infected, mice that were injured but not infected, and mice that were infected but not injured. Results: Serum levels of 19 metabolites were significantly increased in the B–I group compared to controls while levels of eight metabolites were significantly decreased. Thymidine, thymine, uridine, and uracil (related to pyrimidine metabolism), malate and succinate (a possible sign of imbalance in the tricarboxylic acid cycle), 5-oxoproline (related to glutamine and glutathione metabolism), and trans-4-hydroxyproline (a major component of the protein collagen) were increased. Products of amino acid metabolism were significantly decreased in the B–I group, including methionine, tyrosine, indole-3-acetate, and indole-3-propionate. Conclusion: In all, 26 metabolites were identified, including a unique combination of five metabolites (trans-4-hydroxyproline, 5-oxoproline, glycerol-3-galactoside, indole-3-acetate, and indole-3-propionate) that could serve as a set of biomarkers for early diagnosis of sepsis caused by P. aeruginosa in burn patients.