Untargeted metabolomics analysis of gentamicin-induced tolerant colonies of Klebsiella pneumoniae

Abstract

PurposeAntibiotic resistance development in pathogenic bacteria like Klebsiella pneumoniae seriously threatens humankind. Therefore, it is important to understand the interaction of bacteria with antibiotic agents and how it acquires resistance at the molecular level. The current study describes metabolomics analysis of K. pneumoniae sensitive strains and its gentamicin-tolerant (resistant) strains. MethodsK. pneumoniae strains were treated at five different concentrations of gentamicin, increasing from a low dose (16.2 µg/mL) to the highest dose (250 µg/mL) at three incubation time periods (24 h, 48 h, and 72 h). Colonies obtained at various concentrations and time intervals were subjected to metabolomic analysis using GC–MS. ResultsA drastic change was observed in the morphology of K. pneumoniae colonies with the increasing gentamicin concentration. Moreover, K. pneumoniae strains grown at the highest concentration (250 µg/mL) were found tolerant to 1 mg/mL gentamicin (4-folds) and considered resistant strains. A total of 459 metabolites were identified. A sequential down/up-regulation in 4, 3, and 4 metabolites were observed in association with the increasing gentamicin concentration at 24 h, 48 h, and 72 h, respectively. While with the comparative analysis of resistant and sensitive strains, a total of seven down- and sixteen up-regulated metabolites were observed. The concentration of some fatty acids and sugars have been found to increase while, a few metabolites like inosine, tyrosine, 1-propionylproline, and 2-hydroxyacetic acid have been found down-regulated in resistant samples. ConclusionThese regulator metabolites might be associated with resistance development in K. pneumoniae against gentamicin and might be helpful in the rapid detection of gentamicin-resistant clinical strains.