Transcriptomic responses of a New Delhi metallo-β-lactamase-producing Klebsiella pneumoniae isolate to the combination of polymyxin B and chloramphenicol

Synergy of the Polymyxin-Chloramphenicol Combination against New Delhi Metallo-β-Lactamase-Producing Klebsiella pneumoniae Is Predominately Driven by Chloramphenicol

“…Overall, inhibition of cellular metabolism, including energy metabolism, played a key role in the mechanism of the persistent metabolic inhibition by the combination at 24 h. This is in agreement with a previous metabolomic study of bacteriostatic antibiotic chlortetracycline that illustrated a suppression of central metabolism in Escherichia coli . Collectively, these findings together with our recent transcriptomic results demonstrate that chloramphenicol mainly drove the perturbations in the gene expression and metabolism in NDM-producing K. pneumoniae by the combination at 24 h.…”

“…Key metabolic pathways were affected by the combination as early as 1 h. For example, the level of sn -glycero-3-phosphoethanolamine was only significantly affected in the combination group, indicating the synergistic activity via perturbation of glycerophospholipid metabolism. A number of metabolites involved in cell wall biogenesis were also affected exclusively by the combination at 1 and 24 h. Our transcriptomics findings also revealed that the peptidoglycan biosynthesis pathway was enriched uniquely by the combination . Our results collectively indicate that the combination exerted significant and persistent effects on cell envelope biosynthesis in NDM-producing K. pneumoniae .…”

“…Notably, two metabolites were significantly increased: ( S )-2-acetolactate (C 5 H 8 O 4 ) and 2-hydroxy-2,4-pentadienoate (C 5 H 6 O 3 ); both metabolites were not affected by chloramphenicol monotherapy or the combination. ( S )-2-Acetolactate is involved in valine and isoleucine biosynthesis, and we found that in the transcriptomics studies of the polymyxin B and chloramphenicol combination, only polymyxin B affected this pathway . Interestingly, the degradation of 2-hydroxy-2,4-pentadienoate via mhpDFE operon leads to acetyl-CoA which can then enter the TCA cycle. , …”

“…Our recent transcriptomics results showed extensive bacterial responses to polymyxin B monotherapy (1 mg/L, continuous infusion) at 0.25 and 1 h at the gene expression level; however, metabolomic responses to the same treatment were minimal at both time points (Figure ). Notably, two metabolites were significantly increased: ( S )-2-acetolactate (C 5 H 8 O 4 ) and 2-hydroxy-2,4-pentadienoate (C 5 H 6 O 3 ); both metabolites were not affected by chloramphenicol monotherapy or the combination.…”

In silico genome-scale metabolic modeling and in vitro static time-kill studies of exogenous metabolites alone and with polymyxin B against Klebsiella pneumoniae

“…Furthermore, metabolites PHPYR, OROT, 3PG, and 3PHP have also been identified as significant metabolites perturbed by the combination ( Abdul Rahim et al, 2021 ). Although many significant metabolites were identified from the studies, the selected metabolites were those that demonstrated perturbations to both gene expression and metabolism of the same pathway [e.g., gnd and R5P in the pentose phosphate pathway (PPP); pgk and 3PG in gluconeogenesis] by the combination ( Abdul Rahim et al, 2020 ; 2021 ). For instance, transcriptomics and metabolomic results revealed that the expression of gene gnd and abundance level of R5P were downregulated and decreased in response to the polymyxin combination treatment, respectively.…”