Unique mechanistic insights into pathways associated with the synergistic activity of polymyxin B and caspofungin against multidrug-resistant Klebsiella pneumoniae

Maytham Hussein; Labell J M Wong; Jinxin Zhao; Vanessa E Rees; Rafah Allobawi; Rajnikant Sharma; Gauri G Rao; Mark Baker; Jian Li; Tony Velkov

doi:10.1016/j.csbj.2022.02.021

Unique mechanistic insights into pathways associated with the synergistic activity of polymyxin B and caspofungin against multidrug-resistant Klebsiella pneumoniae

Comput Struct Biotechnol J. 2022 Feb 25:20:1077-1087. doi: 10.1016/j.csbj.2022.02.021. eCollection 2022.

Authors

Affiliations

¹ Department of Biochemistry and Pharmacology, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC 3010, Australia.
² Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
³ The Novo Nordisk Centre for Biosustainability, The Technical University of Denmark (DTU), 2800 Kgs. Lyngby, Denmark.
⁴ Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC, USA.
⁵ Discipline of Biological Sciences, Priority Research Centre in Reproductive Biology, Faculty of Science and IT, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.

Abstract

Klebsiella pneumoniae is an opportunistic Gram-negative pathogen causing nosocomial infections. K. pneumoniae rapidly acquires antibiotic resistance and is known as a reservoir for resistance genes. Polymyxins remain effective as a last-line therapy against infections caused by multidrug-resistant (MDR) K. pneumoniae; however, resistance to polymyxins emerges rapidly with monotherapy. Synergistic combinations of polymyxins with FDA-approved non-antibiotics are a novel approach to preserve its efficacy whilst minimising the emergence of polymyxin resistance in K. pneumoniae. This study aimed to investigate the synergistic antibacterial activity of polymyxin B in combination with the anti-fungal caspofungin against K. pneumoniae. The combination of polymyxin B and caspofungin showed marked synergistic antibacterial killing activity in checkerboard broth microdilution and static time-kill assays at clinically relevant concentrations at early (0.5 and 1 h) and later (4 h) time points. The potential bacterial killing mechanism of the combination was studied against K. pneumoniae FADDI-KP001 using metabolomics and transcriptomics studies at 0.5, 1 and 4 h. The key pathways involved in the synergistic killing action of the combination were cell wall assembly (peptidoglycan and lipopolysaccharide biosynthesis), central carbon metabolism (glycolysis, pentose phosphate pathway and tricarboxylic acid cycle) and fatty acid biosynthesis. Moreover, the combination inhibited the most common bacterial virulence pathway (phosphotransferase system) as well as the multi-resistant efflux mechanisms, including ATP-binding cassette (ABC) transporter pathway. Overall, this study sheds light on the possibility of a polymyxin-caspofungin combination for the treatment of infections caused by K. pneumoniae and may help repurpose FDA-approved caspofungin against MDR K. pneumoniae infections.

Keywords: Antifungal; Antimicrobial peptide; Caspofungin; Gram-negative; Metabolomics; Polymyxin; Transcriptomics.