Biology subjects

Buckner, M. M. C.

Publications and source records attributed to Buckner, M. M. C..

2 recordsLinked to original sources

bioRxiv2023

Metal complexes and conjugation: Harnessing the power of cobalt complexes to curtail plasmid transfer

BackgroundAntimicrobial resistance genes (ARG), such as extended spectrum {beta}-lactamase (ESBL) and carbapenemase genes, are commonly carried on plasmids. Plasmids can transmit between bacteria, disseminate globally, and cause clinically important resistance. Therefore, targeting plasmids could reduce ARG prevalence, and restore the efficacy of existing antibiotics. Here, we assessed the effect of four previously characterised bis(N-picolinamido)cobalt(II) complexes on the conjugative transfer of plasmids in Escherichia coli and Klebsiella pneumoniae. MethodsLiquid broth and solid agar conjugation assays were used to measure complex activity on four plasmids in E. coli. Additionally, the effect of cobalt complexes was tested on the transmission of the fluorescently tagged extended spectrum {beta}-lactamase encoding pCTgfp plasmid in E. coli and carbapenemase encoding pKpQILgfp plasmid in K. pneumoniae, using flow cytometry. ResultsAntimicrobial susceptibility testing of cobalt complexes revealed no antibacterial activity. The cobalt complexes significantly reduced conjugative transfer of RP4, R6K, and R388 plasmids on solid agar in E. coli and pKpQILgfp transmission in K. pneumoniae. None affected conjugative transfer of pKM101 or transmission of fluorescently tagged pCT in E. coli. The cobalt complexes had no effect on plasmid persistence, suggesting that they target conjugation rather than plasmid prevalence. ConclusionsTo the best of our knowledge, this is the first study to report reduced transmission of clinically relevant plasmids with cobalt complexes. These cobalt complexes are not cytotoxic towards mammalian cells and are not antibacterial, therefore they could be optimised and employed as conjugation inhibitors to reduce prevalence of AMR and/or virulence genes in animals and humans. SignificanceAntimicrobial resistance is a growing problem that poses a significant threat to modern medicine. Some of the most problematic resistance genes are carried on genetic elements, called plasmids, that can spread between bacteria. While our understanding of the mechanisms and drivers of gene transfer amongst bacteria is increasing, we lack effective tools to slow down/control these processes. Here we demonstrate for the first time that novel cobalt-based compounds have anti-plasmid activity on a subset of E. coli plasmids, and are extremely potent in K. pneumoniae carrying a clinical carbapenem-resistance plasmid, without impacting plasmid maintenance. This finding forms the foundations of a potential strategy to control the transfer of genes within Gram-negative bacteria, which has implications for AMR and virulence.

microbiology↗

bioRxiv2023

Growth in a biofilm promotes conjugation of a blaNDM-1-bearing plasmid between Klebsiella pneumoniae strains

Antimicrobial resistance (AMR) is a growing problem, especially in Gram-negative Enterobacteriaceae such as Klebsiella pneumoniae. Horizontal transfer of conjugative plasmids contributes to AMR gene dissemination. Bacteria such as K. pneumoniae commonly exist in biofilms, yet most studies focus on planktonic cultures. Here we studied the transfer of a multidrug resistance plasmid in planktonic and biofilm populations of K. pneumoniae. We determined plasmid transfer from a clinical isolate, CPE16, which carried four plasmids, including the 119-kbp blaNDM-1-bearing F-type plasmid pCPE16_3, in planktonic and biofilm conditions. We found that transfer frequency of pCPE16_3 in a biofilm was orders-of-magnitude higher than between planktonic cells. In 5/7 sequenced transconjugants multiple plasmids had transferred. Plasmid acquisition had no detectable growth impact on transconjugants. Gene expression of the recipient and a transconjugant was investigated by RNA-sequencing in three lifestyles: planktonic exponential growth, planktonic stationary phase, and biofilm. We found that lifestyle had a substantial impact on chromosomal gene expression, and plasmid carriage affected chromosomal gene expression most in stationary planktonic and biofilm lifestyles. Furthermore, expression of plasmid genes was lifestyle-dependent, with unique signatures across the three conditions. Our study shows that growth in biofilm greatly increased the risk of conjugative transfer of a carbapenem resistance plasmid in K. pneumoniae without fitness costs and minimal transcriptional rearrangements, thus highlighting the importance of biofilms in the spread of AMR in this opportunistic pathogen. ImportanceCarbapenem-resistant K. pneumoniae is particularly problematic in hospital settings. Carbapenem resistance genes can transfer between bacteria via plasmid conjugation. Alongside drug resistance, K. pneumoniae can form biofilms on hospital surfaces, at infection sites and on implanted devices. Biofilms are naturally protected and can be inherently more tolerant to antimicrobials than their free-floating counterparts. There have been indications that plasmid transfer may be more likely in biofilm populations, thus creating a conjugation hotspot. However, there is no clear consensus on the effect of the biofilm lifestyle on plasmid transfer. Therefore, we aimed to explore the relationship between plasmid transfer and biofilms, and the impact of plasmid acquisition on the host bacterial cell. Our data show resistance plasmid transfer is greatly increased in a biofilm versus planktonic growth, which may be a significant contributing factor to the rapid dissemination of resistance plasmids in K. pneumoniae.

microbiology↗