The Influence of Iron and Lignin on Molecules of the Gastrointestinal Microbiome and Its Effect on the Conjugation of Carbapenem Resistance Plasmids

Abstract

The gastrointestinal microbiome has acted a reservoir for antibiotic resistance genes by harbouring favourable conditions for the the conjugative transfer of resistance plasmids. Resistance against carbapenems, the last resort β-lactam antibiotics, has been on the rise and is mainly mediated by the spread of carbapenemase-encoding plasmids by Klebsiella pneumoniae. Dietary intake of iron and iron chelators can modulate the metabolic and microbial profile of the gastrointestinal microbiome. This project focused on investigating the influence that molecules produced by the gastrointestinal microbiome might have on the conjugation of carbapenem resistance plasmids in K. pneumoniae in reaction to iron and lignin supplementation. A fluorescence reporter system was used to determine the effect of iron and lignin co-supplementation to an ex-vivo colonic supernatant on the conjugation of an endemic carbapenemase-encoding plasmid called pKp-QIL. This was followed by plating-based conjugation assays which measured the frequency of conjugation of a plasmid from clinical isolate called pCPE16_3 in an iron and lignin co-supplemented ex-vivo colonic supernatant. This project has revealed that lignin has no effect on the conjugation of resistance plasmids in iron- available gastrointestinal microbiome.