Genomic adaptations of Campylobacter jejuni to long-term human colonisation

Abstract I5

Presenter: Samuel Bloomfield (Quadram Institute Bioscience)

Campylobacter is a genus of bacteria that has been isolated from the gastrointestinal tract of humans and animals, and the environments they inhabit around the world. Campylobacter adapt to new environments by changes in their gene content and expression, but little is known about how they adapt to long-term human colonisation. To investigate this, the genomes of 31 isolates from a New Zealand patient and 22 genomes from a United Kingdom patient that belonged to Campylobacter jejuni sequence type 45 (ST45) were compared with 209 ST45 genomes from other sources to identify the mechanisms by which Campylobacter adapts to long-term human colonisation. In addition, the New Zealand patient had their microbiome investigated using 16S rRNA metabarcoding, and their level of inflammation and immunosuppression analysed using biochemical tests. There was some evidence that long-term colonisation led to genome degradation, but more evidence that Campylobacter adapted through the accumulation of non-synonymous single nucleotide polymorphisms (SNPs) and frameshifts in genes involved in cell motility, signal transduction and the Major Outer Membrane Protein (MOMP), possibly to evade host defences. The New Zealand patient also displayed considerable variation in their microbiome, inflammation and immunosuppression over five months, and the Campylobacter collected from this patient could be divided into two subpopulations, the proportion of which correlated with the amount of gastrointestinal inflammation. This suggests that subpopulations of Campylobacter evolve within the gastrointestinal tract to adapt to changing environments. Overall, this study demonstrates how genomics, phylogenetics, 16S rRNA metabarcoding and biochemical markers can provide insight into how Campylobacter adapts to changing environments within human hosts.

About the presenter

Samuel Bloomfield is a post-doctoral research fellow that started working at the Quadram Institute in 2018 in the Mather group, researching bacteria in the food chain, epidemiology and antimicrobial resistance using genomics and metagenomics. Prior to this he completed his PhD at Massey University investigating the transmission and evolution of bacterial enteritis outbreaks.

Presenting in Speaking session 1 - Host adaptation