Amalia Bogri, PhD student, presented her work studying antimicrobial resistance in the gut microbiome of cockroaches. She is sharing her abstract and poster from the Symposium for Bacterial Genomics and Ecology (bageco2023.org).
Transmission of antimicrobial resistance in the gut microbiome of sub-social insects
Aim:
The rapid increase of antimicrobial resistance (AMR) poses a major threat to global health. The emergence and dissemination of AMR through the commensal microbiome aggravates the problem due to the potential horizontal gene transfer of AMR genes to pathogens. Several mathematical models explore the effect of AMR transmission by commensal bacteria; yet, experimental studies on between-host transmission are rare and challenging to set up.
In this study we examine a sub-social gregarious species of cockroach (Pycnoscelus surinamensis) as a possible animal model for AMR transmission experiments. The first objective is to demonstrate that the effect of antimicrobial treatment in the gut microbiome of a treated population is detectable with metagenomic sequencing. The second objective is to determine whether AMR genes can be spread and established in untreated individuals after contact with treated ones.
Methods:
For the first objective, one cockroach population was split into two, with one group being treated with tetracycline daily for eight days. For the second objective, the two populations were then colour-marked and mixed for eight more days. Gut samples in triplicates were taken from all groups throughout the experiment. DNA was extracted with the QIAamp Microbiome Kit, to deplete host DNA, and then shotgun sequenced with Illumina, NovaSeq platform. The raw reads were trimmed and then mapped with KMA against the ResFinder database for AMR genes and a genomic database for taxonomic identification. The metagenomic count datasets were used to estimate α-diversity and β-diversity at different levels, the latter with compositional methods for ordination and differential abundance.
Results:
Our results show that antimicrobial treatment disrupted the gut microbiome of the treated hosts, reducing the evenness of the bacterial community and increasing the relative abundance of tetracycline AMR genes. In the second part of the experiment, the relative abundance of tetracycline AMR genes was higher in the untreated hosts that interacted with treated individuals compared to the untreated control. Additionally, the treated hosts that interacted with untreated ones exhibited recovery of their bacterial diversity compared to the treated controls.
Conclusions:
Metagenomic analysis of the cockroach gut microbiome was able to capture shifts in the AMR gene profile and bacterial community composition due to antimicrobial treatment, as well as changes due to bacterial transmission between individuals. Gregarious cockroaches are thus a good candidate for experiments on the transmission of AMR and can be used to validate other theoretical transmission models.
Amalia Bogri's poster