A study comparing the healthy and diseased equine glandular gastric microbiota sampled with sheathed transendoscopic cytology brushes

The role of the equine gastrointestinal microbiota in the pathogenesis of equine glandular gastric disease (EGGD) is poorly understood. To investigate whether the glandular gastric microbiota is altered in horses with EGGD. Prospective longitudinal study. Five Thoroughbred racehorses from one training center un-derwent gastroscopy as part of poor performance investigation. Samples were taken from EGGD lesions and adjacent normal mucosa using sheathed transendoscopic cytology brushes and frozen at-80 degrees C. DNA was extracted for 16S rRNA sequencing, and sequences compared against a database to generate taxo-nomic classification of the microbiota. The same horses were sampled 6 months later. Normal glandular mucosal samples were characterized by a higher proportion of Proteobacteria (46.3%) than EGGD lesions (18.9%). Relative abundance of Firmicutes was lower in samples from normal mucosa (20.0%) than EGGD lesions (41.2%). Linear discriminant analysis effect size (LEfSe) confirmed a greater proportion of Firmi-cutes species was characteristic of samples collected from EGGD lesions due to a very high relative abun-dance of Sarcina (up to 92.4%) in two horses with EGGD. We were unable to comment on the stability of the glandular gastric microbiota over time. Small sample population. None of the horses examined had grossly normal gastric mucosa. The gastric microbiota appears altered in EGGD, although we are unable to demonstrate a causative effect. Sarcina was particularly increased in abundance in EGGD and may be a useful biomarker of disease. Sheathed cytology brushes were an effective method for sampling the gastric mucosa.Crown Copyright (c) 2022 Published by Elsevier Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Automated summary

The study found that the composition of glandular gastric microbiota in horses with EGGD has changed, with a significant increase in Sarcina, which may serve as a useful biomarker for the disease.