HP01 - 16S rRNA Amplicon Sequencing of Bile from Healthy Cats and Cats with Suspected Hepatobiliary Disease

Abstract: Background: Bacterial cholangitis is a common disease of cats yet existence of a bile microbiome in cats is unknown. This knowledge gap may limit our understanding of the pathogenesis of hepatobiliary diseases in cats.

Objectives: To establish 1) if healthy cats harbor a core microbiota in gallbladder bile and 2) any relationship between results of conventional bile culture, cytology, and 16S rRNA gene amplicon sequencing (16S sequencing).

Animals: 43 cats with suspected hepatobiliary disease and 18 control cats from a local animal control facility.

Methods: Case-control study. Bile was collected via percutaneous ultrasound-guided cholecystocentesis from cats with suspected hepatobiliary disease and post-mortem from control cats having concurrent histopathologic examination to exclude underlying disease. Bile cytology, aerobic/anaerobic culture, and 16S sequencing were performed.

Results: Both bile culture and 16S sequencing results were attained for 40 cats with suspected hepatobiliary disease and 18 controls. A positive culture was obtained from 10 cats with suspected hepatobiliary disease and 0 controls. 16S sequencing did not identify existence of a core bile microbiome. Cats with positive culture results for E. coli (n = 7) had a concurrent bloom of additional pathogenic bacteria identified by 16S sequencing. Cats that were culture-positive for non-E. coli species (n = 3) had neither the cultured bacteria nor other bacteria identified by sequencing.

Conclusions and clinical importance: Cat bile does not harbor a microbiome but may contain bacterial pathogens not identified by culture. These pathogens may contribute to pathogenesis of hepatobiliary disease, particularly in cats with bile E. coli infection.