Keynote Message

The intestinal tract is lined by a single layer of epithelial cells that is responsible for digestion and absorption of all of the nutrients and water that sustain life, while at the same time preventing the translocation of bacteria, antigens, and ingested toxins into the body. The last several years have seen great advances in our understanding of the intestinal microbiome and particularly the role of the mucosa-associated bacteria in host defense. With the advent of fluorescence in situ hybridization, individual bacteria can now be visually localized and identified to the genus, and sometimes species level. Increasing use of molecular diagnostics has made detection of diarrheal pathogens much easier but has also revealed that many of these infectious agents can also be observed in animals and people without clinical signs of disease. Host- and pathogen-specific factors that are responsible for why some patients are susceptible to disease while others remain asymptomatic has become an important focus toward a better understanding of the nuances of disease pathogenesis. In this session, we will discuss several minimally invasive diarrheal pathogens of dogs and cats and what is currently understood about their pathogenic effects and host strategies to combat them. A particular emphasis will be given to recent research findings identifying an association between enteropathogenic E. coli infection and diarrhea-related mortality in kittens and the impact of commensal bacteria in mediating colonization resistance.

Key References

1.  Ghosh A, Borst L, Stauffer SH, Suyemoto M, Moisan P, Zurek L, Gookin JL. Mortality in kittens is associated with a shift in ileum mucosa-associated enterococci from Enterococcus hirae to biofilm-forming Enterococcus faecalis and adherent Escherichia coli. J Clin Microbiol. 2013;51:3567–3578. DOI: doi: 10.1128/JCM.00481-13.

2.  Foster DM, Stauffer SH, Stone MC, Gookin JL. Proteasome inhibition of pathologic shedding of enterocytes to defend barrier function requires X-linked inhibitor of apoptosis protein and nuclear factor-κB. Gastroenterology. 2012;143:133–144. DOI: 10.1053/j.gastro.2012.03.030.

3.  Nicklas JL, Moisan P, Stone MR, Gookin JL. In situ molecular diagnosis and histopathological characterization of enteroadherent Enterococcus hirae infection in pre-weaning-age kittens. J Clin Microbiol. 2010;48:2814–2820. DOI: 10.1128/JCM.00916-09.

4.  Tolbert MK, Stauffer SH, Brand MD, Gookin JL. Cysteine protease activity of feline Tritrichomonas foetus promotes adhesion-dependent cytotoxicity to intestinal epithelial cells. Infect Immun. 2014;82:2851–2859. DOI: 10.1128/IAI.01671-14.