How new treatment options such as microbiome restoration therapies can help dogs and cats with E. coli flare-ups.

Escherichia coli. It’s one of the most well-studied bacteria in the world that can be found in the digestive tracts of most animals. While most E. coli strains are harmless, some are pathogenic¹, some are opportunistic pathogens², and some provide a probiotic effect³.

You’ve likely seen an E. coli flare-up in one of your patients. But what does it mean for the health of their gut microbiome? Here we cover how E. coli relates to cat and dog gut health and discuss new research on novel solutions for symptomatic patients.

Causes of high E. coli counts

Other than a direct E. coli infection, there are other mechanisms that can trigger the overgrowth of intestinal E. coli.

Mucosal inflammation

Elevated E. coli levels can result from increased mucus production, a common inflammatory host response. Mucosal inflammation introduces metabolites, such as nitrate, that allow bacteria in the family Enterobacteriaceae, including E. coli to flourish⁴. Because increased E. coli levels can trigger inflammation, they can be self-perpetuating.

Microbial diversity imbalances

Microbiome diversity imbalances can also contribute to high E. coli levels. One study on domestic cats and dogs reported that measures of bacterial diversity, evenness, and richness were lower in cats and dogs with elevated E. coli levels compared to healthy controls⁵. Interestingly, similar findings have been reported in animals with recent antibiotic exposure⁶.

Treatment options

Inflammation mitigation

For patients with high E. coli due to increased mucosal gut inflammation, an effective long-term solution is to treat for inflammation. This indirectly targets E. coli and other pathogenic bacteria that flourish in a self-perpetuating inflamed environment. However, using medications like nonsteroidal anti-inflammatory drugs to reduce inflammation affects the composition and function of the gut microbiome and host physiology, resulting in dysbiosis.

Fortunately, two alternative and complementary approaches are effective in combating both chronic inflammation and elevated E. coli levels, while supporting microbiome health: FMTs and bacteriophage therapy.

Fecal Microbiota Transplants (FMTs)

Fecal microbiota transplants (FMTs) involve the transfer of fecal matter – inclusive of a complete microbial ecosystem, primary and secondary bile acids, short chain fatty acids, and other host factors – from a host-specific healthy donor to a recipient. The procedure can be administered in several ways, with oral capsules offering a less invasive and more affordable alternative to delivery via enema.

FMTs are appropriate for patients with a microbiome imbalance. They can also be used to treat gut inflammation and improve clinical signs, such as diarrhea and vomiting.

Learn more about microbiome restoration therapies here.

Bacteriophage therapy

New bacteriophage therapies offer a targeted approach for patients with high E. coli levels. While antibiotics have historically been used by veterinarians to treat E. coli infections, they can wipe out beneficial anaerobes, spread antibiotic resistance, and even cause an increase in E. coli levels. Unlike antibiotics, bacteriophage therapies selectively target specific bacteria and do not harm non-pathogenic strains. Recently, researchers at Colorado State University found that bacteriophage therapy effectively treats high E. coli⁷.

Learn more about the role of E. coli in chronic enteropathy cases here.

1. Croxen, M. A. et al. Recent advances in understanding enteric pathogenic Escherichia coli. Clin. Microbiol. Rev. 26, 822–880 (2013).
2. Kaper, J. B., Nataro, J. P. & Mobley, H. L. Pathogenic Escherichia coli. Nat. Rev. Microbiol. 2, 123–140 (2004).
3. Ukena, S. N. et al. Probiotic Escherichia coli Nissle 1917 inhibits leaky gut by enhancing mucosal integrity. PLoS One 2, e1308 (2007).
4. Winter, S. E. et al. Host-Derived Nitrate Boosts Growth of E. coli in the Inflamed Gut. Science 339, 708–711 (2013).
5. 2020 ACVIM Forum On Demand Research Abstract Program. J. Vet. Intern. Med. Abstract GI15, (2020).
6. Mansfield, C. S. et al. Remission of histiocytic ulcerative colitis in Boxer dogs correlates with eradication of invasive intramucosal Escherichia coli. J. Vet. Intern. Med. 23, 964–969 (2009).
7. Febvre, H. P. et al. PHAGE Study: Effects of Supplemental Bacteriophage Intake on Inflammation and Gut Microbiota in Healthy Adults. Nutrients 11, (2019).