Dogs and Cats: Reservoirs for Highly Diverse Campylobacter jejuni and a Potential Source of Human Exposure

SIMPLE SUMMARY: Campylobacter is among the most common causes of bacterial gastroenteritis and is associated with post-infectious neuropathies. This organism is part of the commensal microbiota of numerous host species, including companion animals. Molecular typing approaches have been used to attribute the source of human campylobacteriosis and showed that broilers are a major infection source, while pets are a non-negligible one (10–25% of clinical cases). Since the assessment of animal colonization by Campylobacter is crucial to better understand its epidemiology, we determined the Campylobacter carriage by dogs and cats, hereafter defined as pets, and characterized genetically Campylobacter jejuni (C. jejuni) isolates. Pets appeared to frequently carry Campylobacter. The comparison of genetic profiles of C. jejuni isolates with isolates from several animal reservoirs and clinical cases revealed an overlap between profiles. These results suggest potential pets’ contamination by livestock or inversely, as well as their potential role in Campylobacter transmission to humans. However, some pets’ profiles were not isolated in livestock, which suggests the existence of other sources of pet contamination by C. jejuni or implies that pets may constitute a reservoir for Campylobacter with specific profiles. Since frequent contact occurs between pets and humans, this work emphasized the potential role of pets as a source of human exposure to Campylobacter. ABSTRACT: Assessing the carriage of Campylobacter in animal reservoirs is essential to better understand Campylobacter epidemiology. Here, we evaluated the prevalence of thermophilic Campylobacter spp. in dogs and cats, hereafter defined as pets, and characterized Campylobacter jejuni (C. jejuni) isolates to assess their genetic diversity and their potential link with isolates from other animals or human cases. During a 6-month period, 304 feces samples were collected from pets. A significantly higher prevalence of thermophilic Campylobacter spp. was found in dogs compared with cats, as well as in dogs ≤ 1-year-old compared with older dogs. C. jejuni was the predominant species found in pets, and its genomic characterization revealed a high genetic diversity. Genotypes comparison with previously characterized isolates revealed a partial overlap between C. jejuni isolates from pets, chicken, cattle, and clinical cases. This overlap suggests the potential role of livestock and humans in pets’ exposure to Campylobacter, or vice versa. The isolation of pets’ specific profiles may suggest the existence of other sources of pet contamination or imply that pets may constitute a reservoir for Campylobacter. Because of the proximity between humans and pets, along with their frequent carriage of C. jejuni, human exposure to Campylobacter from pets can be more important than previously thought.