Molecular-based detection of the gastrointestinal pathogen Campylobacter ureolyticus in unpasteurized milk samples from two cattle farms in Ireland

Human campylobacterosis is generally regarded as a zoonosis with numerous reservoirs in the natural environment [1]. While Campylobacter spp. rarely cause disease in livestock, foodstuffs originating from such animals appear to be the most common source of infection for humans.Despite the fact that there are 25 species belonging to the Campylobacter genus [2], the primary focus of the food safety and protection agencies to date, in conjunction with clinical laboratories, has been the detection of thermophilic Campylobacter species associated with human diseases [3,4]. However, advances in molecular detection systems continue to highlight the fact that routine Campylobacter culture methods, employed by the majority of clinical laboratories, are incapable of detecting the fastidious and non-thermophilic Campylobacter spp [5]. Recent work in our laboratory has focused on the identification and characterisation of these atypical species of potential clinical importance [3,6]. Although failing to grow in routine culture, species specific PCR following a multiplex PCR based detection system (EntericBio, Serosep Ltd. Limerick, Ireland) identified C. ureolyticus in 23.8% of 349 previously genus-positive samples [6], making C. ureolyticus the second most common Campylobacter species (after C. jejuni) detected in faecal samples of patients presenting with gastroenteritis in Southern Ireland. Moreover, this species has also been detected and isolated from a number of patients presenting with Crohn's disease [7] and Ulcerative Colitis [8]; raising further questions as to its potential role as a significant human pathogen. Importantly, C. ureolyticus has been shown to be capable of attaching and translocating through the intestinal epithelia, inducing cellular damage and microvillus degradation [9].The source of C. ureolyticus has, until now, remained unknown. Herein, we report for the first time the presence of this bacterium in cow’s milk, which goes some way to answering the