Pilot experiment in chickens challenged with Campylobacter jejuni CCM6191 administered enterocin M-producing probiotic strain Enterococcus faecium CCM8558 to check its protective effect

Abstract

Campylobacter jejuni is one of the most common food-borne pathogens and chickens are the main source of these bacteria. Enterococcus faecium AL41, enterocin M-producing strain (deponed to the Czech Culture Collection of Microorganisms, Brno, Czech Republic – CCM8558) is our isolate previously applied e.g. in broiler rabbits with beneficial effect. In this study it was used in a 11-day experiment with chickens (1-day-old, breed Cobb 500, n = 40) challenged with C. jejuni. Birds had free access to feed and water; they were randomly divided into four groups per 10 chicks each: control (CG), E. faecium CCM8558 (EG1), CCM8558 + C. jejuni CCM6191 (EG2), CCM6191 (EG3). E. faecium CCM8558 (10<sup>9 </sup>CFU/ml, 200 µl) in Ringer solution was administered daily per os to EG1 and EG2 for 7 days (from day 0–1). EG3 and EG2 were infected individually per os (day 4, CCM6191, 10<sup>8</sup> CFU/ml in Ringer solution, 200 µl). For microbiota evaluation, faecal mixtures (n = 5) were sampled on day 0–1 (1<sup>st</sup> sampling), on day 7 (2<sup>nd</sup> sampling), and on day 11 (3<sup>rd</sup> sampling) (day 7 of CCM8558 application, day 4 post-infection; day 4 of CCM8558 cessation, day 7 post-infection). Five birds from each group were sacrificed. CCM8558 sufficiently colonized chickens. In faeces of EG2 a tendency to reduce Campylobacter spp. (day 7 of application, day 4 of infection) was noted compared to EG2 (day 11, day 4 of cessation, day 7 post-infection; difference 1.21 log cycles), while in EG3 CCM6191 strain was not reduced. Phagocytic activity (PA) values were significantly higher in infected groups compared to CG and EG1. A significant increase in PA was also noted in EG2 and EG3 at the end of experiment compared to CG or EG1. The strain additive did not evoke oxidative stress. Biochemical parameters were influenced to the reference levels.