Bacteriophage Therapy to Reduce Colonization of Campylobacter jejuni in Broiler Chickens before Slaughter

Abstract

Campylobacteriosis is the most commonly reported gastrointestinal disease in humans. <i>Campybacter jejuni</i> is the main cause of the infection, and bacterial colonization in broiler chickens is widespread and difficult to prevent, leading to high risk of occurrence in broiler meat. Phage therapy represents an alternative strategy to control <i>Campylobacter</i> in poultry. The aim of this work was to assess the efficacy of two field-isolated bacteriophages against experimental infections with an anti-microbial resistant (AMR) <i>Campylobacter</i>&nbsp;<i>jejuni</i> strain. A two-step phage application was tested according to a specific combination between chickens' rearing time and specific multiplicities of infections (MOIs), in order to reduce the <i>Campylobacter</i> load in the animals at slaughtering and to limit the development of phage-resistant mutants. In particular, 75 broilers were divided into three groups (A, B and C), and phages were administered to animals of groups B and C at day 38 (Φ 16-izsam) and 39 (Φ 7-izsam) at MOI 0.1 (group B) and 1 (group C). All broilers were euthanized at day 40, and <i>Campylobacter</i>&nbsp;<i>jejuni</i> was enumerated in cecal contents. Reductions in <i>Campylobacter</i> counts were statistically significant in both group B (1 log₁₀ colony forming units (cfu)/gram (gr)) and group C (2 log₁₀ cfu/gr), compared to the control group. Our findings provide evidence about the ability of phage therapy to reduce the <i>Campylobacter</i> load in poultry before slaughtering, also associated with anti-microbial resistance pattern.