Colonisation of a Phage Susceptible <i>Campylobacter jejuni</i> Population in Two Phage Positive Broiler Flocks

<div><p>The pathogens <i>Campylobacter jejuni</i> and <i>Campylobacter coli</i> are commensals in the poultry intestine and campylobacteriosis is one of the most frequent foodborne diseases in developed and developing countries. Phages were identified to be effective in reducing intestinal <i>Campylobacter</i> load and this was evaluated, in the first field trials which were recently carried out. The aim of this study was to further investigate <i>Campylobacter</i> population dynamics during phage application on a commercial broiler farm. This study determines the superiority in colonisation of a <i>Campylobacter</i> type found in a field trial that was susceptible to phages in <i>in vitro</i> tests. The colonisation factors, i.e. motility and gamma glutamyl transferase activity, were increased in this type. The clustering in phylogenetic comparisons of MALDI-TOF spectra did not match the ST, biochemical phenotype and phage susceptibility. Occurrence of <i>Campylobacter jejuni</i> strains and phage susceptibility types with different colonisation potential seem to play a very important role in the success of phage therapy in commercial broiler houses. Thus, mechanisms of both, phage susceptibility and <i>Campylobacter</i> colonisation should be further investigated and considered when composing phage cocktails.</p>