Reduction of Campylobacter jejuni in Broiler Chicken by Successive Application of Group II and Group III Phages

Background Bacteriophage treatment is a promising tool to reduce Campylobacter in chickens. Several studies have been published where group II or group III phages were successfully applied. However, these two groups of phages are different regarding their host ranges and host cell receptors. Therefore, a concerted activity of group II and group III phages might enhance the efficacy of a treatment and decrease the number of resistant bacteria. Results In this study we have compared the lytic properties of some group II and group III phages and analysed the suitability of various phages for a reduction of C. jejuni in broiler chickens. We show that group II and group III phages exhibit different kinetics of infection. Two group III and one group II phage were selected for animal experiments and administered in different combinations to three groups of chickens, each containing ten birds. While group III phage CP14 alone reduced Campylobacter counts by more than 1 log10 unit, the concomitant administration of a second group III phage (CP81) did not yield any reduction, probably due to the development of resistance induced by this phage. One group of chickens received phage CP14 and, 24 hours later, group II phage CP68. In this group of animals, Campylobacter counts were reduced by more than 3 log10 units. Conclusion The experiments illustrated that Campylobacter phage cocktails have to be carefully composed to achieve the best results

Reduction of <i>C. jejuni</i> 3871 by group III phages in vitro.

<p>Each experiment was performed in triplicate. For better clarity, only mean values without standard deviations are shown.</p

<i>Campylobacter</i> strains and phages used in this study.

<p>NCTC; National Collection of Type Cultures, Health Protection Agency, UK.</p><p><i>Campylobacter</i> strains and phages used in this study.</p

pH and temperature stability of the phages CP14, CP81 and CP68.

<p>Each experiment was performed in triplicate. Bars indicate standard deviations. pH stability was tested at 20°C. As indicator strain for phage activity (quantified as PFU/ml), <i>C. jejuni</i> 3871 was used. Arrows indicate the initial phage titers.</p

Design and outcome of the animal experiment.

<p>A. Time scale of the experiment. B. Reduction of <i>C. jejuni</i> in the chickens. Mean values of <i>Campylobacter</i> counts (CFU/g feces) and standard deviations are shown.</p

Reduction of <i>C. jejuni</i> 3871 in vitro by simultaneous and successive application of group II and group III phages.

<p>Each experiment was performed in triplicate. For better clarity, only mean values without standard deviations are shown.</p

Resistance frequencies in vivo.

1<p>Ten isolates of each chicken were investigated.</p>2<p>The number of phage susceptible isolates is given in brackets.</p>3<p>One chicken died during the adaption phase.</p><p>Resistance frequencies in vivo.</p

Host range of group II and group III campylophages.

1<p>None of the other <i>Campylobacter</i> species: <i>C. lari</i> (n = 5), <i>C. fetus</i> (n = 2), <i>C. sputorum</i> (n = 2) and <i>C. hyointestinales</i> (n = 1) was lysed by the phages.</p><p>Host range of group II and group III campylophages.</p