Broad host range phages target globalbacterial strains and clear infection in five-strain model systems.

Abstract

UNLABELLED: is a prevalent bacterial pathogen in poultry, and due to the spread of antimicrobial resistance, alternative treatments are needed to prevent and treat infection. Bacteriophages (phages), viruses that kill bacteria, offer a viable option and can be used therapeutically to treatinfections. The aim of this study was to isolate phages againststrains currently circulating on farms across the world and establish their virulence and development potential using host range screening, virulence assays, and larva infection studies. We isolated 32 phages of which 19 lysed 80%-92% of our globalpoultry strain collection (= 97). The virulence of these individual phages and 32 different phage combinations was quantified in liquid culture at multiple doses. We then developed a multi-strainlarva infection model, to mimic an effective poultry model used by the industry. We tested the efficacy of 16/32 phage cocktails in the larva model. From this, we identified that our phage cocktail consisting of phages CPLM2, CPLM15, and CPLS41 was the most effective at reducingcolonization in infected larvae when administered before bacterial challenge. These data suggest that phages do have significant potential to prevent and treatinfection in poultry. IMPORTANCE: causes foodborne illness worldwide, and 95% of human infections are linked to the consumption of contaminated meat, including chicken products. In poultry,infection causes necrotic enteritis, and associated mortality rates can be up to 50%. However, treating infections is difficult as the bacterium is becoming antibiotic-resistant. Furthermore, the poultry industry is striving toward reduced antibiotic usage. Bacteriophages (phages) offer a promising alternative, and to progress this approach, robust suitable phages and laboratory models that mimicinfections in poultry are required. In our study, we isolated phages targetingand found that many lysestrains isolated from chickens worldwide. Consistent with other published studies, in the model systems we assayed here, when some phages were combined as cocktails, the infection was cleared most effectively compared to individual phage use.