| Abstrakt: |
Within the global endeavours to reduce antibiotic resistances and protect human and animal health, novel antimicrobials are urgently required (WHO, 2022a). In the WHO report on clinical development against priority pathogens 2022, nine out of 34 non-traditional antimicrobials were bacteriophages or bacteriophage-based products (WHO, 2022b). Bacteriophages (phages) are the natural enemies of bacteria, they can infect their host bacteria, replicate inside the bacterial cell and finally kill bacteria by lysis. Their therapeutic potential for reducing bacterial pathogens in birds has been shown in several studies (KITTLER et al., 2017). Due to their mode of action, phages meet all innovation criteria of the WHO, belonging to a new chemical class, having new molecular targets and showing no cross resistance to other antibiotic classes. They have been used against Campylobacter in several in vivo trials and two field trials in commercial broiler houses (KITTLER et al., 2013; CHINIVASAGAM et al., 2020). While phage resistance in Campylobacter was associated with fitness costs in some experiments, the occurrence of new bacterial strains that are not sensitive to the bacteriophages used, was suggested to reduce phage effectiveness and reproducibility under field conditions. Thus, phages were combined with other measures in a multiple-hurdle approach in a seeder bird model (PEH et al., 2024) and under field conditions (BOGUN et al., 2024). The application of a Fletchervirus phage NCTC 12673 and Firehammervirus phage vB_CcM-LmqsCPL1/1 in a field trial, resulted in reductions of up to 1.1 log10 CFU/ml in fecal samples 1 day after dosing. Combined application of the phages with curcumin via feed and an organic acid blend via drinking water did not result in higher reductions than phage application alone. Based on these results, no synergism of the combined application was observed. However, after combined application of the phages with a competitive exclusion culture in a seeder bird model, increased reduction compared to single used measures has been observed. [ABSTRACT FROM AUTHOR] |
