Strategic combination of bacteriophages with highly susceptible cells for enhanced intestinal settlement and resistant cell killing

• Published in: Biochemical and biophysical research communications 2024-05, Vol.709, p.149823, Article 149823
• Main Authors: Ha, Eun-Jin, Hong, Seung-Min, Kim, Tae-Eun, Cho, Sun-Hee, Ko, Dae-Sung, Kim, Jae-Hong, Choi, Kang-Seuk, Kwon, Hyuk-Joon
• Format: Article
• Language: English
• Subjects: Animals; Bacteriophage therapy; Bacteriophages - genetics; Cell Death; Chickens; Coliphages; Enhanced resistance cell killing; Escherichia coli - genetics; Escherichia coli Infections; O78 serogroup avian pathogenic E. coli; Phage shedding; Phage susceptibility; Poultry Diseases - therapy
• ISSN: 0006-291X; 1090-2104; 1090-2104
• DOI: 10.1016/j.bbrc.2024.149823

Avian pathogenic Escherichia coli (APEC) causes enormous economic losses and is a primary contributor to the emergence of multidrug resistance (MDR)-related problems in the poultry industry. Bacteriophage (phage) therapy has been successful in controlling MDR, but phage-resistant variants have rapidly emerged through the horizontal transmission of diverse phage defense systems carried on mobile genetic elements. Consequently, while multiple phage cocktails are recommended for phage therapy, there is a growing need to explore simpler and more cost-effective phage treatment alternatives. In this study, we characterized two novel O78-specific APEC phages, φWAO78-1 and φHAO78-1, in terms of their morphology, genome, physicochemical stability and growth kinetics. Additionally, we assessed the susceptibility of thirty-two O78 APEC strains to these phages. We analyzed the roles of highly susceptible cells in intestinal settlement and fecal shedding (susceptible cell-assisted intestinal settlement and shedding, SAIS) of phages in chickens via coinoculation with phages. Furthermore, we evaluated a new strategy, susceptible cell-assisted resistant cell killing (SARK), by comparing phage susceptibility between resistant cells alone and a mixture of resistant and highly susceptible cells in vitro. As expected, high proportions of O78 APEC strains had already acquired multiple phage defense systems, exhibiting considerable resistance to φWAO78-1 and φHAO78-1. Coinoculation of highly susceptible cells with phages prolonged phage shedding in feces, and the coexistence of susceptible cells markedly increased the phage susceptibility of resistant cells. Therefore, the SAIS and SARK strategies were demonstrated to be promising both in vivo and in vitro. •RST4-4 and RST21-1 O78 APEC strains are more resistant to phages than RST3-1 strains.•O78 phage-resistant APEC strains share a variety of multiple phage defense systems.•Highly susceptible cell co-inoculation facilitates prolonged phage shedding in feces.•Highly susceptible cell coexistence increases resistant cell killing of phage steeply.