A bacteriophage with dual host specificity for canine and porcine Bordetella bronchiseptica: Characterization and biofilm disruption potential.

Bordetella bronchiseptica is a pathogen responsible for canine infectious tracheobronchitis (kennel cough) and porcine atrophic rhinitis, and it can cause respiratory infections in a variety of mammalian hosts. In recent years, the extensive use of antibiotics has resulted in increasingly severe antibiotic resistance, consequently driving significant interest in bacteriophages as a potential alternative to antibiotics. In this study, bacteriophage PBb001 isolated from swine farm wastewater in Yantai, Shandong, exhibited lytic activity against Bordetella bronchiseptica, including strains derived from canine and swine hosts. Bacteriophage PBb001 exhibited a latent period of 30 min and a burst size of approximately 323 plaque-forming units (PFU) per cell. The phage exhibited robust stability across a temperature range of 4-60 °C and pH conditions of 3-11, with an optimal multiplicity of infection (MOI) of 0.1. Genomic analysis revealed that PBb001 possesses a linear double-stranded DNA genome of 44,808 bp, with no lysogeny genes, virulence factors, or antibiotic resistance genes detected. In vitro antibacterial assays showed that PBb001 significantly reduced optical density (OD600, reflecting bacterial growth inhibition) and viable bacterial counts in planktonic cultures. Additionally, PBb001 effectively suppressed biofilm formation and disrupted pre-existing biofilms, as evidenced by reduced OD595 values and decreased viable bacterial counts in biofilm-associated assays. These results collectively suggest that PBb001 holds significant potential for controlling B. bronchiseptica infections and represents a potential candidate for further development as an antibiotic alternative.