Isolation and characterization of a novel phage AbT1 and evaluating its anti-biofilm activity and antibiotic synergy

Abstract Acinetobacter baumannii represents a formidable multidrug-resistant pathogen in healthcare settings. The increase in antimicrobial resistance had led to renewed interest in phage therapy, an approach based on the natural predatory interactions of phages. In this study, a novel phage, AbT1, specific to A. baumannii ATCC 17978, was isolated and subjected to comprehensive characterization. Phage AbT1 demonstrated considerable stability across a broad range of temperatures and pH values, in addition to exhibiting potent lytic activity against A. baumannii isolates. Genomic analysis indicated that phage AbT1 belonged to the Caudoviricetes class and possessed a double-stranded DNA genome of 53,410 bp, containing 78 open reading frames (ORFs). Among these, 29 ORFs were predicted to encode structural or functional proteins. Furthermore, neutralization of A. baumannii-induced cytotoxicity in host cells was observed following treatment with phage AbT1. This investigation also underscored the potential of phage AbT1 in disrupting biofilms formed by A. baumannii. Notably, compared with a single treatment, the combined use of phage AbT1 and antibiotics consistently enhanced the bactericidal effect. Thus, this study emphasized the therapeutic potential of phage AbT1 and offered valuable insights into the treatment of A. baumannii infections through phage-based approaches.