Discovery, Induction, and Screening of Prophages in Clinical Acinetobacter baumannii Isolates

Background: Acinetobacter baumannii is a common bacterial pathogen in nosocomial infections. It has become one of the greatest threats to human health for its growing resistance to “last resort” antibiotics, which has led to a revival of phage therapy as a potential treatment. However, conventional methods for isolating A. baumannii -infecting phages are labor-intensive and often unsuccessful. Methods: Our approach involves a computational pipeline to identify temperate phages (prophages) integrated into A. baumannii genomes, followed by mitomycin C (MMC) induction of those strains to screen for active prophages. Results: Here we show a prophage analysis for nearly 900 A. baumannii genomes. We observed MMC-triggered excision of nine prophages from eight A. baumannii strains by Polymerase Chain Reaction (PCR) and sequencing. Further, we show four prophage-formed virions detectable by transmission electron microscopy and two that can plaque on other A. baumannii isolates. Conclusion: This work demonstrates the utility and diversity of prophages for further development as therapeutics for antibiotic-resistant A. baumannii .