Evaluation of Potential ARG Packaging by Two Environmental T7-Like Phage during Phage-Host Interaction.

The increase in antimicrobial resistance is a threat to both human and animal health. The transfer of antibiotic resistance genes (ARG) via plasmids has been studied in detail whereas the contribution of bacteriophage-mediated ARG transmission is relatively little explored. We isolated and characterized two T7-like lytic bacteriophages that infected multidrug-resistant hosts. The morphology and genomic analysis indicated that both phage HZP2 and HZ2R8 were evolutionarily related and their genomes did not encode ARGs. However, ARG-like raw reads were detected in offspring sequencing data with a different abundance level implying that potential ARG packaging had occurred. PCR results demonstrated that six fragments of genes (, , , , , ) were potentially packaged by phage HZP2 and four (, , , ) by phage HZ2R8. Further quantitative results showed that ARG abundance hierarchies were similar. The gene was the most abundant (up to 1.38 × 10 copies/mL) whereas and were the least. Moreover, the clinically important gene was the second most abundant ARG indicating a possibility for spread through generalized transduction. Together, our results indicated that these structurally similar phage possessed similar characteristics and potential packaging during phage-host interaction displayed an ARG preference rather than occurring randomly.