Characterization and complete genome sequence analysis of two Myoviral bacteriophages infecting clinical carbapenem-resistant Acinetobacter baumannii isolates

Aims: The aim of this study was to characterize phenotypical properties, to analyse whole genomes of novel Acinetobacter baumannii phages infecting carbapenem-resistant Ac. baumannii (CRAB) and to evaluate their potential as antimicrobial alternatives to control Ac. baumannii in clinical settings. Methods and Results: The Ac. baumannii phages, Βϕ-R1215 and Βϕ-R2315, were isolated from sewage samples. These phages were characterized by transmission electron microscopy, host spectrum, the thermal/pH stability test, the bacterial lysis assay and the whole genome analysis. Both phages lysed 21 of 45 CRAB hosts, and showed high stability at various pH (pH 4–10) and temperature (25–60°C), and were strongly active against host bacteria in vitro. The genomes of Βϕ-R1215 and Βϕ-R2315 are linear double-strands of DNA with 44·866 and 44·846 bp respectively. These two genomes revealed high similarity at the DNA level, but the organization and direction of open reading frames were different. Conclusions: The Ac. baumannii phages, Βϕ-R1215 and Βϕ-R2315, are novel lytic phages lysing CRAB strains which were isolated from respiratory samples of patients. Significance and Impact of the Study: In vitro and in silico data showed that these novel Ac. baumannii phages, Βϕ-R1215 and Βϕ-R2315, have potential as antimicrobial alternatives to control CRAB in healthcare settings.