PhageScore-based analysis of Acinetobacter baumannii infecting phages antibiotic interaction in liquid medium.

The growing interest in bacteriophages and antibiotics' combined use poses new challenges regarding this phenomenon's accurate description. This study aimed to apply the PhageScore methodology to assess the phage-antibiotic combination activity in liquid bacterial culture. For this purpose, previously described Acinetobacter infecting phages vB_AbaP_AGC01, Aba-1, and Aba-4 and antibiotics (gentamicin, ciprofloxacin, meropenem, norfloxacin, and fosfomycin) were used to obtain a lysis curve of bacteriophages under antibiotic pressure. The experimental data were analyzed using the Fractional Inhibitory Concentration Index (FICI) and PhageScore methodology. The results obtained by this method clearly show differences between phage lytic activity after antibiotic addition. Thus, we present the potential use of the PhageScore method as a tool for characterizing the phage antibiotic synergy in liquid culture. Further, the optimization of the PhageScore for this purpose can help compare antibiotics and their outcome on bacteriophage lytic activity.