Bacteriophage D2SVT exhibits potent antimicrobial and antibiofilm activity against carbapenem-resistant Acinetobacter...

Bacteriophages have emerged as a therapeutic option to treat multidrug-resistant (MDR) bacteria, including carbapenem-resistant Acinetobacter baumannii (CRAB). This study reports the identification and characterization of bacteriophage D2SVT, which was effective and specific against CRAB.

Thirty-five collected samples were tested for antibacterial activity against CRAB. The D2SVT phage exhibited significant lytic activity, forming larger zones and clearer plaques than the Acinetobacter phage PBAB132 in spot assays. Growth kinetics assays, CFU plating, 3,5-dinitrosalicylic acid assays, reactive oxygen species (ROS) assays, protein carbonylation assays, and membrane damage assays confirmed D2SVT's specificity to CRAB and its superior efficacy over PBAB132. Characterization using scanning electron microscopy, transmission electron microscopy, confocal microscopy, and flow cytometry revealed CRAB membrane disruption, reduced viability, and phage-cell interaction. D2SVT also exhibited anti-biofilm activity, as observed in scanning electron microscopy (SEM) analysis. D2SVT also reduced the infection of CRAB in the A549 cell line. No non-specific effects were observed on E. coli, B. subtilis, and Lactobacillus. Transmission electron microscopy (TEM) analysis classified D2SVT as a short-tailed phage with icosahedral capsid geometry (hexagonal head structure), placing it within the Caudoviricetes family. Whole genome sequencing has identified it as a phage that is closely related to phage PhiE11, and its sequence was submitted to the National Centre for Biotechnology Information (NCBI).

Bacteriophage D2SVT is highly specific and effective against CRAB, demonstrating strong lytic activity and anti-biofilm properties that support its potential for phage therapy.