Isolation and Characterisation of Bacteriophage Selective for Key Acinetobacter baumannii Capsule Chemotypes

Area of Science:

• Microbiology
• Virology
• Infectious Diseases

Background:

• Multidrug-resistant Acinetobacter baumannii poses a significant threat in healthcare settings.
• Bacteriophage therapy offers a potential alternative to conventional antibiotics.
• Isolation and characterization of novel phages are crucial for developing new antimicrobial strategies.

Purpose of the Study:

• To isolate and characterize bacteriophages effective against multidrug-resistant Acinetobacter baumannii.
• To evaluate the biological properties and genomic features of selected phages.
• To assess the potential of these phages as alternative antibacterial agents.

Main Methods:

• Isolation of bacteriophages from tertiary care hospital sewage.
• Characterization of phage biological properties, including burst size, latent period, adsorption, stability (temperature and pH).
• Whole-genome sequencing, phylogenetic analysis, and protein composition analysis.
• Morphological analysis using electron microscopy.

Main Results:

• Nineteen bacteriophages were isolated against five capsular types of multidrug-resistant A. baumannii.
• Phages T1245, T444, and T515 exhibited excellent biological properties: large burst size (>420 pfu/mL), short latent period (<6 min), rapid adsorption (<10 min), and broad stability (-20 to 60 °C, pH 5.0-9.0).
• Genomic analysis revealed double-stranded DNA (40-50 kb) with 38-39% G+C content and no toxin genes.
• Phylogenetic and morphological studies confirmed T1245, T444, and T515 belong to the Podoviridae family.
• Key enzymes like depolymerase and endolysin were identified.

Conclusions:

• Novel bacteriophages T1245, T444, and T515 demonstrate potent lytic activity against multidrug-resistant A. baumannii.
• Their robust biological characteristics and genetic safety profile make them promising candidates for phage therapy.
• These phages, possessing essential enzymes, represent a viable alternative for controlling A. baumannii infections.