Isolation and characterization of Acinetobacter phage vAbaIN10 active against carbapenem-resistant Acinetobacter baumannii (CRAB) isolates from healthcare-associated infections in Dakar, Senegal

Abstract

Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) is a critical antimicrobial resistance threat and a WHO-prioritized pathogen. With intrinsic resistance to multiple antibiotics and the emergence of pan-resistant isolates, CRAB infections are challenging to treat, often relying on polymyxins, tigecycline, aminoglycosides, or combinations, though co-resistance is rising globally. Phage therapy is considered as a potential treatment for multidrug-resistant A. baumannii. This study focused on isolating and characterizing phages active against CRAB strains from healthcare-associated infections in Dakar, Senegal. Methods: A lytic phage, Acinetobacter vAbaIN10, was isolated from wastewater collected at the Aristide Le Dantec Hospital in Dakar, Senegal. Isolation, host range, efficiency of plating, temperature and pH stability, lysis kinetics, one-step growth test, sequencing, and genomic analysis were performed. Results: Phage vAbaIN10 belongs to the class Caudoviricetes and the genus Friunavirus. Its genome is 40,279 bp in size. Phage vAbaIN10 is stable across a wide pH range (3–9) and temperature range (25°C–60°C). The phage's lytic activity was evaluated at different multiplicities of infection (MOI): MOI 10, 1, and 10⁻¹. All MOIs significantly reduced the growth of host bacteria. The one-step growth curve showed that vAbaIN10 had a latency period of 25 min and a burst size of approximately 4.78 × 10³ phages per infected bacterial cell. No tRNA, mtRNA, clustered regularly interspaced short palindromic repeat, virulence factors, or antibiotic resistance genes were found in the genome. Conclusions: The biological and genomic characteristics of vAbaIN10 meet the requirements for its potential use in phage therapy.