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

Background: Acinetobacter baumannii, particularly carbapenem-resistant strains (CRAB), poses a major concern in the fight against antimicrobial resistance (AMR), identified as a top-priority pathogen by the World Health Organization (WHO). A. baumannii has intrinsic resistance to several antibiotics, including penicillin, cephalosporins, chloramphenicol, and fosfomycin, but the development of AMR has led to the emergence of extremely drug-resistant and pan-resistant isolates. Treatment of CRAB infections often relies on polymyxins, tigecycline, aminoglycosides, and their combinations. However, co-resistance to these antibiotics is increasingly reported worldwide. Phage therapy is now being reconsidered as a promising approach to treat infections caused by multidrug-resistant A. baumannii, particularly those posing therapeutic challenges. This study aimed to isolate and characterize phages active against CRAB strains isolated from HAIs 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 (EOP), 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 to 9) and temperature range (25°C to 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 minutes and a burst size of approximately 4.78 × 10³ phages per infected bacterial cell. No tRNA, mtRNA, CRISPR, virulence factors, or antibiotic resistance genes were found in the genome.

Conclusion: The biological and genomic characteristics of vAbaIN10 meet the requirements for its potential use in phage therapy.