Genomic and functional characterization of novel phages targeting multidrug-resistant Acinetobacter baumannii

Authors: OROZCO-OCHOA, ALMA - Center For Research In Food And Development (CIAD); Quinones, Beatriz; GONZALEZ-GOMEZ, JEAN - Center For Research In Food And Development (CIAD); CASTRO DEL CAMPO, NOHELIA - Center For Research In Food And Development (CIAD); VALDEZ-TORRES, JOSE - Center For Research In Food And Development (CIAD); CHAIDEZ, CRISTOBAL - Center For Research In Food And Development (CIAD)

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2025
Publication Date: 6/26/2025
Citation: Orozco-Ochoa, A.K., Quinones, B., Gonzalez-Gomez, J.P., Castro Del Campo, N., Valdez-Torres, J.B., Chaidez, C. 2025. Genomic and functional characterization of novel phages targeting multidrug-resistant Acinetobacter baumannii. International Journal of Molecular Sciences. 26(13). Article 6141. https://doi.org/10.3390/ijms26136141.
DOI: https://doi.org/10.3390/ijms26136141

Interpretive Summary: The misuse and overuse of antimicrobial agents against bacterial pathogens have accelerated the emergence of antimicrobial resistance, a major global health concern. Acinetobacter baumannii is a top-priority opportunistic bacterial pathogen and has been significantly implicated in human infections due to the rapid acquisition of resistance determinants. In recent years, the use of bacteriophages has become a promising intervention strategy to combat antimicrobial resistance among bacterial pathogens. Although a few phages capable of infecting A. baumannii have been previously identified, these phages are limited in their host range, stability, and bacterial defense evasion. Given the growing concern over antimicrobial resistance, the present study conducted a genomic and functional characterization of novel temperate and lytic phages and demonstrated the effective and targeted use of these alternative antimicrobial agents against multidrug-resistant strains of A. baumannii.

Technical Abstract: Acinetobacter baumannii is an opportunistic pathogen and a leading cause of nosocomial infections worldwide. As conventional antimicrobial treatments become less effective, the use of bacteriophages emerge as a promising alternative. To expand the available phage libraries, eight phages targeting multidrug-resistant A. baumannii were isolated for detailed genomic and functional characterization. Comparative genomics and phylogenetic analyses revealed that all eight phages (AKO8a, PS118, B612, MCR, IDQ7, 89P13, CRL20, and CIM23) lacked virulence or antibiotic resistance genes and were classified as novel species within the Kagunavirus genus. The lysogenic phages PS118, B612, IDQ7, 89P13, and CIM23 harbored a putative regulatory immunity protein (QCF69_gp43). By contrast, in vitro tests confirmed that phages AKO8a, MCR, and CRL20 exhibited an exclusive lytic cycle. Subsequent antibacterial activity assays showed a 63–72% reduction in the growth of multidrug-resistant A. baumannii strain AbAK04 at multiplicities of infection of 0.1, 1, and 10 for the examined lytic phages. Notably, the lytic phage MCR encoded a glycosyl hydrolase family 58 (GH58) enzyme, implicated in potentiating the antibacterial effect. These findings highlight the alternative use of phages, particularly phage MCR, as novel antimicrobial agents against multidrug-resistant strains of A. baumannii and provide fundamental information for the development of phage therapy applications.