Antibiotics Act with vB_AbaP_AGC01 Phage against Acinetobacter baumannii in Human Heat-Inactivated Plasma Blood and Galleria mellonella Models.

Piotr Golec,Bartosz Wojciuk,Natalia Łubowska,Bartłomiej Grygorcewicz,Rafał Rakoczy,Barbara Dołęgowska,Martyna Górska,Daria Śleboda-Taront,Joanna Jursa-Kulesza,Marta Roszak

doi:10.3390/ijms21124390

Abstract

Increasing multidrug resistance has led to renewed interest in phage-based therapy. A combination of the bacteriophages and antibiotics presents a promising approach enhancing the phage therapy effectiveness. First, phage candidates for therapy should be deeply characterized. Here we characterize the bacteriophage vB_AbaP_AGC01 that poses antibacterial activity against clinical Acinetobacter baumannii strains. Moreover, besides genomic and phenotypic analysis our study aims to analyze phage–antibiotic combination effectiveness with the use of ex vivo and in vivo models. The phage AGC01 efficiently adsorbs to A. baumannii cells and possesses a bacteriolytic lifecycle resulting in high production of progeny phages (317 ± 20 PFU × cell−1). The broad host range (50.27%, 93 out of 185 strains) against A. baumannii isolates and the inability of AGC01 to infect other bacterial species show its high specificity. Genomic analysis revealed a high similarity of the AGC01 genome sequence with that of the Friunavirus genus from a subfamily of Autographivirinae. The AGC01 is able to significantly reduce the A. baumannii cell count in a human heat-inactivated plasma blood model (HIP-B), both alone and in combination with antibiotics (gentamicin (GEN), ciprofloxacin (CIP), and meropenem (MER)). The synergistic action was observed when a combination of phage treatment with CIP or MER was used. The antimicrobial activity of AGC01 and phage-antibiotic combinations was confirmed using an in vivo larva model. This study shows the greatest increase in survival of G. mellonella larvae when the combination of phage (MOI = 1) and MER was used, which increased larval survival from 35% to 77%. Hence, AGC01 represents a novel candidate for phage therapy. Additionally, our study suggests that phages and antibiotics can act synergistically for greater antimicrobial effect when used as combination therapy.

Highlights

The rising incidence of multi- and pan-drug resistant bacterial strains poses a severe challenge to medical care worldwide [1,2]
The majority of drug-resistant infection is associated with members of the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) group [3]
According to the WHO list of antibiotic-resistant bacteria, carbapenem-resistant A. baumannii poses a critical threat to public health, with limited therapeutic options

Summary

Introduction

The rising incidence of multi- and pan-drug resistant bacterial strains poses a severe challenge to medical care worldwide [1,2]. According to the WHO list of antibiotic-resistant bacteria, carbapenem-resistant A. baumannii poses a critical threat to public health, with limited therapeutic options. The WHO has highlighted the need to prioritize research on the development of new antibiotics and alternative treatment options for the listed drug-resistant bacteria [4]. A. baumannii causes one of the most challenging nosocomial infections, with mortality rates as high as 35% [5]. This bacterium is responsible for a large spectrum of hospital-acquired infections such as bacteremia, sepsis, urinary tract infection, pneumonia, and burn wound infections, and has developed resistance to almost all known antibiotics [6]. One of the most promising tools in combatting antibiotic-resistant bacteria is the use of bacteriophages, viruses that infect bacteria [7]

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