Therapeutic effect and anti-biofilm ability assessment of a novel phage, phiPA1-3, against carbapenem-resistant Pseudomonas aeruginosa

The high efficiency protective effectiveness of a newly isolated myoviruses bacteriophage vB_AceP_PAc in protecting mice from Aeromonas caviae infection in mice

Phage therapy is an effective strategy to combat multidrug resistance in bacteria and has been increasingly utilized to protect animals from bacterial infections. This study involved the isolation and purification of a novel myoviruses phage, vB_AceP_PAc, from a drug-resistant bacterial strain Aeromonas caviae. Genome sequence analysis based on nucleotide sequences revealed that vB_AceP_PAc shared significant similarity with the genomes of 10 other Aeromonas phages, with the highest coverage rate of 52% with phiA047. Intraperitoneal injection of 1 × 10⁷ CFU/mL (100 µL/mouse) A. caviae AC-CY resulted in diarrhea in mice three days later. At this time, oral administration of 1 × 109 PFU/mL (100 µL/mouse) vB_AceP_PAc effectively alleviated the diarrhea induced by Pseudomonas aeruginosa infection in the mice. Furthermore, oral administration of 1 × 109 PFU/ml vB_AceP_PAc (100 µl/mouse) in healthy mice significantly reduced inflammatory cytokine levels, increased tight junction molecule levels, and improved intestinal barrier function. Moreover, the consumption of vB_AceP_PAc by health mice led to a significant increase in the abundance of Lactobacillaceae in the gut, while the expression of CD3+CD4+/CD3+CD8+ was minimally affected. Overall, the findings of this study confirmed the promising potential of bacteriophage vB_AceP_PAc in treating diarrhea caused by A. caviae.

Characterization and genomic analysis of a jumbo phage, PG216, with broad lytic activity against several Vibrio species

In this study, a lytic phage, named PG216, was obtained from seawater collected in Qingdao, using Vibrio parahaemolyticus strain G299 as its host. Transmission electron microscopy revealed that phage PG216 has an icosahedral head with a diameter of 100 ± 6.7 nm and a contractible tail with a length of 126 ± 6.7 nm. The spot assay and EOP assay for host range testing revealed that the phage displayed extensive lytic activity against five Vibrio species: V. alginolyticus, V. parahaemolyticus, V. vulnificus, V. mimicus, and V. harveyi. The one-step growth curve indicated that the phage has a latent period of 25 min, a lysis duration of 115 min, and an average burst size of 135 ± 02 PFU/cell. The genome of PG216 is 244,027 bp in length with a GC content of 42.89%, and itcontains383 ORFs and encodes 28 tRNAs. Phylogenetic analysis suggested that PG216 belongs to the genus Schizotequatrovirus within the family Straboviridae. Phage PG216 was found to be able to eradicate mature biofilms produced by V. parahaemolyticus G299. Phage PG216 demonstrates notable lytic activity while lacking virulence and antibiotic-resistance genes and therefore might be a viable candidate for use in phage therapy of vibriosis.

Therapeutic and Diagnostic Potential of a Novel K1 Capsule Dependent Phage, JSSK01, and Its Depolymerase in Multidrug-Resistant Escherichia coli Infections

Bacteriophages are viruses that have the potential to combat bacterial infections caused by antimicrobial-resistant bacterial strains. In this study, we investigated a novel lytic bacteriophage, vB_EcoS_JSSK01, isolated from sewage in Hualien, Taiwan, which effectively combats multidrug-resistant (MDR) Escherichia coli of the K1 capsular type. K1 E. coli is a major cause of severe extraintestinal infections, such as neonatal meningitis and urinary tract infections. Phage JSSK01 was found to have a genome size of 44,509 base pairs, producing approximately 123 particles per infected cell in 35 min, and was highly stable across a range of temperatures and pH. JSSK01 infected 59.3% of the MDR strains tested, and its depolymerase (ORF40) specifically degraded the K1 capsule in these bacteria. In a zebrafish model, JSSK01 treatment after infection significantly improved survival, with survival in the treated group reaching 100%, while that in the untreated group dropped to 10% after three days. The functional activity of depolymerase was validated using zone inhibition and agglutination tests. These results indicate that JSSK01 and its substrate-specific depolymerase have promising therapeutic and diagnostic applications against K1-encapsulated MDR E. coli infections.

In Vitro and In Vivo Assessments of Newly Isolated N4-like Bacteriophage against ST45 K62 Capsular-Type Carbapenem-Resistant Klebsiella pneumoniae: vB_kpnP_KPYAP-1

The rise of carbapenem-resistant Klebsiella pneumoniae (CRKP) presents a significant global challenge in clinical and healthcare settings, severely limiting treatment options. This study aimed to utilize a bacteriophage as an alternative therapy against carbapenem-resistant K. pneumoniae. A novel lytic N4-like Klebsiella phage, vB_kpnP_KPYAP-1 (KPYAP-1), was isolated from sewage. It demonstrated efficacy against the K62 serotype polysaccharide capsule of blaOXA-48-producing K. pneumoniae. KPYAP-1 forms small, clear plaques, has a latent period of 20 min, and reaches a growth plateau at 35 min, with a burst size of 473 plaque-forming units (PFUs) per infected cell. Phylogenetic analysis places KPYAP-1 in the Schitoviridae family, Enquatrovirinae subfamily, and Kaypoctavirus genus. KPYAP-1 employs an N4-like direct terminal repeat mechanism for genome packaging and encodes a large virion-encapsulated RNA polymerase. It lacks integrase or repressor genes, antibiotic resistance genes, bacterial virulence factors, and toxins, ensuring its safety for therapeutic use. Comparative genome analysis revealed that the KPYAP-1 genome is most similar to the KP8 genome, yet differs in tail fiber protein, indicating variations in host recognition. In a zebrafish infection model, KPYAP-1 significantly improved the survival rate of infected fish by 92% at a multiplicity of infection (MOI) of 10, demonstrating its potential for in vivo treatment. These results highlight KPYAP-1 as a promising candidate for developing phage-based therapies targeting carbapenemase-producing K. pneumoniae.

Characterization of the novel broad-spectrum lytic phage Phage_Pae01 and its antibiofilm efficacy against Pseudomonas aeruginosa

Introduction

Pseudomonas aeruginosa is present throughout nature and is a common opportunistic pathogen in the human body. Carbapenem antibiotics are typically utilized as a last resort in the clinical treatment of multidrug-resistant infections caused by P. aeruginosa. The increase in carbapenem-resistant P. aeruginosa poses an immense challenge for the treatment of these infections. Bacteriophages have the potential to be used as antimicrobial agents for treating antibiotic-resistant bacteria.

Methods and Results

In this study, a new virulent P. aeruginosa phage, Phage_Pae01, was isolated from hospital sewage and shown to have broad-spectrum antibacterial activity against clinical P. aeruginosa isolates (83.6%). These clinical strains included multidrug-resistant P. aeruginosa and carbapenem-resistant P. aeruginosa. Transmission electron microscopy revealed that the phage possessed an icosahedral head of approximately 80 nm and a long tail about 110  m, indicating that it belongs to the Myoviridae family of the order Caudovirales. Biological characteristic analysis revealed that Phage_Pae01 could maintain stable activity in the temperature range of 4~ 60°C and pH range of 4 ~ 10. According to the in vitro lysis kinetics of the phage, Phage_Pae01 demonstrated strong antibacterial activity. The optimal multiplicity of infection was 0.01. The genome of Phage_Pae01 has a total length of 93,182 bp and contains 176 open reading frames (ORFs). The phage genome does not contain genes related to virulence or antibiotic resistance. In addition, Phage_Pae01 effectively prevented the formation of biofilms and eliminated established biofilms. When Phage_Pae01 was combined with gentamicin, it significantly disrupted established P. aeruginosa biofilms.

Conclusion

We identified a novel P. aeruginosa phage and demonstrated its effective antimicrobial properties against P. aeruginosa in both the floating and biofilm states. These findings offer a promising approach for the treatment of drug-resistant bacterial infections in clinical settings.

Therapeutic Potential of a Novel Lytic Phage, vB_EclM_ECLFM1, against Carbapenem-Resistant Enterobacter cloacae

The global rise of multidrug-resistant Enterobacter cloacae strains, especially those that are resistant to carbapenems and produce metallo-β-lactamases, poses a critical challenge in clinical settings owing to limited treatment options. While bacteriophages show promise in treating these infections, their use is hindered by scarce resources and insufficient genomic data. In this study, we isolated ECLFM1, a novel E. cloacae phage, from sewage water using a carbapenem-resistant clinical strain as the host. ECLFM1 exhibited rapid adsorption and a 15-min latent period, with a burst size of approximately 75 PFU/infected cell. Its genome, spanning 172,036 bp, was characterized and identified as a member of Karamvirus. In therapeutic applications, owing to a high multiplicity of infection, ECLFM1 showed increased survival in zebrafish infected with E. cloacae. This study highlights ECLFM1's potential as a candidate for controlling clinical E. cloacae infections, which would help address challenges in treating multidrug-resistant strains and contribute to the development of alternative treatments.