Bacteriophage therapy for challenging bacterial infections: achievements, limitations and prospects for future clinical use by veterinary dermatologists

Therapeutic potential of a newly isolated bacteriophage against multi-drug resistant Enterococcus faecalis infections: in vitro and in vivo characterization

BACKGROUND

In nosocomial settings, vancomycin-resistant Enterococcus faecalis is a major health threat leading to increased morbidities, mortalities, and treatment costs. Nowadays, several approaches are under investigation to enhance the activity of or replace the traditional antibiotics. Bacteriophage therapy was sought as a potential approach for combating E. faecalis infections. The present study focuses on isolating and characterizing bacteriophage against clinical multi-drug resistant (MDR) E. faecalis strain Lb-1492. The phage stability, lytic activity, host-range, latent period, burst size, the ability to detach the pre-formed biofilm and destroy entrapped cells were investigated. The phage genome was purified, sequenced, and subjected to bioinformatics analysis for identifying and characterizing its features, as well as, the suitability for clinical application. Finally, the ability of the phage to rescue mice from deadly, experimentally induced E. faecalis bacteremia was evaluated.

RESULTS

A virulent phage was isolated from sewage water against a clinical MDR E. faecalis isolate. Morphological and genomic studies indicated that the phage belongs to the Efquatrovirus genus, with a long tail, icosahedral head and a linear double-stranded DNA genome of approximately 42.9 kbp. The phage was named vB_Efa_ZAT1 (shortly ZAT1). It demonstrated a shorter latent period and larger burst size than regular-tailed phages, and a characteristic stability over a wide range of pH and temperatures, with the optimum activity at pH 7.4 and 37 °C, respectively. Phage ZAT1 showed a narrow spectrum of activity and a characteristic biofilm disruption ability. The phage managed successfully to control E. faecalis-induced bacteremia in mice models, which was lethal within 48 h in the control group. An intraperitoneal injection of 3 × 108 PFU of the phage solution given 1 h after the bacterial challenge was sufficient to save all the animals, completely reversing the trend of 100% mortality caused by this bacterium.

CONCLUSIONS

Phage therapy can be a promising alternative to traditional antibiotics in the post-antibiotic era with a significant antimicrobial and antibiofilm activities against MDR E. faecalis.

Efficacy of bacteriophages with Aloe vera extract in formulated cosmetics to combat multidrug-resistant bacteria in skin diseases

Phage therapy offers a promising alternative to antibiotic treatment for combating illnesses caused by multidrug-resistant bacteria. In this study, pathogenic bacteria Staphylococcus aureus and Pseudomonas aeruginosa were isolated from pus and skin infected fluidsusing selective media. These bacterial isolates were biochemically identified as S. aureus and P. aeruginosa with probabilities of 98% and 99%, respectively, through VITEK2 system, and were confirmed as multidrug-resistant based on minimum inhibitory concentration test using colorimetric reagent cards. Lytic phages specific to these isolates were isolated, identified through plaque assays, transmission electron microscopy and classified morphologically according to the new International Committee on Taxonomy of Viruses classification as members of the Straboviridae, Drexlerviridae, and Autographiviridae families. A cosmetic gel formulation combining Aloe vera extract and the phage cocktail was prepared and tested. This gel significantly enhanced phage longevity and reduced bacterial growth by 95.5% compared to the reductions of 90.5% with Aloe Vera extract alone and 45.7% with the basic cosmetic gel. The phage remained effective for 4 to over 12 weeks after being preserved in the cosmetic formula, maintaining populations ranging from 5 × 103 to 25 × 104 PFU/mL in vitro. These findings highlight the potential of phage-based formulations, such as Vena Skin Gel, as innovative biotherapeutic tools for managing skin infections.

Phage Engineering for Targeted Multidrug-Resistant Escherichia coli

The lytic bacteriophages have potential application value in the treatment of bacterial infections. However, the narrow host spectrum of these phages limits their range of clinical application. Here, we demonstrate the use of scarless Cas9-assisted recombination (no-SCAR) gene-editing technology to regulate phage-host range. We used phage PHB20 as the scaffold to create agents targeting different multidrug-resistant Escherichia coli by replacing its phage tail fiber gene (ORF40). The engineered phages were polyvalent and capable of infecting both the original host bacteria and new targets. Phage-tail fiber genes can be amplified by PCR to construct a recombinant phage PHB20 library that can deal with multidrug-resistant bacteria in the future. Our results provide a better understanding of phage-host interactions, and we describe new anti-bacterial editing methods.

Phage Products for Fighting Antimicrobial Resistance

Antimicrobial resistance (AMR) has become a global public health issue and antibiotic agents have lagged behind the rise in bacterial resistance. We are searching for a new method to combat AMR and phages are viruses that can effectively fight bacterial infections, which have renewed interest as antibiotic alternatives with their specificity. Large phage products have been produced in recent years to fight AMR. Using the “one health” approach, this review summarizes the phage products used in plant, food, animal, and human health. In addition, the advantages and disadvantages and future perspectives for the development of phage therapy as an antibiotic alternative to combat AMR are also discussed in this review.