Engineering pH-sensitive erodible chitosan hydrogel composite containing bacteriophage: An interplay between hydrogel and bacteriophage against Staphylococcus aureus

Development of a lytic bacteriophage BPK01 impregnated biopolymer (chitosan) hydrogel for combating high-risk strains of carbapenem resistant Klebsiella pneumoniae (CRKP) pathogens- in vitro and in vivo evaluation

Alternative strategies are urgently required to combat the rise of high-risk carbapenem-resistant Klebsiella pneumoniae (CRKP), including blaNDM-positive strains that produce carbapenemase enzymes, which deactivate beta-lactam antibiotics and result in poor treatment outcomes. In this study, we isolated a bacteriophage BPK01, targeting a high-risk strain of Klebsiella pneumoniae (carbapenem-resistant, blaNDM-positive, ST147, capsular type K64, biofilm former). BPK01 demonstrated strong lytic activity (84%) against a panel of genetically characterized CRKP strains (n = 59) from clinical specimens, including pus, urine, sputum, blood, and tracheal aspirates. BPK01 was classified as a Caudoviricetes phage, exhibiting a burst size of 220 virions and a short latent period of 10 min. It demonstrated stability across a range of conditions (temperature, pH, and organic solvents) and effectively disrupted biofilms on silicone catheters. In vivo, BPK01 improved survival rates in the Galleria mellonella infection model and reduced bacterial burden in a murine bacteremia model, underscoring its therapeutic potential. Subsequently, we developed a hydrogel by incorporating BPK01 into a chitosan biopolymer, which demonstrated efficient lytic activity (spot assay, scanning electron microscopy, time kill assay) against CRKP pathogens, stability of biological activity for 6 months of storage, and controlled release kinetics, with the mathematical model Korsmeyer - Peppas being the best fit (R2 = 0.9962). The hydrogel expedited the healing of CRKP-infected lesions in a murine model, suggesting its potential as an effective topical treatment. This study highlights BPK01 as a promising biotherapeutic candidate for treating CRKP infection, with the phage hydrogel offering an ecofriendly and sustainable solution for treating infected lesions. Further research could expand its use in phage cocktails and other formulations for broader CRKP infection management.

Bacteriophage entrapment strategies for the treatment of chronic wound infections: a comprehensive review

The growing threat of antimicrobial resistance has made the quest for antibiotic alternatives or synergists one of the most pressing priorities of the 21st century. The emergence of multidrug-resistance in most of the common wound pathogens has amplified the risk of antibiotic-resistant wound infections. Bacteriophages, with their self-replicating ability and targeted specificity, can act as suitable antibiotic alternatives. Nevertheless, targeted delivery of phages to infection sites remains a crucial issue, specifically in the case of topical infections. Hence, different phage delivery systems have been studied in recent years. However, there have been no recent reviews of phage delivery systems focusing exclusively on phage application on wounds. This review provides a compendium of all the major delivery systems that have been used to deliver phages to wound infection sites. Special focus has also been awarded to phage-embedded hydrogels with a discussion on the different aspects to be considered during their preparation.

Insights into the Preparation of and Evaluation of the Bactericidal Effects of Phage-Based Hydrogels

The rise of antibiotic-resistant strains demands new alternatives in antibacterial treatment. Bacteriophages, with their precise host specificity and ability to target and eliminate bacteria safely, present a valuable option. Meanwhile, hydrogels, known for their excellent biodegradability and biocompatibility, serve as ideal carriers for bacteriophages. The combination of bacteriophages and hydrogels ensures heightened phage activity, concentration, controlled release, and strong antibacterial properties, making it a promising avenue for antibacterial treatment. This article provides a comprehensive review of different crosslinking methods for phage hydrogels, focusing on their application in treating infections caused by various drug-resistant bacteria and highlighting their effective antibacterial properties and controlled release capabilities.

Optimized Dosing and Delivery of Bacteriophage Therapy for Wound Infections

Lytic bacteriophages, viruses that lyse (kill) bacteria, hold great promise for treating infections, including wound infections caused by antimicrobial-resistant Pseudomonas aeruginosa. However, the optimal dosing and delivery strategies for phage therapy remain unclear. In a mouse wound infection model, we investigated the impact of dose, frequency, and administration route on the efficacy of phage therapy. We find that topical but not intravenous delivery is effective in this model. High-doses of phage reduces bacterial burden more effectively than low-doses, and repeated dosing achieves the highest eradication rates. Building on these insights, we developed "HydroPhage", a hyaluronan-based hydrogel system that uses dynamic covalent crosslinking to deliver high-titre phages over one week. HydroPhage eradicates infections five times more effectively than intravenous injection. We conclude that hydrogel-based sustained phage delivery enhances the efficacy of phage therapy and offers a practical, well-tolerated option for topical application.

Phage-Based antibacterial hydrogels for bacterial targeting and Ablation: Progress and perspective

The emergence of drug-resistant bacteria makes antibiotics inadequate to treat bacterial infections, which is now a global problem. Phage as a virus with specific recognition ability can effectively kill the bacteria, which is an efficacious antibacterial material to replace antibiotics. Phage-based hydrogels have good biocompatibility and antibacterial effect at the site of infection. Phage hydrogels have remarkable antibacterial effects on targeted bacteria because of their specific targeted bactericidal ability, but there are few reports and reviews on phage hydrogels. This paper discusses the construction method of phage-based antibacterial hydrogels (PAGs), summarizes the advantages related to PAGs and their applications in the direction of wound healing, treating bone bacterial infections, gastrointestinal infection treatment and other application, and finally gives an outlook on the development and research of PAGs.