The synergistic effect of using bacteriophages and chitosan nanoparticles against pathogenic bacteria as a novel therapeutic approach

An effective antibiofilm strategy based on bacteriophages armed with silver nanoparticles

The emerging antibiotic resistance in pathogenic bacteria is a key problem in modern medicine that has led to a search for novel therapeutic strategies. A potential approach for managing such bacteria involves the use of their natural killers, namely lytic bacteriophages. Another effective method involves the use of metal nanoparticles with antimicrobial properties. However, the use of lytic phages armed with nanoparticles as an effective antimicrobial strategy, particularly with respect to biofilms, remains unexplored. Here, we show that T7 phages armed with silver nanoparticles exhibit greater efficacy in terms of controlling bacterial biofilm, compared with phages or nanoparticles alone. We initially identified a novel silver nanoparticle-binding peptide, then constructed T7 phages that successfully displayed the peptide on the outer surface of the viral head. These recombinant, AgNP-binding phages could effectively eradicate bacterial biofilm, even when used at low concentrations. Additionally, when used at concentrations that could eradicate bacterial biofilm, T7 phages armed with silver nanoparticles were not toxic to eukaryotic cells. Our results show that the novel combination of lytic phages with phage-bound silver nanoparticles is an effective, synergistic and safe strategy for the treatment of bacterial biofilms.

Characterization, antibacterial, and cytotoxic activities of silver nanoparticles using the whole biofilm layer as a macromolecule in biosynthesis

Recently, multi-drug resistant (MDR) bacteria are responsible for a large number of infectious diseases that can be life-threatening. Globally, new approaches are targeted to solve this essential issue. This study aims to discover novel antibiotic alternatives by using the whole components of the biofilm layer as a macromolecule to synthesize silver nanoparticles (AgNPs) as a promising agent against MDR. In particular, the biosynthesized biofilm-AgNPs were characterized using UV-Vis spectroscopy, electron microscopes, Energy Dispersive X-ray (EDX), zeta sizer and potential while their effect on bacterial strains and normal cell lines was identified. Accordingly, biofilm-AgNPs have a lavender-colored solution, spherical shape, with a size range of 20-60 nm. Notably, they have inhibitory effects when used on various bacterial strains with concentrations ranging between 12.5 and 25 µg/mL. In addition, they have an effective synergistic effect when combined with phage ZCSE9 to inhibit and kill Salmonella enterica with a concentration of 3.1 µg/mL. In conclusion, this work presents a novel biosynthesis preparation of AgNPs using biofilm for antibacterial purposes to reduce the possible toxicity by reducing the MICs using phage ZCSE9.

Bacteriophage entrapped chitosan microgel for the treatment of biofilm-mediated polybacterial infection in burn wounds

Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) bacteria are most commonly present in burn wound infections. Multidrug resistance (MDR) and biofilm formation make it difficult to treat these infections. Bacteriophages (BPs) are proven as an effective therapy against MDR as well as biofilm-associated wound infections. In the present work, a naturally inspired bacteriophage cocktail loaded chitosan microparticles-laden topical gel has been developed for the effective treatment of these infections. Bacteriophages against MDR S. aureus (BPSAФ1) and P. aeruginosa (BPPAФ1) were isolated and loaded separately and in combination into the chitosan microparticles (BPSAФ1-CHMPs, BPPAФ1-CHMPs, and MBP-CHMPs), which were later incorporated into the SEPINEO™ P 600 gel (BPSAФ1-CHMPs-gel, BPPAФ1-CHMPs-gel, and MBP-CHMPs-gel). BPs were characterized for their morphology, lytic activity, burst size, and hemocompatibility, and BPs belongs to Caudoviricetes class. Furthermore, BPSAФ1-CHMPs, BPPAФ1-CHMPs, and MBP-CHMPs had an average particle size of 1.19 ± 0.11, 1.42 ± 0.21, and 2.84 ± 0.28 μm, respectively, and expressed promising in vitro antibiofilm eradication potency. The ultrasound and photoacoustic imaging in infected burn wounds demonstrated improved wound healing reduced inflammation and increased oxygen saturation following treatment with BPs formulations. The obtained results suggested that the incorporation of the BPs in the MP-gel protected the BPs, sustained the BPs release, and improved the antibacterial activity.

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

Encapsulation of phages represents a key approach for improving phage stability and controlling phage delivery dosage. The hydrogel made from positively charged quaternized chitosan (QCS) and multivalent crosslinker, aldehyde-modified poly(xylitol sebacate)-co-poly(ethylene glycol) (APP) was introduced for the first time for drug (phage 44AHJD) delivery. The freeze-thawing (FT) treatment enhanced the porous structure and the stress resistance of native hydrogel with increased compression stress (stiffness) from 10 to 20 kPa. The stiffness of the phage-loaded hydrogel (FTP) was suitable for the proper release of phage particles and polymer chains, both working synergistically against bacterial growth. The FTP followed the Korsmeyer-Peppas model's anomalous diffusion of phage particles at different temperatures (30-45 °C) and pH (6.6-8.5) conditions. FTP was sensitive to pH, which released more phage particles at pH-neutral conditions, while the release under acidic and alkaline conditions was more based on gel degradation. The high biocompatibility of FTP hydrogel at its working concentration of 30 mg mL-1 was demonstrated through a hemolysis ratio of <2 %. Sixty percent of the total encapsulated phages and 6 mg mL-1 of hydrogel debris were released after 10 h of hydrogel submerge treatment, which can fight the growing bacteria and the emergence of phage-resistant bacteria.