Phage therapy combined with Gum Karaya injectable hydrogels for treatment of methicillin-resistant Staphylococcus aureus deep wound infection in a porcine model.

Skin and soft tissue infections (SSTIs) represent a significant healthcare challenge, particularly in the context of increasing antibiotic resistance. This study investigates the efficacy of a novel therapeutic approach combining bacteriophage (phage) therapy with a gum Karaya (GK)-based hydrogel delivery system in a porcine model of deep staphylococcal SSTIs. The study exploits the lytic activity and safety of the Staphylococcus phage 812K1/420 of the Kayvirus genus, which is active against methicillin-resistant Staphylococcus aureus (MRSA). The GK injectable hydrogels and hydrogel films, developed by our research group, serve as effective, non-toxic, and easy-to-apply delivery systems, supporting moist wound healing and re-epithelialization. In the porcine model, the combined treatment showed asynergistic effect, leading to a significant reduction in bacterial load (2.5 log CFU/gram of tissue) within one week. Local signs of inflammation were significantly reduced by day 8, with clear evidence of re-epithelialization and wound contraction. Importantly, no adverse effects of the GK-based delivery system were observed throughout the study. The results highlight the potential of this innovative therapeutic approach to effectively treat deep staphylococcal SSTIs, providing a promising avenue for further research and clinical application in the field of infections caused by antibiotic-resistant bacteria.

Effect of endotoxin on granulation tissue formation in rats.

Open wounds were incised in the dorsal skin of female Wistar rats. Solutions of Salmonella typhosa endotoxin (0.25 micrograms to 25 micrograms/ml saline) were applied 3 times a day on granulation tissue formed in the wounds. 5 days of treatment with the lowest endotoxin concentration resulted in 25% increase of the weight of the tissue, a more than 30% increase of DNA content and a 25% increase of hydroxyproline content in the tissue. Further elevation of these values could be obtained by increasing endotoxin concentration by tenfold or hundredfold but these changes were not very pronounced.

Characterization of bacteriophage S13 suN15 single-strand and replicative-form deoxyribonucleic acid.

The deoxyribonucleic acid (DNA) of bacteriophage S13 was shown to be single-stranded by the criteria of reactivity with formaldehyde, dependence of optical density on ionic strength, broad temperature-absorbance profile, and lack of molar equivalence of the purine and pyrimidine bases. The DNA has a molecular weight of 1.8 x 10(6) daltons, an S degrees (20) of 24.6 in SSC (0.15 m NaCl plus 0.015 m sodium citrate), and a buoyant density of 1.726 g/cc in CsCl. Electron microscopy showed the molecule to be circular. S13 replicative-form DNA was shown to be a double-stranded, circular molecule with a molecular weight of 3.5 x 10(6) daltons, an S([ill]) of 20.7 in SSC, and a buoyant density in CsCl of 1.710 g/cc. The finding that S13 DNA is slightly more pyrimidine-rich than phiX174 DNA but is indistinguishable by all other parameters supports the close genetic relationship between the two bacteriophages.