Preliminary assessment of photoactivated antimicrobial collagen on bioburden in a murine pressure ulcer model.

Abstract

OBJECTIVE AND BACKGROUND DATA:

Overcoming bacterial antibiotic resistance requires alternative strategies. The ability of photoactivated collagen-embedded flavins (PCF) to reduce bioburden in infected pressure ulcers was investigated.

DESIGN AND METHODS:

Two pressure ulcers were created on the dorsum of female BALB/C mice (n=40, 35 g) maintaining a 5 mm skin bridge between lesions. Ulcers and surrounding skin were covered with Tegaderm™ and inoculated with 0.1 mL of 1 × 10(5) colony-forming units (CFU)/mL methicillin-resistant Staphylococcus aureus (MRSA). Fluid was permitted to reabsorb for 10 min. In experiment 1, one wound from each animal was treated using PCF and photoradiation (PCF+R, n=12) or photoradiation alone (R, n=11). Composite dressing-treated wounds received 1 × 1 cm PCF discs. Overlying Tegaderm was excised, and PCF was placed over the wound and again covered with Tegaderm. Wounds were irradiated at 455 ± 5 nm (350 mW, 1 cm spot diameter, 15 min) using a diode laser 10 min after placement. Controls received no PCF or photoradiation (C, n=12). Animals were euthanized 24 h post-therapy. Quantitative bacterial counts (CFU/g tissue) were determined. In experiment 2, composite dressing-treated wounds were irradiated at 455 ± 5 nm (350 mW, 1 cm spot diameter, 15 min) using a diode laser 10 min after daily PCF placement (0, 1, 2, or 3 treatments, n=8/group). Controls received no treatment. Wounds were cultured daily. Animals were euthanized on day 7 post-infection. Quantitative bacterial counts were determined.

RESULTS:

PCF+R significantly reduced bacterial counts at 24 h (experiment 1, p<0.0001; experiment 2, p<0.05). The bacterial counts in rats receiving photoradiation alone were no different from those of untreated controls (experiment 1, p=0.24). PCF+R produced a 2-3 log reduction in bacterial counts (experiment 2, p<0.001). Antibacterial effects increased with number of treatments, and persisted for several days post-therapy (p<0.002).

CONCLUSIONS:

PCF+R inhibited bacterial growth in this model. This effect increased with successive treatments, persisting several days post-therapy. Further studies to optimize this treatment modality are warranted.

• Authors: Raymond J Lanzafame, Istvan Stadler, Ryan Cunningham, Aaron Muhlbauer, Jacob Griggs, Robert Soltz, Barbara A Soltz
• Journal: Photomedicine and laser surgery (Photomed Laser Surg) Vol. 31 Issue 11 Pg. 539-46 (Nov 2013) ISSN: 1557-8550 [Electronic] United States
• PMID: 24138191 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Flavins
• Collagen

Topics

• Animals
• Collagen (pharmacology, radiation effects)
• Colony Count, Microbial
• Female
• Flavins (pharmacology)
• Methicillin-Resistant Staphylococcus aureus
• Mice, Inbred BALB C
• Occlusive Dressings
• Photochemotherapy (methods)
• Pressure Ulcer (microbiology, therapy)
• Staphylococcal Infections (drug therapy)