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Published on: October 10, 2017
Colistin-loaded silk membranes against wound infection with Pseudomonas aeruginosa
Lars Steinstraesser1, Galina Trust, Andrea Rittig
1Bochum and Munich, Germany From the Department for Plastic Surgery, Burn Center, BG University Hospital Bergmannsheil, Ruhr University Bochum, and the Department of Oral and Maxillofacial Surgery, Klinikum Rechts der Isar, TU Munich.
Background:
Wound infections caused by multidrug-resistant bacteria are a major issue in wound care. An occlusive dressing delivering an antimicrobial agent to the wound may be advantageous. The objective of this study was to evaluate an occlusive silk membrane loaded with colistin to establish an effective antimicrobial wound dressing against Gram-negative bacteria in vitro and in vivo.
Methods:
ST-silk protein membranes (thickness, 100 μm; pore size, <100 nm) were loaded with log-scale colistin dilutions (0.027 to 270 mg/ml) and tested in a modified microbroth dilution assay against Pseudomonas aeruginosa (American Type Culture Collection 27853). A rat burn infection model was used to demonstrate the antimicrobial activity of ST-silk membranes loaded with 270 mg/ml colistin. Finally, a porcine wound infection model was used to study dose response (2.7, 27, and 270 mg/ml colistin loading concentration) in a time-dependent manner (0, 2, 4, and 6 days).
Results:
The in vitro study demonstrated a concentration-dependent antimicrobial effect against P. aeruginosa, with complete elimination at the highest loading concentrations (2.7, 27, and 270 mg/ml). All colistin membranes demonstrated lower colony-forming unit counts compared with the corresponding phosphate-buffered saline or carrier controls. The rat burn infection model demonstrated a colony-forming unit reduction of greater than 3 log-scales for the colistin-loaded ST-silk membranes after 3 days. On average, the wounds' colony-forming unit quantity remained at greater than 1000 during the entire follow-up of 6 days, apart from three wounds where complete bacterial clearance was observed.
Conclusion:
This study demonstrates that occlusive ST-silk membranes loaded with an antimicrobial agent may be an effective dressing for infected wounds.
Insights
This study shows that silk membranes loaded with colistin (an antimicrobial) effectively treat wound infections caused by multidrug-resistant bacteria. The colistin-loaded silk dressing demonstrated significant antimicrobial activity in both lab tests and animal models.
Area of Science:
- Biomaterials Science
- Infectious Diseases
- Wound Care
Background:
- Multidrug-resistant bacterial infections pose a significant challenge in wound care.
- Occlusive dressings offer a potential advantage for delivering antimicrobial agents directly to wounds.
Purpose of the Study:
- To evaluate an occlusive silk membrane loaded with colistin as an effective antimicrobial wound dressing.
- To assess the efficacy of colistin-loaded silk membranes against Gram-negative bacteria in vitro and in vivo.
Main Methods:
- ST-silk protein membranes were loaded with varying concentrations of colistin.
- Antimicrobial activity was tested against Pseudomonas aeruginosa using a modified microbroth dilution assay.
- Efficacy was further evaluated in rat burn and porcine wound infection models.
Main Results:
- In vitro studies showed concentration-dependent antimicrobial effects, with complete elimination of P. aeruginosa at higher colistin loads.
- Colistin-loaded membranes significantly reduced bacterial colony-forming units compared to controls in both rat and porcine models.
- Significant bacterial reduction was observed in animal models, with complete clearance in some wounds.
Conclusions:
- Occlusive ST-silk membranes loaded with colistin demonstrate potential as an effective wound dressing for infected wounds.
- This approach offers a promising strategy for combating multidrug-resistant bacterial infections in wound care.
