Modelling Staphylococcus aureus biofilms on infected chronic wounds

Chronic wounds, for instance venous, pressure, arterial and diabetic ulcers, are a major health problem throughout the world. Compared with normal wounds, those that take more than four weeks to heal are defined as chronic. Interestingly, the numbers of patients suffering from chronic wounds and the cost for treatment have been increasing during the past two decades. There is increasing evidence that suggests that bacteria infect those chronic wounds and there exist as a biofilm, which affects wound healing and success of treatment. To study biofilms in infected wounds, both in vitro and in vivo biofilm models are important to be developed.

 

In this project, a dynamic ex vivo chronic wound biofilm model for Staphylococcus aureus using a 3D printed chamber and porcine skin was developed. This dynamic model then used to determine antibiotic treatment by using poly(ε‐caprolactone) (PCL) electrospun fibrous mats containing different antibiotics, e.g. tetracycline, gentamicin and fusidic acid. Furthermore, electrospun PCL/silk fibroin scaffolds were also used as carrier of gentamicin. The killing effect of mature S. aureus MRSA 252 growing in the wound model was tested by both viable count and qPCR.

 

The results indicated that this newly designed dynamic model was successful in mimicking single-strain biofilm on infected chronic wounds. Compared with traditional biofilm assays, the flow system generates an air-liquid-solid interface, which more closely approaches to real conditions. Furthermore, results from using electrospun fibrous scaffolds provided strong evidence for their potential in clinical applications to treat infected skin.