Direct Antibiotic Delivery Into Soft Tissue Infections Using Ultrasonic Dispersion

Purpose:  Soft tissue infection continues to be a problem in terms of both prevention and treatment, especially with the emergence of Methicillin-resistant Staphylococcus aureus (MRSA).  This study demonstrates a method (Direct Antibiotic Delivery or DAD), to treat bacterial infections by delivering Cefazolin directly into an infection in a concentration high enough to treat MRSA.  

Methodology:  Antibiotic in solution is infused subcutaneously using a blunt cannula followed by external ultrasound using the Mettler ME 800 (9801427).  The ultrasonic energy gently disperses the antibiotic solution into the target tissues by a process of micro-streaming, a process described Weinenger, et al.¹  The presence of fluid in the subcutaneous layer, in addition to a special applicator that contains thousands of piezo electric crystals imbedded in acrylic, allows for a higher power density, which facilitates micro-streaming the infused antibiotic solution gently, deeply and evenly into the target tissues. 

Experience:  In a Phase I IRB study, a vastly higher concentration of Cefazolin was demonstrated in the deep subcutaneous adipose tissue of the operative site using this method as compared to standard intravenous administration of the same dose.  The concentration was demonstrated to be high enough to inhibit even the most virulent forms of MRSA with Cefazolin.  A Phase II IRB study was commenced where patients were treated for severe cellulitis, with follow-up at three months.  As of March 1, 2013, 91 patients have been treated using DAD.  Of these patients, 64% had failed standard IV antibiotic treatment, 29% were diabetic, and 15% required additional treatment.  A few with Pseudomonas required Ceftazidime. 

Results:  The success rate using DAD was 98% with no adverse effects. Below are photographs of a patient who had been unsuccessfully treated for 11 weeks with standard IV treatment.  After one treatment of DAD, her infection was resolved and there was no recurrence.  

            Conclusion:  MRSA is sensitive to Cefazolin at a sufficient concentration.  DAD uses a combination of subcutaneous infusion followed by external high-frequency ultrasonic dispersion to deliver Cefazolin into the target tissues in a sufficient concentration to treat MRSA.  Preliminary clinical cases demonstrate a dramatic resolution of subcutaneous infections.