Study Title: ION-ZC1 Antimicrobial Study 3 - MRSA in Biofilm

Author: INDEVION Biotechnology Research and Development Ltd. Principal Investigator Dr. Zsolt Keresztessy, Ph.D. (2017).

Methods: ION-ZC1 antimicrobial study report 3 evaluating MRSA in biofilm assays using the microtiter plate sensitivity method. The study design will provide information on MRSA under biofilm conditions. The anti-biofilm activity of ION-ZC1 was evaluated by the crystal violet assay published by O'Toole (2011). The study was conducted against three methicillin-resistant Staphylococcus aureus isolates.

Results: Minimum inhibitory concentrations (MIC) were determined after 24 hours in which a prominent decrease (50%) of the biofilm mass was observed. Isolates of Staphylococcus aureus (MRSA). The degree of inhibition of biofilm mass at 6.5%, 12.5%, 25% and 50% ION-ZC1 in Staphylococcus aureus isolates 22953, 22580 and 21795 were in the range of 5% (v/v) to 38% (v/v), averaging each of the three groups isolated provides a CIM value of inhibition at each concentration of 5%, 11%, 14% and 29% (v/v) in vitro.

Conclusions: On average at least 50% inhibition was detected on biofilm reduction in 24 hours. Future studies over a longer period of time may determine increased MRSA inhibition in biofilm as shown in the positive results of Study 2 (MRSA in non-biofilm conditions). ION-ZC1 shows promising in vitro results in a wide range of gram-negative and gram-positive bacteria and multiple species of fungi. ION-ZC1 in vitro can reduce biofilm mass and cause MRSA cell death.