Honey, Defensin-1 Effective Against Biofilm

Antibiofilm efficacy of honey and bee-derived defensin-1 on multi-species wound biofilm

Published Ahead of Print: 08 February, 2016 Journal of Medical Microbiology doi:

Many clinically relevant biofilms are polymicrobial. Examining the effect of antimicrobials in a multi-species biofilm consortium is of great clinical importance. The goal of this study was to investigate the effect of different honey types against bacterial wound pathogens grown in multi-species biofilm and to test the antibiofilm activity of honey defensin-1 in its recombinant form.

Modified Lubbock chronic wound biofilm formed by four bacterial species (Staphylococcus aureus, Streptococcus agalactiae, Pseudomonas aeruginosa, Enterococcus faecalis) was used for evaluation of honey and recombinant bee-derived defensin-1 antibiofilm efficacy.

Defensin-1 was prepared by heterologous expression in Escherichia coli. We showed that different types of honey (manuka and honeydew) were able to significantly reduced cell viability of wound pathogens (S. aureus, S. agalactiae and P. aeruginosa) in polymicrobial biofilm. None of the tested honeys showed the ability to eradicate E. faecalis in biofilm. In addition, recombinant defensin-1 successfully reduced the viability of S. aureus and P. aeruginosa cells within established polymicrobial biofilm after 24 and 48 hours of treatment. Interestingly, recombinant defensin-1 did not affect the viability of S. agalactiae cells within the biofilm whereas both natural honeys significantly reduced the viable bacteria. Although E. faecalis was highly resistant to defensin-1, defensin-1 significantly affected biofilm formation of E. faecalis and S. agalactiae after 24 hours of treatment, most likely through the inhibiting its extracellular polymeric substances production.

In conclusion, our study reveals that honey and defensin-1 are effective against established multi-species biofilm; however, E. faecalis grown in multi-species biofilm was resistant to both antimicrobials.