Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2013

Synergy between Medihoney and Rifampicin against Methicillin-Resistant Staphylococcus aureus (MRSA) (#230)

Michael Liu 1 , Patrick Müller , Jing Lu 1 , Dagmar G Alber 1 , Lynne Turnbull 1 , Ralf C Schlothauer 2 , Dee A Carter 3 , Cynthia B Whitchurch 1 , Elizabeth J Harry 1
  1. The ithree institute, University of Technology Sydney, Sydney, NSW, Australia
  2. Comvita NZ Limited, Te Puke, NewZealand
  3. School of Molecular Bioscience, University of Sydney, Sydney, NSW, Australia

Chronic wounds are a tremendous burden to human health worldwide, currently affecting 2% of the population in developed countries, with significant social and economic costs. Treatment of these wounds is becoming increasingly difficult due to infections caused by antibiotic resistant bacteria such as methicillin-resistant Staphylcoccus aureus (MRSA). Honey is increasingly being used as a topical treatment for these wounds. New Zealand manuka honey has potent broad-spectrum antimicrobial activity, has been shown to inhibit the growth of MRSA strains and resistance to honey has not been attainable in the laboratory1. Using checkerboard microdilution assays, time-kill curve experiments and agar diffusion assays we have shown that combinational use of medicinal manuka honey, Medihoney (Comvita, NZ), and rifampicin, an antibiotic commonly used to treat chronic wounds, is synergistic against MRSA and clinical isolates of S. aureus2. Furthermore, while rifampicin treatment alone readily gave rise to rifampicin-resistant colonies, in the presence of both Medihoney and rifampicin, rifampicin-resistant bacteria could not be isolated.  Our data highlight the potential of a combinational use of Medihoney and common antibiotics to provide more effective treatment of chronic wounds, and also in reducing the risk of antibiotic resistance. We are currently testing for synergistic effects with combinations of Medihoney and other conventional antibiotics that are commonly used for chronic wound treatment. Bacterial biofilms are often found within chronic wounds. These bacterial communities are recalcitrant to antibiotics, and are inherently insensitive to the host immune response, thus making it extremely difficult or impossible to treat. In addition to the antibacterial activity exhibited by Medihoney, we also found this honey can effectively eradicate pre-formed S. aureus biofilms in vitro. Therefore, we are currently investigating whether combinations of Medihoney and antibiotics can act synergistically to increase biofilm eradication efficacy.

  1. Lu J, Carter DA, Turnbull L, Rosendale D, Hedderley D, Stephens J et al. (2013). The effect of New Zealand kanuka, manuka and clover honeys on bacterial growth dynamics and cellular morphology varies according to the species. PLoS One 8: e55898.
  2. Müller P, Alber DG, Turnbull L, Schlothauer RC, Carter DA, Whitchurch CB et al. (2013). Synergism between Medihoney and Rifampicin against Methicillin-Resistant Staphylococcus aureus (MRSA). PLoS One 8: e57679.