Manuka honey: histological effect on respiratory mucosa

Chronic rhinosinusitis (CRS) is an inflammatory disease in which bacteria are commonly implicated often in the form of a biofilm. Manuka honey has been shown in vitro to be an effective treatment against two common CRS pathogens both in the planktonic and in the biofilm forms. The purpose of this study was to determine if the application of manuka honey to respiratory epithelium would result in histological evidence of epithelial injury.

Using a rabbit animal model, a nonrandomized controlled trial of four treatment regimes was performed with two rabbits in each group. The left nasal cavity was irrigated with a 1.5-mL manuka honey solution once daily and the right nasal cavity was not treated. Groups 1-3 were treated for 3, 7, and 14 consecutive days, respectively, and killed the morning after the last treatment. Group 4 was treated for 14 consecutive days followed by a 14-day washout period and then killed the following morning. The nasal respiratory mucosa was immediately harvested after death. The mucosa was examined by light microscopy for histological change in comparison with the control side.

Cilia were not measured quantitatively but were equally present on the treated and untreated mucosa. There was no histological evidence of inflammation, epithelial injury, or significant morphological changes.

The application of a manuka honey solution to rabbit nasal respiratory mucosa over different treatment intervals did not show evidence of histological epithelial injury.