A simple animal model of Staphylococcus aureus biofilm in sinusitis

Previous research suggested that the biofilm of Staphylococcus aureus contributes greatly to the recalcitrant nature of chronic rhinosinusitis (CRS). However, the lack of a simple and stable animal model limited further study in this field. The aim of this study was to create a convenient animal model of S. aureus biofilms in the maxillary sinus of rabbit.

New Zealand white rabbits were used as model animals and incised vertically along the median line of the nasal dorsum to expose the anterolateral wall of maxillary sinus, on which a 1.5-mm-diameter hole was drilled to enter the sinus cavity. Through the hole, a piece of gelatin sponge was inserted and then inoculated bacterial suspension into the maxillary sinus. One to 8 weeks after the surgery, the sinus mucosa were harvested and examined with scanning electron microscopy (SEM) and hematoxylin and eosin (H&E) staining.

All rabbits tolerated the surgical procedures and had developed sinusitis by the time they were killed. SEM revealed that biofilms were presented in 100% of rabbits who had bacteria infected for ≥2 weeks, during which the ciliated epithelial cells were encapsulated and gradually destroyed. H&E staining revealed morphological changes of the epithelial cells and infiltration of inflammatory cells in the subepithelial layer, which showed a strong correlation with the results of SEM.

This biofilm model of sinusitis avoids excessive damage to the nasal cavity and sinuses of the rabbits. It may be a desirable animal model for studying the pathogenesis and eradication strategies of bacterial biofilms in sinusitis.