International Journal of Medical Device and Adjuvant Treatments (Jul 2021)
Saline nasal spray removal of bacterial biofilms, using a novel in vitro method
Abstract
OBJECTIVE: About 30% of the human population are nasal carriers of Staphylococcus aureus. Although often asymptotic, nasal carriers have an increased risk of infections. Decolonization of nasal S. aureus, by biofilm dispersal has been suggested as an important treatment strategy for reducing infection. Improvement of nasal inflammatory symptoms by saline irrigation is thought to be achieved by biofilm reduction, however the contribution by the dynamic force of the irrigation devices has to our knowledge not been investigated. Preclinical testing of treatments targeting nasal biofilm needs novel in vitro test methodology. This study aimed to develop an in vitro model for nasal bacterial biofilms and, using this model, evaluate the efficacy of saline nasal sprays in removing biofilm by physical force. MATERIALS AND METHODS: S. aureus biofilm was allowed to establish in the presence of mucin on a synthetic membrane placed on nutrient agar. The biofilm-membrane assembly was then placed in the insert of a two-compartment transwell system and treated with nasal spray. The removed biofilm, dislocated to the lower compartment, and biofilm remaining on the membrane, were quantitatively analyzed. Other possible effects on the biofilm were analyzed using a microtiter plate biofilm assay. RESULTS: Treatment with the tested nasal sprays removed the main part of the S. aureus biofilm from the membranes as demonstrated in the in vitro nasal biofilm model. Data from the microtiter plate biofilm assay showed that the nasal spray solution containing plant extracts had higher reducing effect also at static conditions. CONCLUSIONS: This novel method, the Colony biofilm transwell assay, was proven useful for in vitro evaluations of nasal sprays when the effect of physical removal of biofilm needs to be simulated. With this method, we could demonstrate that nasal sprays may have a substantial reducing effect on S. aureus biofilms on a simulated nasal mucosa.
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