Antimicrobial treatment for chronic rhinosinusitis

Abstract

Chronic rhinosinusitis (CRS) is a common and debilitating condition, characterised by persistent inflammation of the sinonasal mucosa. Antibiotics comprise a substantial part of the medical management for CRS, although there is surprisingly little evidence to support their efficacy for this indication. Inappropriate antibiotic treatment encourages the development of resistance and may be detrimental to the sinus microbiota. Accordingly, it is timely to examine the practice of antibiotic therapy for CRS and to explore alternative antimicrobial treatment options. A meta-analysis based on extensive clinical information and bacterial community sequencing data revealed high antibiotic usage in CRS patients with little impact on symptoms or the sinonasal microbiota. High inter-subject variation of the microbiota was observed among all cohorts and differences in microbial diversity were found between CRS and healthy controls but not disease control subjects. An animal model system was established to help improve understanding of the interplay between host inflammatory response, sinus microbiota and medical treatment. The suitability of a unilateral transient sinus occlusion approach to study the microbiota in a rabbit model of sinusitis was demonstrated. Sinonasal inflammation resulted in an increase in bacterial diversity and bilateral inflammatory and microbial changes caused by unilateral intervention were documented. The efficacy and tolerability of an antiseptic solution, neutral electrolysed water (NEW), was evaluated and compared to standard antibiotic treatment in a randomised clinical trial. NEW was well tolerated in the sinus cavities and demonstrated similar clinical and microbiological effects compared to standard antibiotic treatment, suggesting suitability of NEW as a potential alternative to antibiotics. Using an in vitro biofilm model, NEW and povidone-iodine (PVI) were further investigated regarding their activity against mature CRS-associated Staphylococcus aureus biofilms. Both antiseptics showed potent antibacterial effects on planktonic cells. PVI was also effective against biofilms while the antibiofilm activity of NEW was limited. The promising in vitro effects of PVI warrant further clinical investigation. This research helps to clarify the role of antibiotics in the treatment of CRS and the impact that antibiotics have on the sinonasal microbial community. It also presents some data on promising alternative antimicrobial treatment options for the medical management of CRS.