Corticosteroids and the Sinonasal Microbime

Abstract

Chronic rhinosinusitis (CRS), a disease of multifactorial aetiology characterised by the presence of infection and inflammation. The initial triggering factor/s and the perpetuating factor/s in the disease progression of CRS remains a matter of much debate. As a result of this, the treatment modalities in CRS is directed against infections using antibiotics and against inflammation using oral and topical steroids. Quiet often these therapies are given alone or in combinations for varying duration and frequency to bring clinical improvement in patients. The most unfortunate outcome is the chronicity of this disease despite multiple courses of medical therapies and in many cases, sinus surgeries. With the emergence of concepts of the microbiome and its implications in health and disease, and many chronic diseases linked to specific microbial alterations, the CRS microbiome have been extensively studied. This has led to the understanding that microbial richness and abundance are very individual specific and there are probably no clear demarcations between a healthy and a diseased sinus. However, a microbial dysbiosis could be associated with an inclination towards unhealthy state. Although antibiotics have been used to effectively to control a number of infections, their irrational use have led to the emergence of multidrug resistant organisms as well as microbial dysbiosis in humans with a potential to develop diseases. CRS is the number one reported condition for which antibiotics are prescribed at the peripheral general practice. Despite providing excellent clinical outcomes, corticosteroids are often combined with or are replaced by antibiotics in the treatment of CRS. This thesis, attempted to see if corticosteroids in addition to its anti-inflammatory property, had an effect on bacterial growth. We also investigated the usefulness and efficacy of antibiotics over corticosteroid therapy to determine if antibiotics are warranted as first line therapy in the medical management of CRS. Towards this, the aims of the study were: 7 1. To look at the potential antibacterial action of corticosteroid and the different excipients in a commercial preparation of topical nasal steroid in vitro. 2. To investigate the growth and metabolic response of a common CRS pathogen, Staphylococcus aureus in the presence of different concentration of corticosteroid. 3. Finally, to conduct a double-blinded, randomised placebo-controlled trial to better understand the usefulness and efficacy of corticosteroid and antibiotic therapies in CRS along with the probable microbiome changes they bring about and its influence on the clinical outcomes in these patients.