The Effectiveness of Topical Silver Colloid in Treating Patients With Recalcitrant Chronic Rhinosinusitis

The paranasal sinuses are within the bones of the face and head. Six paired sinuses are present in humans, and although their exact function is a topic for debate, they appear to play several roles ranging from cushioning the brain during trauma to increasing resonance of the voice and releasing nitric oxide to help with lung physiology. The sinuses are lined with a layer of respiratory epithelium that normally secretes a small amount of mucus to keep the sinuses lubricated and contains cilia to help sweep away debris. Rhinosinusitis occurs when this lining gets infected or irritated which can lead to excessive mucus production and impaired mucus drainage. It is a very prevalent condition affecting up to 16% of the population and is the fifth most common diagnosis generating an antibiotic prescription1,2.

Chronic rhinosinusitis without polyposis (CRSsP) is characterized by persistent symptoms of nasal congestion, mucus discharge from the nose, facial pain or anosmia for at least three months. Unlike acute rhinosinusitis, which is usually caused by infection, CRSsP can have more elusive causes and can be profoundly more complicated.3 Due to the challenging nature of CRS, physicians often use a variety of treatment strategies against it.3 Potential treatments for CRSsP include lifestyle modifications (quitting smoking, reduce allergen exposure, etc.), nasal saline irrigations, nasal corticosteroid spray or irrigations, antibiotics and surgery. Typically, there is a stepwise fashion to the therapy offered to patients whereby the more aggressive or invasive modalities are reserved for those who did not benefit from simpler approaches. Even despite all these regimens there is a small subset of patients who continue to fare poorly. One thought toward the reason for this centers on the frequent presence of biofilms within the sinuses of recalcitrant CRSsP patients.4

Biofilms have been reported in CRS populations for a decade now by a number of authors.4,5 Furthermore, their presence has been linked to more severe disease both pre and post-operatively. Using fluorescence in situ hybridization investigators have been able to identify staphylococcus aureus (S. aureus) and Haemophilus influenza (H. influenza) as the most common biofilm-forming organisms.5 In fact, H. influenza biofilms seem to be more common in milder patterns of CRS, whereas S. aureus biofilms are present in more severe, refractory forms of the disease.5 A very recently published study demonstrated colloidal silver directly attenuating S. aureus biofilms in vitro and herein lays the premise of our study.6

Interest in colloidal silver, a commercially available naturopathic product, was sparked after clinical improvements were seen in a number of recalcitrant CRS patients who sprayed the agent intranasally. Silver has long been used for its bactericidal properties, as it is one of the most toxic elements to microorganisms.7 Silver-impregnated dressings and catheters are currently used in the treatment of burns, ulcers and chronic wounds. Clear advantages of silver over modern antibiotics include broad spectrum activity against Gram-positive and Gram-negative organisms, fungi, protozoa and some viruses as well as the general absence of resistance developing in a number of bacterial species.7,8 In addition, silver has been shown to have activity against Pseudomonas aeruginosa biofilm development.9

The main reasons colloidal silver fell out of use as an antiseptic are due in large part to the advent of antibiotics, uncertain safety, and the production of argyria on ingestion10. Although it is not yet known which dose of silver is required to cause argyria, all case reports to date are following excessive daily consumption of the element over a period of years10,11. Topical application of silver has been reported to cause localized argyria whereas systemic toxicity is generally the result of longstanding oral intake12. Argyria is more or less a benign condition characterized by a slate-grey metallic appearance of the skin. Apart from skin discoloration, extreme cases of systemic silver toxicity can be associated with thrombocytopenia, abnormal clotting, renal impairment, proteinuria, and neurological symptoms such as seizures, loss of coordination and sensory loss12. All of these possible side effects are exceedingly rare and are not expected to be an issue in this study. There is, however, a possibility that there might be localized pigmentation of the nasal mucosa, of which there are no significant consequences13.

Our goal with this project is to test whether topical silver colloid is a feasible treatment option for patients with refractory CRS. With the recent publication of a proof of mechanism study6, the investigators are looking to extend the same notion into a proof of concept investigation. The investigators propose taking twenty volunteer patients with recalcitrant CRS and trial randomized to a course of daily intranasal silver colloid for 6 weeks followed by saline, or vice versa. Pre and post-treatment measurements will be taken using validated scoring systems for CRS patients14-16. These include the Sino-Nasal Outcome Test (SNOT-22)14, Lund-Kennedy score15 and the Smell Identification Test16, which examine quality of life indices, endoscopic assessments and sense of smell, respectively. Should the results of this preliminary study be in favor of silver colloid use in CRS patients the investigator should look into arranging a formal Randomized-Controlled Clinical Trial.