Sinusitis: Viral, bacterial, or fungal and what is the role of staph?

Recently, it has been recognized that inflammation is the major cause of chronic rhinosinusitis (CRS) rather than bacterial infection. Fungi have emerged as a possible pathogenic agent that drives CRS. One clear-cut group of fungal sinusitis can be divided into invasive and noninvasive. The condition that the allergist is most likely to see is allergic fungal sinusitis. Generally, it appears in atopic, immunocompetent, adolescents and young adults and is marked by the presence of nasal polyps and allergic mucin, which includes eosinophils, Charcot-Leyden crystals, and fungal hyphae. Computer tomographic imaging shows sinus opacification with hyperdense areas. Treatment has been successful with definitive nasosinus surgery and long-term oral prednisone. There is some evidence that fungi also may account for a large percentage of the remaining CRS patients. In this instance, the immune response to common airborne fungi appears to be IgG mediated rather than IgE mediated. Promising therapeutic results have been seen with intranasal antifungal agents but larger multicenter double-blinded placebo-controlled studies are needed. Another unanswered question includes the possible role of staphylococcus-derived enterotoxins in the pathogenesis of CRS.