Background: Chronic Rhinosinusitis (CRS) is the most common chronic disease in the United States. Though for Europe no data are available, we have to assume that the situation is similar. Although the disease is defined very well by clinical symptoms, up to date the etiology and pathogenesis of chronic rhinosinusitis are unknown. CRS is considered to be multifactorial, with thickening of the mucosa and formation of polyps as an end stage of the disease. Treatment of choice includes corticosteroids and/or endoscopic or microscopic surgery. Antibiotics only help, if there is an acute bacterial exacerbation of the disease. They are not able to cure chronic rhinosinusitis per se. In 1999 Mayo Clinic researchers published data concerning the incidence of so-called "allergic" fungal sinusitis (AFS) in their patients suffering from chronic rhinosinusitis, demonstrating the majority of patients investigated presenting those criteria. Our own initial data from 2000 confirmed their findings.
Material and methods: In an open prospective study fungal cultures were obtained from nasal mucus of 238 consecutive patients suffering from CRS. As control group acted 23 members of our staff, who did not show any evidence for CRS. In addition, in 37 CRS patients surgical specimens (mucus and tissue) were investigated histologically for evidence of eosinophilic granulocytes and fungal elements.
Results: Using new techniques for fungal detection in culture and histology as proposed by Mayo Clinic researchers, positive detection of fungal cultures of the mucus of our CRS patients developed from 7 % in the past up to 87 % at present. 91.3 % of our control group yielded a positive result in fungal culture. Histologically, eosinophilic clusters were evident in 94.6 % and fungal elements were detected in 75.5 % within the mucus of 37 surgical CRS patients. Overall, 89.2 % of our surgical patients thus fulfilled the criteria of so-called AFS. Compared to our findings in the past, our latest results show an increase of 80 % in detection of fungal elements in our CRS patients. In all we were able to identify 654 positive fungal cultures in 238 CRS patients and 23 healthy controls respectively. 88 different genera grew, with 2.4 different species per patient and 3.1 different species per healthy control, on average.
Conclusion: Utilizing new techniques of fungal culturing out of the mucus of CRS patients and healthy controls, the number of positive fungal cultures increased dramatically from 7 % to 87 % in our patients and 91.3 % in healthy controls respectively. To obtain these results it is crucial to perform special techniques of mucus sampling and pretreatment for culturing as well as for histological investigations. Our results show, that with suitable techniques fungi can be identified in almost everybody's nose, CRS patient or healthy. When inhaled, those airborne fungi are only "in transit" through the nose. Positive fungal cultures from nasal secretion therefore have to be considered normal findings. The reason for this delayed recognition has to be attributed to our inadequate methods in the past. In contrast to healthy controls, clusters of eosinophils and fungal elements are present simultaneously within the mucus of CRS patients and appear to be a marker of the disease.