Is Chronic Rhinosinusitus a Fungal Problem?

Common chronic rhinosinusitis (CRS), which affects 30 million people in the USA alone, could be due to an allergic response to a fungal infection. David Sherris (University of Buffalo, NY, USA) presented his group's latest results at the annual meeting of the American Academy of Allergy, Asthma, and Immunology in San Francisco, USA (Mar 23, 2004). "We first demonstrated that the histopathologic findings of allergic fungal sinusitis (AFS) are present prospectively in 93% of chronic sinusitis cases if they are looked for with sensitive methods. Our subsequent research has confirmed this", comments Sherris.

In a randomised, placebo-controlled, double-blind pilot trial, 24 patients were randomly assigned to receive treatment with intranasal fungicide amphotericin, or a placebo. Computed tomography (CT) scans were recorded at baseline and at 6 months and patients were examined to assess the severity of inflammation using endoscopy at the start of the study, and at 3 and 6 months. The treatment group had a mean 8·8% decrease in inflammatory mucus thickening, while the placebo group had an increase of 2·5%. 70% of patients in the treatment group also showed significant improvement in nasal inflammation, compared with controls.

"We are hoping for multicentre, double-blinded placebo-controlled trials to be the next step towards FDA approval of an antifungal to treat CRS", says Sherris. Alternaria seems to be the most important fungi to elicit the immune response, and a study reporting these results is current awaiting publication. "The results are certainly intriguing", comments Raymond Slavin, professor of molecular microbiology and immunology at the Louis University School of Medicine ( Missouri , USA ) but he warns that they are, as yet, quite controversial. "AFS is considered by most to be a definite entity. It has particular characteristics including a background of allergy with positive skin tests, nasal polyps, a specific CT picture, and production of large mucous plugs containing hyphae", he says. AFS is relatively uncommon but is being increasingly diagnosed. "The claim that a huge number (75-90%) of garden variety chronic rhinosinusitis is also due to fungi seems to be high and I would like to see more data", adds Slavin. Nevertheless, since chronic rhinosinusitis is extremely difficult to treat, Slavin stresses that "any new approach to pathogenesis and treatment would be most welcomed by clinicians".
Kathryn Senior