Obstruction creates a hospitable environment for bacteria, the primary causes of acute sinusitis. Fungi are an uncommon cause of sinusitis, but incidence is increasing. The fungus Aspergillus is the common cause of fungal sinusitis. Others include Curvularia , Bipolaris , Exserohilum , and Mucormycosis. Fungal infections can be very serious and should be suspected in people with sinusitis who also have diabetes, leukemia, AIDS, or other conditions that impair the immune systems.
Fungal infections can also occur in patients with healthy immune systems.
There have been a few reports of fungal sinusitis caused by Metarrhizium anisopliae, which is used in biological insect control. Causes of Chronic or Recurrent Acute Sinusitis Chronic or recurrent acute sinusitis can be a lifelong condition and may result from untreated acute sinusitis that causes damage to the mucous membranes, medical disorders that cause chronic thickened stagnant mucus, or structural abnormalities. The same organisms that cause acute sinusitis are often present in chronic sinusitis. Fungi can also cause chronic and recurrent sinusitis. An uncommon form of chronic and highly recurrent sinusitis is caused by an allergic reaction to fungi, usually, aspergillus , growing in the sinus cavities.