If you have ever had a real sinus headache, you know how much trouble a sinus infection can give you. Our sinus cavities are strong defenders of the body, yet are sensitive to many pathogens that may come their way. The sinuses maintain a sterile atmosphere and although we do not fully understand how this occurs, we assume that it is because of the clearing away of mucus, the immune system and possibly antibacterial concentrations of nitric oxide gas in the sinus cavity.(1) Sometimes we might have a sinus infection that accompanies a cold and without even treating the sinus infection, it goes away on its own without our having to seek medical treatment.(2) There are different types of sinusitis that vary according to the cause and location of the infection. These also vary from acute to chronic, mild to severe, and in some cases, even life threatening.

Sinusitis may result from a viral, bacterial, or fungal infection. The most common precursor to sinusitis is a viral upper respiratory tract infection. The development of sinusitis occurs most frequently from some type of obstruction. When an obstruction of any kind occurs, the mucous that contains the pathogens is not removed quickly enough to keep an infection from occurring. Viral infections also increase the amount of mucous in the sinuses, which may cause damage to some of the cells that line the sensitive tissues and thereby increase the time that it takes for the sinuses to clear away excess mucous.

Acute sinusitis can be classified into various categories on the basis of several characteristics including whether it occurs in the hospital or community setting; the immune status of the patient; its infectious or noninfectious cause; and its viral, bacterial, or fungal cause.(1) For example, in a non-hospitalized patient with normal immunity, sinusitis may be viral, bacterial, a combination of both viral and bacterial, or non-invasive fungal. It may also be allergic or non-allergic. In a hospitalized patient, sinusitis is usually bacterial or fungal. Non-infectious causes include allergic or toxic sinusitis. There are several strains of bacteria that are responsible for causing sinus infections. These pathogens have been identified by tests such as direct sinus puncture and aspiration.(3) The most common pathogens seem to be Streptococcus pneumonia, Haemophilus influenzae and Moraxella catarrhalis. Since the use of antibiotics, the risk of complications from a sinus infection occurs less frequently. However, since the type of bacteria causing sinusitis has not changed over the last several decades, there is now an increasing resistance to antibiotics. It is the responsibility of the healthcare professional to determine what type of invading organism is causing the infection, and then to match that with the most effective treatment.

Fungal sinusitis may be either invasive or non-invasive, meaning that it exists separately from the tissue or it has actually penetrated, or invaded the tissue. It is more common to see the non-invasive type which in one form presents itself with a fungus ball (aspergilloma) inside the sinus cavity without invading the surrounding tissue. A second form is seen mainly in patients with asthma and nasal polyposis. It is described as allergic fungal sinusitis and is characterized by extremely thick mucous, but with no evidence of tissue invasion. Invasive fungal sinusitis, on the other hand, can be life threatening.

There are a variety of risk factors associated with sinus infections which can be environmental or physical. Some of the most common environmental risk factors include the inhalation of chemical irritants and cigarette smoke. Besides the common cold and allergies, other physical risks include nasal polyps, deviated septum, and mucous abnormalities such as those that occur in cystic fibrosis. While no