Medical Author : Charles Patrick Davis, MD, PhD
Medical Editor : William C. Shiel Jr., MD, FACP, FACR
Sinus infection facts
- Sinus infections are caused by infections from a pathogenic microorganism (virus, bacterium, or fungus), which grows within a sinus and causes intermittent blockage of the sinus ostium.
- Most people do not transmit sinus infections; most clinicians agree that except for rare instances, sinus infections are not contagious but arise from mainly viruses and bacteria that, by chance, contaminate a person who sinuses support their proliferation because of minor, and rarely, major abnormalities in the person's sinus tissue (for example, swelling, inflammation, abnormal mucus production, and rarely, facial or nasal trauma).
- Sinusitis is inflammation of the air cavities within the passages of the nose. Sinusitis can be caused by infection, but also can be caused by allergies and chemical or particulate irritation of the sinuses.
- Sinusitis may be classified in several ways such as acute sinus infection, subacute sinus infection, chronic sinus infection, infected sinusitis, and noninfectious sinusitis.
- Sinus infection symptoms may include sinus headache, facial tenderness, pressure or pain in the sinuses, fever, cloudy discolored drainage, and feeling of nasal stuffiness, sore throat, and cough, and on rare occasions, associated with facial swelling.
- Bacterial infection of the sinuses is suspected when facial pain, pus-like nasal discharge, and symptoms that persists for longer than a week and are not responding to over-the-counter nasal medications.
- Sinus infection is generally diagnosed based on patient history and physical examination by a health care professional.
- Bacterial sinusitis is usually treated with antibiotic therapy.
- Early treatment of allergic sinusitis may prevent secondary bacterial sinus infections.
- Home remedies for sinus infections include OTC medications such as Tylenol, decongestants, and mucolytics. Nasal irrigation can be accomplished with a Neti-pot or rinse kit (nasal bidet).
- Rare fungal infections of the sinuses (for example, zygomycosis) constitute a medical emergency.
- Complications of a sinus infection that may develop are meningitis, brain abscess, osteomyelitis, and orbital cellulitis.
- There are no fungal vaccines available to prevent fungal sinus infections.
What is a sinus?
A sinus is a hollow, air-filled cavity. For the purposes of this article, a sinus will referred to those hollow cavities that are in the skull and connected to the nasal airway by a narrow hole in the bone (ostium). Normally all are open to the nasal airway through an ostium. Humans have four pair of these cavities each referred to as the:
- frontal sinus (in forehead),
- maxillary sinus (behind cheeks),
- ethmoid sinuses (between the eyes), and
- sphenoid sinus (deep behind the ethmoids).
The four pair of sinuses are often described as a unit and termed the "paranasal sinuses." The cells of the inner lining of each sinus are mucus-secreting cells, epithelial cells and some cells that are part of the immune system (macrophages, lymphocytes, and eosinophils).Functions of the sinuses include humidifying and warming inspired air, insulation of surrounding structures (eyes, nerves), increasing voice resonance, and as buffers against facial trauma. The sinuses decrease the weight of the skull. If the inflammation hinders the clearance of mucous or blocks the natural ostuim, the inflammation may progress into a bacterial infection.
What is a sinus infection?
A sinus infection occurs when a pathogenic microorganism (virus, bacterium, or a fungus) grows within a sinus and causes intermittent blockage of the sinus ostium. Drainage of mucus and pus often occur when the blockage is relieved. The drainage usually goes from the nasal passages to the throat or out the nostrils. Such infections also cause inflammation (an influx of immune cells and swelling of the sinus tissue) of one or more sinuses. This can to block the openings of the sinuses and leads to discomfort.
Inflammation of the air cavities within the passages of the nose (paranasal sinuses) is referred to as sinusitis. Sinusitis can be caused by infection, but can also be caused by allergy and irritation of the sinuses.Sinusitis is one of the more common conditions that can afflict people throughout their lives. Sinusitis commonly occurs when environmental pollens irritate the nasal passages, such as with hay fever. Sinusitis can also result from irritants, such as chemicals or the use and/or abuse of over-the-counter (OTC) nasal sprays, and illegal substances that may be snorted through the nose. About 30 million adults have "sinusitis."
What causes sinus infections?
Sinus infection may be caused by anything that interferes with airflow into the sinuses and the drainage of mucus out of the sinuses. The sinus openings (ostea) may be blocked by swelling of the tissue lining and adjacent nasal passage tissue, for example with common colds, allergies, and tissue irritants such as OTC nasal sprays, cocaine, and cigarette smoke. Sinuses can also become blocked by tumors or growths that are near the sinus openings.
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The drainage of mucous from the sinuses can also be impaired by thickening of the mucous secretions, by decrease in hydration (water content) of the mucous brought on by disease (for example, cystic fibrosis), drying medications (antihistamines), and lack of sufficient humidity in the air. The epithelial cells have small hairlike fibers, called cilia, which move back and forth to help the mucus move out of the sinuses. These small cilia may be damaged by many irritants, especially smoke. This can prevent them from assisting the mucus in draining from the sinuses.
Stagnated mucus provides an environment for bacteria, viruses and in some circumstances (for example, AIDS or immunodepressed persons) fungus to grow within the sinus cavities. In addition, the microbes themselves can initiate and exacerbate sinus blockage. The most commonly infected sinuses are the maxillary and ethmoid sinuses.Rarely, immunodepressed or victims of multiple traumas in disasters such as tsunamis, hurricanes, earthquakes, or tornadoes may breathe in fungi from the soil or water. Eventually, in a few days to over a week, the fungi can grow and cut off blood supply to almost any type of tissue, especially in the nose and eyes. These infections, although rare, are serious and can be deadly and require immediate medical and surgical care. Although the fungal infection may resemble common bacterial sinusitis initially, it is a disease termed zygomycosis or mucormycosis.
What are the types of sinusitis?
Sinusitis may be classified in several ways, based on the time span of the problem (acute, subacute, or chronic) and the type of inflammation (either infectious or noninfectious). The term rhinosinusitis is also used.
- Acute sinus infection (also termed acute sinusitis caused by infection or acute bacterial rhinosinusitis) is usually defined as being of less than 30 days duration.
- Subacute sinus infection as being over 1 month but less than 3 months.
- Chronic sinus infection as being greater than 3 months duration. Chronic sinusitis may be further sub-classified into chronic sinusitis with or without nasal polyps, or allergic fungal sinusitis.
There is no medical consensus on the above time periods.
- Infected sinusitis usually is caused by uncomplicated virus infection. Less frequently, bacterial growth causes sinus infection and fungal sinus infection is very infrequent. Subacute and chronic forms of sinus infection usually are the result of incomplete treatment of an acute sinus infection.
- Noninfectious sinusitis is caused by irritants and allergic conditions and follows the same general time line for acute, subacute and chronic as infectious sinusitis.
What are the signs and symptoms of sinus infection?
Commonly the symptoms of sinus infection are headache, facial tenderness, pressure or pain, and fever. However, some patients may have fever associated with acute sinus infection. Other common symptoms include:
- cloudy, discolored nasal drainage,
- a feeling of nasal stuffiness,
- sore throat, and
Some people notice an increased sensitivity or headache when they lean forward because of the additional pressure placed on the sinuses. Others may experience tooth or ear pain, fatigue, or bad breath. In noninfectious sinusitis, other associated allergy symptoms of itching eyes and sneezing may be common, but may include some of the symptoms listed above for infectious sinusitis. Nasal drainage is usually clear or whitish-colored in people with noninfectious sinusitis.With rare fulminant fungal infections, there may be ulceration, with sharply defined edges and a black, necrotic center in the nasal area. Some fungal infections cause a dark, black-appearing exudates. This requires immediate medical evaluation.
How is sinus infection diagnosed?
Sinus infection is most often diagnosed based on a history and examination made by a doctor. Because plain X-ray studies of the sinuses may be misleading and procedures such as CT and MRI scans, which are much more sensitive in their ability to diagnose sinus infection, are so expensive and not available in most doctors' offices, most cases of sinus infection are initially diagnosed and treated based on clinical findings on examination. These physical findings may include:
- redness and swelling of the nasal passages,
- purulent (pus like) drainage from the nasal passages (the symptom most likely to clinically diagnose a sinus infection),
- tenderness to percussion (tapping) over the cheeks or forehead region of the sinuses, and
- swelling about the eyes and cheeks.
Occasionally, nasal secretions are examined for secreted cells that may help differentiate between infectious and allergic sinusitis. Infectious sinusitis may show specialized cells of infection (polymorphonuclear cells) while allergic sinusitis may show specialized cells of allergy (eosinophils). Physicians prescribe antibiotics if bacterial infection is suspected. Antibiotics are not effective against viral infections; many physicians then treat the symptoms.
If sinus infection fails to respond to the initial treatment prescribed, then more in-depth studies such as CT or MRI scans may be performed. Ultrasound has been used to diagnose sinus infections in pregnant women, but is not as accurate as CT or MRI. Rhinoscopy or endoscopy, a procedure for directly looking in the back of the nasal passages with a small flexible fiber optic tube, may be used to directly look at the sinus openings (ostea) and check for obstruction of these openings by either swelling or growths.
It may sometimes be necessary to perform a needle aspiration (needle puncture) of a sinus to get infected material to culture to determine what pathogen is actually causing the sinus infection. Cultures of the nasal passages are rarely helpful in determining what bacteria or fungus is causing a sinus infection since the nasal passages are often colonized by non-infecting bacteria. The needle puncture procedure is usually done by an otolaryngologist when treatments have failed to alleviate the disease. The procedure requires local anesthesia to minimize any discomfort; some patients require general anesthesia. The sinus is aspirated, the contents sent for culture and staining, and the sinus may be flushed with a saline solution. This is technically the most accurate way to diagnose infectious sinusitis.
In addition, both rigid and flexible endoscopy has been used to obtain diagnostic material from sinuses. These procedures are usually done by an otolaryngologist after topical and local anesthesia. Occasionally, there may be a need to sedate the patient. Some investigators suggest that endoscopy specimens are comparable to those obtained by needle puncture.Fungal infections are usually diagnosed by such biopsy procedures and tissue removed by a surgeon, or by fungal culture and microscopic identification by a microbiologist or pathologist trained to identify fungi. Allergic fungal sinusitis (emphasis on allergic) is an inflammatory response to fungal elements in the sinus cavity and is suspected based on certain CT imaging characteristics and physical exam.
How is sinus infection treated?
For sinusitis caused by virus infection, no antibiotic treatment is required. Frequently recommended treatments include pain and fever medications (such as acetaminophen [Tylenol]), decongestants and mucolytics.
Bacterial infection of the sinuses is suspected when facial pain, nasal discharge resembling pus, and symptoms persist for longer than a week and are not responding to OTC nasal medications. Acute sinus infection from bacteria is usually treated with antibiotic therapy aimed at treating the most common bacteria known to cause sinus infection, since it is unusual to be able to get a reliable culture without aspirating the sinuses.
The five most common bacteria causing sinus infections are Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus, and Streptococcus pyogenes. The antibiotics that are effective treatment for sinus infection must be able to kill these bacterial types. Although amoxicillin (Amoxil) is an acceptable first antibiotic for an uncomplicated acute sinus infection, many physicians choose amoxicillin-clavulanate (Augmentin) as the first-line drug for treatment of a suspected bacterial sinus infection because it is usually effective against most of the species and strains of bacteria that cause the disease.
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How is sinus infection treated? (Part 2)
Taking decongestants (pseudoephedrine) and mucolytics (guaifenesin) orally may be helpful in assisting drainage of sinus infection.
The treatment of chronic forms of sinus infection requires longer courses of medications, such as Augmentin, and may require a sinus drainage procedure. This drainage typically requires a surgical operation to open the blocked sinus under general anesthesia.In general, antihistamines should be avoided unless it is felt that the sinusitis sinus infection is due to allergy, such as from pollens, dander, or other environmental causes.
It is likely that the use of a topical nasal steroid spray will help reduce swelling in the allergic individual without the drying that is caused by using antihistamines although both are occasionally used.Oral steroids may be prescribed to reduce acute inflammation and to help with chronic inflammation in cases with or without polyps and in allergic fungal sinusitis.
In many people, allergic sinusitis develops first, and later, bacterial infection occurs. For these individuals, early treatment of allergic sinusitis may prevent development of secondary bacterial sinusitis.In rare instances or in natural disasters, fungal infections (termed zygomycosis or mucormycosis) may develop in debilitated patients. Death rates of 50%-85% have been reported for patients with these sinus infections. Treatment relies on early diagnosis followed by immediate surgical debridement, antifungal drugs, (mainly Amphotericin B) and stabilizing any underlying health problem such as diabetes.
Are there home remedies for a sinus infection?
Sinus infections caused by viruses can use home (over-the-counter) treatments such as pain and fever medications (acetaminophen [Tylenol]), decongestants, and mucolytics. In addition, some health care providers suggest that nasal irrigation or a sinus rinse solution will help relieve symptoms of sinus infections, even chronic sinusitis symptoms. This irrigation is accomplished with a "Neti-Pot" or a sinus rinse kit (sometimes termed a nasal bidet). The last reference of this article shows a video of a sinus rinse procedure. In 2012, the FDA issued a warning about the use of Neti-Pots; the FDA cautions people not to use untreated tap water for rinsing, as contaminated tap water rinses lead to two deaths.Bacterial and fungal sinus infections usually require antibiotic or antifungal therapy so home treatments without them are often not successful. However, some authors suggest home treatments may reduce symptoms after medical therapy has begun; some health care professionals recommend nasal irrigation after sinus surgery.
What are complications of sinus infection?
Can sinus infection be prevented?
Currently, there are no vaccines designed specifically against infectious sinusitis. However, there are vaccines against viruses (influenza) and bacteria (pneumococci) that may cause some infectious sinusitis. Vaccination against pathogens known to cause infectious sinusitis may indirectly reduce or prevent the chance of getting the disease but there are no specific studies to support this assumption.There are no fungal vaccines against sinusitis.If a person is prone to recurrent bouts of "yearly sinus infection" it may be important to consider allergy testing to see if this is the underlying cause of the recurring problem. Treatment of the allergy may prevent secondary bacterial sinus infections. In addition, sinus infections may be due to other problems such as nasal polyps, tumors or diseases that obstruct normal mucus flow. Treatment of these underlying causes may prevent recurrent sinus infections.
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