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Samer Al-Khudari
Jay M. Dutton, MD
Americans suffer from over one billion upper respiratory infections every year and each and every one of us has been affected by them at some point in our lives. The respiratory tract is the pathway air travels through the body to reach the lungs. Anatomically, it is divided into the upper and lower airways. The upper tract begins at the nose, and includes the sinuses, pharynx, and larynx. This leads to the trachea, bronchi, and pulmonary alveolar spaces, collectively know as the lower respiratory tract. While the term Upper Respiratory Infection (URI) may refer to any infection of this pathway caused by viruses, bacteria, or fungi it is commonly referred to as the "common cold".
The majority of URI's occur during the cold and rainy months. In the United States, URI's are the most common reason people miss school and work. They are also one of the most common reasons patients seek medical attention. The symptoms and durations of URI's are quite varied but they may provide a clue as to the specific cause. Certain causes may require no specific treatment other then symptomatic control, although at time targeted therapy may be indicated to hasten recovery and help avoid complications. More information is provided on three types of infections below.
Viral URI
The most common cause of a URI is an underlying viral infection. The predominating symptoms are runny nose, nasal congestion, and sneezing. Other common symptoms include cough, nasal discharge, fatigue, headache, fever, decreased smell, muscles aches, ear fullness, and itchy eyes. While there are over 200 viruses that may cause a URI, the majority are due to one of the following: rhinovirus, parainfluenza virus, coronavirus, respiratory syncytial virus, coxsackievirus, and influenza virus.
The average viral URI lasts approximately 7-10 days and most symptoms begin to improve within one week, although symptoms may linger for several weeks. Treatment of a viral URI primarily involves managing the symptoms and allowing the infection to run its natural course. Treatment most commonly includes decongestants, fever reducers, rest, and maintenance of good oral hydration. Laboratory testing and imaging are not typically necessary as they will not affect the treatment. In certain patients with chronic illness or organ transplants, testing may be indicated. Most viral infections are transferred from person to person through direct contact, so it is always important to practice good hygiene especially hand washing to help prevent the spread of disease.
If a URI lasts longer then 7-10 days and shows very little improvement, it is important to seek medical attention as there may be an infection of a different etiology. Although it can be difficult to differentiate causes, the timing of a patient's symptoms and quality and color of the nasal discharge can be helpful to differentiate the cause of the URI. Watery and light colored mucus discharge is suggestive of a viral URI. Thick and dark colored mucus may be suggestive of a more serious underlying process.
Bacterial Sinusitis
Sinusitis refers to the inflammation/infection of one or more paranasal sinuses and usually is associated with impaired drainage from the sinuses. Sinusitis is subdivided into acute (symptoms lasting <4 weeks), subacute (symptoms lasting 4 weeks to 3 months), and chronic (symptoms lasting >3 months). In adults, approximately 10% of URI's may be caused by bacterial sinusitis, while in children the number is slightly lower. In children younger than 1 year of age, sinusitis is rare as the sinuses are still developing.
The most common symptoms of bacterial sinusitis are facial pain, congestion, headache, nasal drainage, dental pain, and ear fullness. While it is difficult at times to differentiate bacterial sinusitis from a viral URI, it is important as bacterial sinusitis will require therapy with antibiotics. When properly treated, sinusitis is rarely complicated, but due to the vital location of the sinuses serious consequences can occur. Complications include but are not limited to disease extension into the orbit, facial cellulitis, meningitis, brain abscess, and osteomyelitis (infection of the bone).
Adult acute bacterial infections of the sinuses are usually due to Haemophillus influenza and Streptococcus pneumoniae. Pediatric bacterial sinusitis is due to the same organisms with the addition of a third organism, Moraxella catarrhalis. Further evaluation with nasal endoscopy or imaging studies such as CT may be necessary for more refractory or chronic infections. The primary treatment for bacterial sinusitis is oral antibiotics, often combined with adjunctive therapy such as decongestants, nasal steroids, saline irrigations. Surgery is typically reserved for chronic or recurrent infections refractory to maximal medical management.
Fungal Sinusitis
Fungal sinusitis is an infection/inflammation of the sinuses due to a fungus. Four major types of sinus infection are thought to be due to fungus: acute and chronic invasive sinusitis, fungus ball, and allergic fungal sinusitis. In the past, fungal sinus infections were considered rare and were most likely to occur only in immunocompromised patients. Recently, there is new evidence that shows they may actually be more common than once thought. Also, recent evidence suggests that the body's immune response to some fungi may be an important cause of chronic sinus infections.
Fungus ball is an infection most commonly due to an overgrowth of Aspergillus and most commonly occurs in the maxillary sinus. This fungus ball may cause recurrent sinus infections ranging in severity of symptoms. Treatment is aimed at surgically removing the mass. Acute and chronic invasive sinusitis are the most serious, yet least common of the fungal infections. These infections can rapidly advance to the vital structures near the sinuses. While the acute form is most commonly seen in immunocompromised patients or poorly controlled diabetics, the chronic form can be seen in otherwise healthy patients. Treatment is usually through a combined approach of medication and surgery. Allergic fungal sinusitis is thought to be due to more commonly encountered environmental fungi. Symptoms are similar to other infections of the sinuses, although its prevalence is debated. Treatment is usually a combination of anti-inflammatory and antifungal agents.
Overall, fungal infections of the sinus cause similar symptoms to that of bacterial sinusitis. It may be difficult to identify the fungus based upon the history and symptoms alone. Research regarding the role fungi play in chronic infections is ongoing and this may lead to new treatment modalities in the near future. It is clear that acute invasive fungal infections are serious and may necessitate complicated medical treatment and surgery.
Table 1. Summary of Viral URI and Bacterial Sinusitis
| Viral URI | Bacterial Sinusitis |
| Duration of Symptoms | Usually resolve within 7-10 days | Without treatment greater then 10 days |
| Nasal Discharge | Watery, clear, and yellow | Thick, dark, and purulent |
| Most common Organisms | Rhinovirus, Parainfluenza virus, Coronavirus | Hemophillus influenza and Streptcoccus pneumoniae |
| Usual Treatment | Decongestants, Fever Reducer, Rest, Oral Hydration | Antibiotics, Decongestants Hydration Surgical Drainage or Sinus Surgery* |
| Chronic State | No Chronic state | Can Be acute, subacute, and chronic |
| Complications | Usually none | Orbital infections, facial cellulites, meningitis, brain abscess |
*Surgical Treatment most commonly used in chronic cases
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