Respiratory Tract Infections; Causes, Symptoms, Treatment

Causes and Risk Factors

URIs can be caused by both viruses and bacteria. There are several sub-types within each of these categories. For viruses, these include:

• Rhinovirus
• Adenovirus
• Coxsackie virus
• Parainfluenza virus
• Respiratory syncytial virus
• Hyman metapneumovirus

For bacteria, these include

• Group A beta-hemolytic streptococci (GABHS)
• Corynebacterium diphtheriae (diphtheria)
• Neisseria gonorrhoeae (gonorrhea)
• Chlamydia pneumoniae (chlamydia)
• Group C beta-hemolytic streptococci

Other Causes

Typical Bacterial Infections

• Haemophilus influenzae
• Staphylococcus aureus
• Klebsiella pneumonia

Atypical Bacterial Infections

• Legionella pneumophila
• Mycoplasma pneumoniae
• Chlamydophila pneumoniae
• Chlamydia psittaci

Parasitic infections

• Respiratory cryptosporidiosis

Viral infections

• Adenovirus
• Influenza A virus
• Influenza B virus
• Human parainfluenza viruses
• Human respiratory syncytial virus
• SARS coronavirus
• Middle East respiratory syndrome coronavirus
• Aspiration pneumonia

Several actions, events or conditions can increase the risk of a URI, including

• When someone sick sneezes or coughs without covering their nose and mouth. This causes droplets containing viruses to be sprayed into the air.
• Closed areas or crowded conditions, such as hospitals, institutions, schools and daycare centers.
• When you touch your nose or your eyes—infection occurs when secretion touches the nose or eyes.
• During fall and winter (September to March) while people are more likely to be inside.
• When humidity is low—indoor heating promotes the survival of many viruses that lead to URIs.
• If you have a weakened immune system.
• Chronic respiratory disease
• Chronic renal disease
• Chronic liver disease
• Diabetes
• Serious central nervous system diseases (cerebral vascular accident, transient ischaemic attack, Parkinson’s disease, dementia, and multiple sclerosis)
• Rheumatoid arthritis
• Cancer
• Osteoporosis

Symptoms

Symptoms of a URI may include

• Runny nose, nasal congestion, sneezing, cough and sputum production (these are considered the most common symptoms)
• Fever
• Fatigue
• A headache
• Pain during swallowing
• Wheezing
• congestion, either in the nasal sinuses or lungs
• a runny nose
• a cough
• a sore throat
• body aches
• fatigue
• a fever over 103˚ F (39˚ C) and chills
• difficulty breathing
• dizziness
• loss of consciousness

Acute upper respiratory tract infections include rhinitis, pharyngitis, tonsillitis, and laryngitis. Symptoms of URTIs commonly include

• Cough
• Sore throat
• Runny nose
• Nasal congestion
• Headache
• Low-grade fever
• Facial pressure
• Sneezing
• Malaise
• Myalgias

The onset of symptoms usually begins one to three days after exposure and lasts 7–10 days, and can persist up to 3 weeks.

Diagnosis 

If your child has a complicated respiratory infection, the doctor may perform one or more of these tests:

• Blood tests. These tests are performed to see if bacteria are in the blood.
• Imaging tests. A chest X-ray or computed tomography (CT) scan may be performed to check for infections in the chest, lungs, orbits or sinuses.
• Throat or nasal swab. This test takes a sample of cells and mucus from the nose, throat or tonsils to find the cause of the infection.

Differential Diagnosis

• Common Cold
• Allergic rhinitis
• Sinusitis
• Tracheobronchitis
• Pneumonia
• Influenza
• Atypical Pneumonia
• Pertussis
• Epiglottitis
• Streptococcal Pharyngitis/Tonsillitis
• Infectious Mononucleosis

Treatment

In most cases, people with URIs know what they have and are visiting the doctor to find symptom relief. Most diagnoses can be made using medical history and a physical exam. If needed, tests like throat swabs, X-rays or CT scans might be used for a diagnosis.

URI treatments include:

• Cough suppressants
• Expectorants
• Vitamin C or zinc
• Nasal decongestants
• Steam inhalation and gargling with salt water
• Analgesics like acetaminophen and NSAIDs can help with fever, aches and pains
• Treatment of the symptoms of upper respiratory infection is usually continued until the infection has resolved.

The 2008 National Institute for Clinical Excellence (NICE) guidelines recommend no antibiotics or delayed antibiotics for most patients with RTI .^[rx]

Treatment

Amoxicillin 500 mg (children: 15mg/kg; maximum 500mg) orally every 8 hours for 5 days

or

doxycycline 100 mg (children >8 years: 2mg/kg; maximum 100 mg) orally every 12 hours for 5 days (contraindicated during pregnancy)

or

sulfamethoxazole 800mg + trimethoprim 160mg (children: 20mg/kg + 4mg/kg; maximum 800mg + 160 mg) orally every 12 hours for 5 days.

Cefalosporins and fluoroquinolones are not recommended for bronchitis.

Acute exacerbations of chronic bronchitis

Acute exacerbations of chronic bronchitis are often due to viral infection and do not require treatment with antimicrobials. Antimicrobial treatment should, however, be considered in patients with increasing cough, dyspnoea and increased production and purulence of sputum. The most common causative organisms are H. influenzae, Moraxella catarrhalis and S. pneumoniae.

Doses refer to adults, as this condition is rarely found in children.

Amoxicillin 500 mg orally every 8 hours for 5 days

or

amoxicillin 500mg + clavulanic acid orally every 8 hours for 5 days

or

sulfamethoxazole 800mg + trimethoprim 160 mg orally every 12 – 24 hours for 5 days.

Chronic purulent bronchial infection and chronic airway disease are predominantly diseases of adults. Chronic suppurative lung disease in children (e.g. bronchiectasis) may occasionally require treatment with amoxicillin (30mg/kg (maximum 1g) orally every 8 hours for 5 days) or chloramphenicol (25mg/kg (maximum 1g) i.v. or i.m. every 6 hours for 5 days). Cystic fibrosis infections require specialist clinical management and laboratory services.

• Acetaminophen –  Read all cold medicine package labels. Do not take more than one drug that contains acetaminophen. Taking too much acetaminophen can damage your liver. Acetaminophen doses should not exceed 4 grams per day. Individuals with liver damage or liver problems should not exceed 2 grams of acetaminophen per day.
• Antibiotics – are sometimes used to treat upper respiratory infections if a bacterial infection is suspected or diagnosed. These conditions may include strep throat, bacterial sinusitis, or epiglottitis. Antivirals may occasionally be recommended by doctors in patients who are immunocompromised (poor immune system). The treating doctor can determine which antibiotic would be the best option for a particular infection.
• Nonsteroidal anti-inflammatory drugs  – such as ibuprofen (Motrin, Advil) can be used for body aches and fever.
• Antihistamines –  such as diphenhydramine (Benadryl) are helpful in decreasing nasal secretions and congestions.
• Nasal ipratropium  – (topical) can be used to diminish nasal secretions.
• Cough medications – (antitussives) can be used to reduce a cough. Many cough medications are commercially available such as dextromethorphan, guaifenesin (Robitussin), and codeine all have shown benefits in reducing cough in upper respiratory infections.
• Target likely organisms with first-line drugs – Amoxicillin, Amoxicillin/Clavulanate
• Use shortest effective course – Should see improvement in 2–3 days. Continue treatment for 7 days after symptoms improve or resolve (usually a 10–14-day course).
• Honey – can be used in reducing cough.
• Steroids  – such as dexamethasone  and prednisone orally  are sometimes used to reduce inflammation of the airway passage and decrease swelling and congestion.
• Decongestants – such as pseudoephedrine oral, phenylephrine  can be used to reduce nasal congestion (generally not recommended in children less than 2 years of age and not recommended for individuals with high blood pressure).
• Oxymetazoline –  nasal solution is a decongestant, but should only be used for short-term.
• Combination medications containing many of these components are also widely available over the counter.

To ease the discomfort from specific cold and flu symptoms, consider using the following types of OTC medicines

• To reduce fever and pain — analgesics- Acetaminophen is generally preferred. Ibuprofen or naproxen is also commonly used. Aspirin should be avoided due to its risk of developing Reye’s syndrome. (Reye’s syndrome is a condition that affects all body organs and is most harmful to the brain and liver.)
• To dry out the nose — antihistamines –  Try an antihistamine, such as diphenhydramine. Because these products can make you sleepy, avoid driving and other complex tasks while taking these medicines. Loratadine available is a non-drowsy alternative, but may not be as effective as other antihistamines for reducing cold and flu symptoms.
• To relieve a stuffy, clogged nose — decongestants  – Try an oral decongestant, such as pseudoephedrine. However, insomnia, nervousness, and irritability can occur when taking these drugs. Those who are pregnant or have uncontrolled high blood pressure should avoid pseudoephedrine products. Often decongestants are combined with other drugs (especially antihistamines) in OTC medicines. A “-D” at the end of a medicine’s name means it includes an oral decongestant.
• To relieve a runny nose or sinus pressure — nasal steroids- Medications like fluticasone available without a prescription) or mometasone; prescription needed) can relieve symptoms. These medicines are also used for seasonal allergies. These are not the same as  or other OTC nasal preparations. Antihistamines will also help.
• To make blowing your nose easier or loosening cough/mucus production — expectorants: Try guaifenesin . These products help thin the thick, discolored drainage coming out of the nose and mouth.
• To reduce coughing — antitussives –  Dextromethorphan can help suppress cough.
• To relieve a sore throat – Try throat lozenges or gargle with warm salt water a few times a day. Analgesics are also helpful.
• Oral zinc supplementation – has been used in recent years to shorten the duration and reduce the severity of symptoms of upper respiratory infection and common cold. This therapy has been studied in children with upper respiratory infection and the results are mixed. The FDA has not approved the use of oral zinc to treat the common cold or upper respiratory infections. There are reports of nausea and unpleasant taste caused by oral zinc.
• Topical nasal zinc products  – has been also used to attenuate the symptoms of upper respiratory infection. Some studies suggest loss of the sense of smell associated with the use of this over the counter product.
• The use of oral vitamin C – is thought to shorten the duration of upper respiratory infection symptoms, but research data are inconclusive regarding the benefits of vitamin C.

Complications of a Respiratory Infection may include

• Empyema – Empyema is a collection of pus beside the lungs, caused by a bacterial infection that can lead to life-threatening problems such as sepsis (bacteria in the blood) and shock. Symptoms include fever, cough, shortness of breath and chest pain.
• Lung abscess – A lung abscess is a pus-filled cavity in the lung surrounded by inflamed tissue. It is usually caused by a severe infection such as pneumonia or tuberculosis or from inhaling material into the lungs from the mouth.
• Potts puffy tumor – This is an uncommon complication of sinusitis (a type of upper respiratory tract infection that causes inflammation of the sinus cavities in the skull). It is an abscess of the forehead area with frontal swelling. Potts puffy tumor is usually seen in late childhood or adolescence. Symptoms include red, tender swelling in the mid-forehead, headache and fever.
• Orbital cellulitis – Orbital cellulitis is another possible complication of sinusitis. This is an infection of the tissue within the eye socket and around the eye. Symptoms include pain, swelling, red eye, fever, a bulging eye, impaired vision and impaired eye movements.
• Orbital abscess = Also a further complication of sinusitis causing orbital cellulitis, orbital abscess is a collection of bacteria and pus behind the eye. Symptoms include eye pain, bulging of the eye, redness of the eye, changes in vision and fever.
• Mastoiditis – Mastoiditis is a complication of otitis (a type of upper respiratory tract infection that causes inflammation and possible infection of the middle ear). This is a serious bacterial infection that affects the mastoid bone behind the ear. Symptoms may include ear pain, fever, headache, drainage from the infected ear, redness, swelling and tenderness in the affected ear.dentifying patients at risk of poor prognosis for developing pneumonia^[rx]

References