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Facts About Pneumonia

Pneumonia is caused by an infection or injury to the lower respiratory tract resulting in inflammation. Infectious agents or injury caused by aspiration of dust or chemical agents causes fluid to enter the alveolar spaces. The symptoms of pneumonia include chills, fever, cough, chest pain, laboured breathing, fatigue, anorexia, headache, leucocytosis, and bloody sputum. Pneumonia can also result from the aspiration of gastric contents, water, or other irritants.

Infectious pneumonia is common in the US with about 2-3 million cases being diagnosed each year resulting in 40,000 to 70,000 deaths. Mortality is estimated at 14% for patients requiring hospitalisation. Risk factors include upper respiratory infections, advanced age, alcoholism, cigarette smoking, institutionalisation, malnutrition, immune system compromise, and illnesses such as cancer, liver or kidney disease, congestive heart disease, and cerebrovascular disease. Pulmonary defence mechanisms such as the cough reflex, mucocilliary action, and immune responses, normally prevent infections but pneumonia results when the pathogen gets past these mechanisms. Virulence and severity of the pneumonia depends on the health of the individual, the particular microorganism, and the size of the inoculation.

Respiratory support, if needed, and antibiotics are the treatments of choice for most infectious pneumonias. Rarely antiviral drugs are used.

Bacterial Pneumonia
Pneumonia in adults is most commonly caused by bacterial agents. It is a frequent respiratory infection in industrialized cities, lower socio-economic groups or in cases of crowded living quarters. The incidence of bacterial pneumonia increases in winter and spring in temperate zones.
Most infectious pneumonia is caused by bacteria and 60-80% of all bacterial pneumonia is caused by Streptococcus pneumoniae. These organisms are routinely found in the upper respiratory tract of healthy persons. It is when they are drawn into the lower respiratory tract of susceptible individuals that they cause infection. Pneumococci are spread by droplets or direct contact with an infected person. Bacterial pneumonia has an incubation period of 1-3 days. Antibiotic therapy with penicillin or erythromycin makes the patient non-infective and generally results in a rapid recovery.

A vaccination that confers 90% protection is available and recommended for those (except infants less than 2 years old) at highest risk of fatal infection. Vaccination of people older than age 65 is recommended with a booster every 6 years thereafter. The influenza vaccine is recommended at yearly intervals and can be administered at the same time as the pneumococcal vaccine.

Mycoplasma pneumoniae causes pneumonia, particularly in older children and young adults, of gradual onset that lasts for a few days to weeks. The symptoms of this type of pneumonia are headache, malaise, sore throat, cough, and leucocytosis. Diagnosis is by finding antibodies in the blood. Infection occurs 14-21 days after droplet inhalation or direct contact with an infected individual. Antibiotic treatment with tetracycline or erythromycin is effective. Penicillin is completely ineffective because mycoplasmas do not have cell walls, which this antibiotic targets.
Chlamydia trachomatis is a sexually transmitted disease that may also cause pneumonia and bronchitis. It usually is a subacute infection of early infancy producing a sudden cough and eosinophilia without fever that lasts from 1-3 weeks, but it may occur in adults too. It is transmitted to infants at birth from the cervix of an infected mother. Adults having chlamydial pneumonia are usually immune compromised, with the infection spreading from the eye (conjunctival) to the respiratory tract via the nasolacrimal duct. Diagnosis is by isolation of the organism and by finding antibodies in the blood. Erythromycin and tetracycline are effective therapies.

Eukaryotic Pneumonia
Pneumocystis carinii is an organism of mixed fungal and protozoal character that causes an acute, often fatal, respiratory infection in infants or immune compromised patients. Symptoms are laboured or difficult breathing, cyanosis and heavy infiltrates in the alveolar spaces. Diagnosis is by finding the organism in mucous smears or by biopsy of lung tissue. Treatment is by the use of trimethoprim-sulfanethoxazole or pentamidine isothionate. When treated, 60-90% of patients survive. If untreated it is uniformly fatal.

Viral Pneumonia
Viral agents causing pneumonia include adenoviruses, parainfluenza, respiratory syncytial virus, measles, chicken pox, and influenza. Viral infections in adults are usually mild and limited. Such infections in children are associated with greater severity and may be fatal. Symptoms of acute upper respiratory disease include fever, chills, headache, malaise, anorexia, and general aches. Symptoms usually subside in 2-5 days but may progress to pneumonia in susceptible individuals if the infection spreads to the lower respiratory system. Of greater concern is damage to the respiratory membranes that allows secondary bacterial infections. Sometimes antiviral drugs are used to treat viral pneumonia.

Alternative Names :
Bronchopneumonia, Community-acquired pneumonia , Pneumonitis

Definition :
Pneumonia is an inflammation of the lungs caused by a bacterial, viral, or fungal infection.


  • Cough with mucus-like, greenish, or pus-like sputum
  • chills with shaking
  • fever
  • easy fatigue
  • chest pain
  • sharp or stabbing
  • increased by deep breathing
  • increased by coughing
  • headache
  • loss of appetite
  • nausea and vomiting
  • general discomfort, uneasiness, or ill feeling (malaise)
  • joint stiffness (rare)
  • muscular stiffness (rare)

Additional Symptoms that May be Associated with this Disease:

  • shortness of breath
  • excessive sweating
  • clammy skin
  • nasal flaring
  • coughing up blood
  • rapid breathing
  • anxiety, stress and tension
  • abdominal pain

Causes, Incidence, and Risk Factors
Pneumonia is a very common, often serious illness that affects about 3-4 million people each year in the United States. Many different organisms can cause pneumonia, including bacteria, viruses, and fungi. Bacterial pneumonias tend to be the most serious. In adults, bacteria are the most common cause, and of these Streptococcus pneumoniae (pneumococcus) is the most common.

Respiratory viruses are the most common causes of pneumonia in young children, peaking between the ages of 2 and 3. By school age, the bacterium Mycoplasma pneumoniae becomes more common.
In some people, particularly the elderly and those who are debilitated, pneumonia may follow influenza.

Pneumonia is classified according to a number of different systems. One classification system divides pneumonia into "community-acquired" (pneumonia contracted outside of a health-care institution) and "hospital-acquired" (acquired in a hospital or other long-term health care facility). S. pneumoniae is the most common form of community-acquired pneumonia.

Hospital acquired pneumonia tends to be more serious because the patient's defense mechanisms against infection are often impaired when someone is hospitalized, due to the condition that initially required treatment . In addition, there is a greater possibility of infection with bacteria that are resistant to antibiotics.

Other Classifications of Pneumonia Include:

  • aspiration pneumonia
  • atypical pneumonia
  • bacterial pneumonia
  • CMV pneumonia
  • hospital-acquired pneumonia
  • Legionella pneumonia
  • Mycoplasma pneumonia (walking pneumonia)
  • necrotizing pneumonia
  • pediatric pneumonia
  • Pneumocystis carinii pneumonia
  • pneumonia in immunocompromised host
  • pneumonia with lung abscess
  • pyogenic pneumonia
  • viral pneumonia

If the cause is bacterial, the goal of treatment is to cure the infection with antibiotics. However, if the pneumonia is caused by a virus, antibiotics will NOT be effective.

Supportive therapy includes oxygen and respiratory treatments to remove secretions, if needed.

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