Pneumonia is an inflammation of the lungs caused by an infection. Many different organisms can cause it, including bacteria, viruses, and fungi.

Pneumonia is a common illness that affects millions of people each year in the United States.

Pneumonia can range from mild to severe, even fatal. The severity depends on the type of organism causing pneumonia as well as your age and underlying health.

Bacterial pneumonias tend to be the most serious and, in adults, the most common cause, especially Streptococcus pneumoniae (pneumococcus).

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, bacterial pneumonia may follow influenza or even a common cold.

Many people contract pneumonia while staying in a hospital for other conditions. This tends to be more serious because the patient's immune system is often impaired due to the condition that initially required treatment. In addition, there is a greater possibility of infection with bacteria that are resistant to antibiotics.

See also:

• aspiration pneumonia
• atypical pneumonia
• CMV pneumonia
• hospital-acquired pneumonia
• Legionella pneumonia
• Pneumocystis carinii pneumonia
• pneumonia in immunocompromised host
• viral pneumonia
• walking pneumonia

• Cough with greenish or yellow mucus; bloody sputum happens on occasion
• Fever with shaking chills
• Sharp or stabbing chest pain worsened by deep breathing or coughing
• Rapid, shallow breathing
• Shortness of breath

• Headache
• Excessive sweating and clammy skin
• Loss of appetite
• Excessive fatigue
• Confusion in older people

• Chest x-ray
• Gram's stain and culture of your sputum to look for the organism causing your symptoms
• CBC to check white blood cell count; if high, this suggests bacterial infection
• Arterial blood gases to check how well you are oxygenating your blood
• Thoracic CT
• Pulmonary ventilation/perfusion scan
• Pleural fluid culture if there is fluid in the space surrounding the lungs

If the cause is bacterial, the goal is to cure the infection with antibiotics. If the cause is viral, antibiotics will NOT be effective. In some cases it is difficult to distinguish between viral and bacterial pneumonia, so antibiotics may be prescribed.

Many people can be treated at home with antibiotics. If you have an underlying chronic disease, severe symptoms, or low oxygen levels, you will likely require hospitalization for intravenous antibiotics and oxygen therapy. Infants and the elderly are more commonly admitted for treatment of pneumonia.

You can take these steps at home:

• Drink plenty of fluids to help loosen secretions and bring up phlegm.
• Get lots of rest. Have someone else do household chores.
• Control your fever with aspirin or acetaminophen. DO NOT give aspirin to children.

When in the hospital, respiratory treatments to remove secretions may be necessary. Occasionally, steroid medications may be used to reduce wheezing if there is an underlying lung disease.

Empyemae or lung abcesses are infrequent, but serious, complications of pneumonia. They occur when pockets of pus form around or inside the lung. These may sometimes require surgical drainage.

Call your doctor if:

• You have worsening respiratory symptoms.
• You have shortness of breath, shaking chills, or persistent fevers.
• Your breathing is rapid or painful.
• You cough up bloody or rust-colored mucus.
• You have chest pain that worsens when you cough or inhale.
• You have night sweats or unexplained weight loss.
• You have a weak immune system, as with HIV or chemotherapy.

Infants with pneumonia may not have a cough. Call your doctor if your infant makes grunting noises or the area below the rib cage is retracting while breathing.

• Wash your hands frequently, especially after blowing your nose, going to the bathroom, diapering, and before eating or preparing foods.
• Don't smoke. Tobacco damages your lung's ability to ward off infection.
• Wear a mask when cleaning dusty or moldy areas

Vaccines can help prevent pneumonia in children, the elderly, and people with diabetes, asthma, emphysema, HIV, cancer, or other chronic conditions:

• Pneumococcal vaccine (Pneumovax, Prevnar) prevents Streptococcus pneumoniae.
• Flu vaccine prevents pneumonia and other infections caused by influenza viruses. It must be given yearly to protect against new viral strains.
• Hib vaccine prevents pneumonia in children from Haemophilus influenzae type b.

Taking deep breaths may help prevent pneumonia if you are in the hospital -- for example, while recovering from surgery. Often, a breathing device will be given to you to assist in deep breathing.

If you have cancer or HIV, you should talk to your doctor about additional ways to prevent pneumonia.