Pneumonia

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Pneumonia

Definition

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

Alternative Names

Bronchopneumonia; Community-acquired pneumonia

Causes

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

Bacterial pneumonias tend to be the most serious and, in adults , the most common cause of pneumonia. The most common pneumonia-causing bacterium in adults is 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

Symptoms

The main symptoms of pneumonia are:

• 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 , especially in older people

Exams and Tests

If you have pneumonia , you may be working hard to breathe, or may be breathing fast. Crackles are heard when listening to your chest with a stethoscope. Other abnormal breathing sounds may also be heard through the stethoscope or via percussion (tapping on your chest wall).

The following tests may show signs of pneumonia:

• 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
• CAT scan of the chest
• Pleural fluid culture if there is fluid in the space surrounding the lungs