Definition

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

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

Alternative Names

Bronchopneumonia; Community-acquired pneumonia

Causes, incidence, and risk factors

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.

People who have trouble swallowing are at risk of aspiration pneumonia. In this condition, food, liquid, or saliva accidentally goes into the airways. It is more common in people who have had a stroke, Parkinson's disease, or previous throat surgery.

It is often harder to treat pneumonia in people who are in a hospital, or a nursing facility.

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

Additional symptoms include:

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

Signs 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 health care provider will likely order a chest x-ray if pneumonia is suspected.

Some patients may need other tests, including:

• 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

Treatment

If the cause is bacterial, the doctor will try to cure the infection with antibiotics. If the cause is viral, typical antibiotics will NOT be effective. Sometimes, however, your doctor may use antiviral medication. It may be difficult to distinguish between viral and bacterial pneumonia, so you may receive antibiotics.

Patients with mild pneumonia who are otherwise healthy are usually treated with oral macrolide antibiotics (azithromycin, clarithromycin, or erythromycin).

Patients with other serious illnesses, such as heart disease, chronic obstructive pulmonary disease, or emphysema, kidney disease, or diabetes are often given one of the following:

• Fluoroquinolone (levofloxacin (Levaquin), sparfloxacin (Zagam), or gemifloxacin (Factive), moxifloxacin (Avelox)
• High-dose amoxicillin or amoxicillin-clavulanate, plus a macrolide antibiotic (azithromycin, clarithromycin, or erythromycin)

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.

Expectations (prognosis)

With treatment, most patients will improve within 2 weeks. Elderly or debilitated patients may need treatment for longer.

Your doctor will want to make sure your chest x-ray becomes normal again after you take a course of antibiotics.

Complications

Empyema or lung abscesses 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.

Calling your health care provider

Call your doctor if you have:

• Worsening respiratory symptoms
• Shortness of breath, shaking chills, or persistent fevers
• Rapid or painful breathing
• A cough that brings up bloody or rust-colored mucus
• Chest pain that worsens when you cough or inhale
• Night sweats or unexplained weight loss
• Signs of pneumonia and 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.

Prevention

• 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 problems caused by the influenza virus. 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.

References

Limper AH. Overview of Pneumonia. In: Goldman L, Ausiello D. Goldman: Cecil Medicine. 23rd ed. Philadelphia, PA: Saunders Elsevier; 2007:chap 97.

Lutfiyya MN, Henley E, Chang LF, Reyburn SW. Diagnosis and treatment of community-acquired pneumonia. Am Fam Physician. 2006;73:442-450.

Hemilä H, Louhiala P. Vitamin C for preventing and treating pneumonia. Cochrane Database Syst Rev. 2007;Jan 24(1):CD005532.

Committee on Infectious Diseases. Recommended immunization schedules for children and adolescents -- United States, 2008. Pediatrics. 2008;121:219-220.

Li JZ, Winston LG, Moore DH, Bent S. Efficacy of short-course antibiotic regimens for community-acquired pneumonia: a meta-analysis. Am J Med. 2007;120:783-790.

Mandell LA, Wunderink RG, Anzueto A, et al. Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults. Clin Infect Dis. 2007 Mar 1;44 Suppl 2:S27-72.