Pneumonia

Definition

Pneumonia is a respiratory condition in which there is infection of the lung.

Community-acquired pneumonia refers to pneumonia in people who have not recently been in the hospital or another health care facility (nursing home, rehabilitation facility).

See also: Hospital-acquired pneumonia

Causes, incidence, and risk factors

Pneumonia is a common illness that affects millions of people each year in the United States. Germs called bacteria, viruses, and fungi may cause pneumonia.

Ways you can get pneumonia include:

• Bacteria and viruses living in your nose, sinuses, or mouth may spread to your lungs.
• You may breathe some of these germs directly into your lungs.
• You breathe in (inhale) food, liquids, vomit, or secretions from the mouth into your lungs (aspiration pneumonia)

Pneumonia caused by bacteria tends to be the most serious. In adults, bacteria are the most common cause of pneumonia.

• The most common pneumonia-causing germ in adults is Streptococcus pneumoniae (pneumococcus).
• Atypical pneumonia, often called walking pneumonia, is caused by bacteria such as Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydophila pneumoniae.
• Pneumocystis jiroveci pneumonia is sometimes seen in people whose immune system is impaired (due to AIDS or certain medications that suppress the immune system).
• Staphylococcus aureus , Moraxella catarrhalis , Streptococcus pyogenes , Neisseria meningitidis , Klebsiella pneumoniae , or Haemophilus influenzae are other bacteria that can cause pneumonia.
• Tuberculosis can cause pneumonia in some people, especially those with a weak immune system.

Viruses are also a common cause of pneumonia, especially in infants and young children.

See also: Respiratory syncytial virus

Risk factors (conditions that increase your chances of getting pneumonia) include:

• Cerebral palsy
• Chronic lung disease (COPD, bronchiectasis, cystic fibrosis)
• Cigarette smoking
• Difficulty swallowing (due to stroke, dementia, Parkinson's disease, or other neurological conditions)
• Immune system problem (See also: Pneumonia in immunocompromised host)
• Impaired consciousness (loss of brain function due to dementia, stroke, or other neurologic conditions)
• Living in a nursing facility
• Other serious illnesses, such as heart disease, liver cirrhosis, or diabetes mellitus
• Recent surgery or trauma
• Recent viral respiratory infection (common cold, laryngitis, influenza)  

Alternative Names

Bronchopneumonia; Community-acquired pneumonia

Symptoms

The most common symptoms of pneumonia are:

• Cough (with some pneumonias you may cough up greenish or yellow mucus, or even bloody mucus )
• Fever , which may be mild or high
• Shaking chills
• Shortness of breath (may only occur when you climb stairs)

Additional symptoms include:

• Confusion , especially in older people
• Excessive sweating and clammy skin
• Headache
• Loss of appetite , low energy, and fatigue
• Sharp or stabbing chest pain that gets worse when you breathe deeply or cough

Signs and tests

If you have pneumonia, you may be working hard to breathe, or 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:

• Arterial blood gases to see if enough oxygen is getting into your blood from the lungs
• CBC to check white blood cell count
• CT scan of the chest
• Gram's stain and culture of your sputum to look for the organism causing your symptoms
• Pleural fluid culture if there is fluid in the space surrounding the lungs 

Treatment

Your doctor must first decide whether you need to be in the hospital. If you are treated in the hospital, you will receive fluids and antibiotics in your veins, oxygen therapy, and possibly breathing treatments. It is very important that your antibiotics are started very soon after you are admitted.

You are more likely to be admitted to the hospital if you:

• Have another serious medical problem
• Have severe symptoms
• Are unable to care for yourself at home, or are unable to eat or drink
• Are older than 65 or a young child
• Have been taking antibiotics at home and are not getting better

However, many people can be treated at home. If bacteria are causing the pneumonia, the doctor will try to cure the infection with antibiotics. It may be hard for your health care provider to know whether you have a viral or bacterial pneumonia, so you may receive antibiotics.

Patients with mild pneumonia who are otherwise healthy are sometimes 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], gemifloxacin [Factive], or moxifloxacin [Avelox])
• High-dose amoxicillin or amoxicillin-clavulanate, plus a macrolide antibiotic (azithromycin, clarithromycin, or erythromycin)
• Cephalosporin antibiotics (for example, cefuroxime or cefpodoxime) plus a macrolide (azithromycin, clarithromycin, or erythromycin)

If the cause is a virus, typical antibiotics will NOT be effective. Sometimes, however, your doctor may use antiviral medication.

You can take these steps at home:

• Control your fever with aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen or naproxen), or acetaminophen. DO NOT give aspirin to children.
• Do not take cough medicines without first talking to your doctor. Cough medicines may make it harder for your body to cough up the extra sputum.
• Drink plenty of fluids to help loosen secretions and bring up phlegm.
• Get lots of rest. Have someone else do household chores.

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.

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

• A drug called Synagis (palivizumab) is given to some children younger than 24 months to prevent pneumonia caused by respiratory syncytial virus.
• Flu vaccine prevents pneumonia and other problems caused by the influenza virus. It must be given yearly to protect against new virus strains.
• Hib vaccine prevents pneumonia in children from Haemophilus influenzae type b.
• Pneumococcal vaccine (Pneumovax, Prevnar) lowers your chances of getting pneumonia from Streptococcus pneumoniae.

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