Pneumonia

Definition

Pneumonia is an infection that inflames the air sacs in one or both lungs. The air sacs may fill with fluid or pus, causing cough with phlegm or pus, fever, chills and difficulty breathing.

A variety of organisms, including bacteria, viruses and fungi, can cause pneumonia.

Pneumonia can range in seriousness from mild to life-threatening. It is most serious for infants and young children, people older than age 65, and people with underlying health problems or weakened immune systems.

Antibiotics and antiviral medications can treat many common forms of pneumonia.

Symptoms

The signs and symptoms of pneumonia vary from mild to severe, depending upon factors such as the type of germ causing the infection and your age and overall health. Mild signs and symptoms often are similar to those of a cold or flu, but they last longer.

Signs and symptoms of pneumonia include:

• Fever, sweating and shaking chills
• Lower than normal body temperature in people older than age 65, and in people with poor overall health or weakened immune systems
• Cough, which may produce thick, sticky fluid
• Chest pain when you breathe deeply or cough
• Shortness of breath
• Fatigue and muscle aches
• Nausea, vomiting or diarrhea
• Headache

Newborns and infants may not show any sign of the infection. Or they may vomit, have a fever and cough, appear restless or tired and without energy, or have difficulty breathing and eating.

Older people who have pneumonia sometimes have sudden changes in mental awareness.

WHEN TO SEE A DOCTOR 
See your doctor if you have difficulty breathing, chest pain, persistent fever of 39 C or higher or persistent cough, especially if you are coughing up pus.

It's especially important to see a doctor if:

• A child with signs and symptoms is younger than age 2
• You are older than age 65
• You have an underlying health condition or weakened immune system
• You're having chemotherapy or taking medication that suppresses your immune system

For some older adults and people with heart failure or lung ailments, pneumonia can quickly become a life-threatening condition.

Causes

Pneumonia has many possible causes. The most common are bacteria and viruses in the air we breathe. Your body usually prevents these germs from infecting your lungs. But sometimes these germs can overpower your immune system, even if your health is generally good.

Pneumonia is classified according to the types of germs that cause it, and where you acquired the infection.

Community-acquired pneumonia 
Community-acquired pneumonia is the most common type of pneumonia. It occurs outside of hospitals and other health care facilities, and may be caused by:

• Bacteria, such as Streptococcus pneumoniae. Bacterial community-acquired pneumonia can occur on its own or after you have a cold or respiratory flu. This type of pneumonia often affects one area (lobe) of the lung, a condition called lobar pneumonia.

• Bacteria-like organisms, such as Mycoplasma pneumoniae, which typically produce milder signs and symptoms than do other types of pneumonia. "Walking pneumonia," a term used to describe pneumonia that isn't severe enough to require bed rest, may result from Mycoplasma pneumoniae.

• Viruses, including some that are the same type of viruses that cause colds and flu. Viruses are the most common cause of pneumonia in children younger than 2 years. Viral pneumonia is usually mild. But viral pneumonia caused by certain influenza viruses, such as sudden acute respiratory syndrome (SARS), can become very serious.

• Fungi, which can be found in soil and in bird droppings. This type of pneumonia is most common in people with an underlying health problem or weakened immune system and in people who have inhaled a large dose of the organisms.

Hospital-acquired pneumonia 

Hospital-acquired pneumonia is a bacterial infection that occurs in people 48 hours or more after being hospitalized for another condition. Hospital-acquired pneumonia can be serious because the bacteria causing it may be more resistant to antibiotics.

People who are on a breathing machine (ventilator), often used in intensive care units, are at higher risk of this type of pneumonia.

Health care-acquired pneumonia 
Health care-acquired pneumonia is a bacterial infection that occurs in people who are living in long-term care facilities or have been treated in outpatient clinics, including kidney dialysis centers. Like hospital-acquired pneumonia, health care-acquired pneumonia can be caused by bacteria more resistant to antibiotics.

Aspiration pneumonia 
Aspiration pneumonia occurs when you inhale food, drink, vomit or saliva into your lungs. This aspiration may happen if something disturbs your normal gag reflex, such as a brain injury, swallowing problem, or excessive use of alcohol or drugs.

Risk factors

Pneumonia can affect anyone. But the two age groups at highest risk are:

• Infants and children younger than age 2 years, because their immune systems are still developing
• People older than age 65

Other risk factors include:

• Certain chronic diseases, such as asthma, chronic obstructive pulmonary disease and heart disease
• Weakened or suppressed immune system, due to factors such as HIV/AIDS, organ transplant, chemotherapy for cancer or long-term steroid use
• Smoking, which damages your body's natural defenses against the bacteria and viruses that cause pneumonia
• Being placed on a ventilator while hospitalized

Complications

Often, people who have pneumonia can be treated successfully with medication. But some people, especially those in high-risk groups, may experience complications, including:

• Bacteria in the bloodstream (bacteremia). Bacteria that enter the bloodstream from your lungs can spread the infection to other organs, potentially causing organ failure.
• Lung abscess. An abscess occurs if pus forms in a cavity in the lung. An abscess is usually treated with antibiotics. Sometimes, surgery or drainage with a long needle or tube placed into the abscess is needed to remove the pus.
• Fluid accumulation around your lungs (pleural effusion). Pneumonia may cause fluid to build up in the thin space between layers of tissue that line the lungs and chest cavity (pleura). If the fluid becomes infected, you may need to have it drained through a chest tube or removed with surgery.
• Difficulty breathing. If your pneumonia is severe or you have chronic underlying lung diseases, you may have trouble breathing in enough oxygen. You may need to be hospitalized and use a mechanical ventilator while your lung heals.

Tests and diagnosis

Your doctor will start by asking about your medical history and doing a physical exam, including listening to your lungs with a stethoscope to check for abnormal bubbling or crackling sounds that indicate the presence of thick liquid.

If pneumonia is suspected, your doctor may recommend:

• Chest X-rays, to confirm the presence of pneumonia and determine the extent and location of the infection.
• Blood tests, to confirm the presence of infection and to try to identify the type of organism causing the infection. Precise identification occurs in only about half of people with pneumonia.
• Pulse oximetry, to measure the oxygen level in your blood. Pneumonia can prevent your lungs from moving enough oxygen into your bloodstream.
• Sputum test. A sample of fluid from yours lungs (sputum) is taken after a deep cough, and analyzed to pinpoint the type of infection.

If you are older than age 65, are in the hospital or have serious symptoms or an underlying health condition, your doctor may recommend:

• Pleural fluid culture. A fluid sample is taken from the pleural area and analyzed to help determine the type of infection.
• Bronchoscopy. A thin, flexible tube with a camera is inserted down your throat and through your airways to check whether something is blocking the airways or whether something else is contributing to your pneumonia.

If your pneumonia isn't clearing as quickly as expected, your doctor may recommend a chest CT scan to obtain a more detailed image of your lungs.

Treatments and drugs

Treatment for pneumonia involves curing the infection and preventing any complications.

People who have community-acquired pneumonia usually can be treated at home with medication. Although your symptoms may ease in a few days or weeks, tiredness can persist for a month or more.

Your doctor will likely recommend a follow-up chest X-ray to check that the infection is clearing. It may be safe to stop treatment even if your X-ray isn't completely normal. Only about half of chest X-rays in people with community-acquired pneumonia are normal after 28 days of treatment.

Specific treatments depend on the type and severity of your pneumonia, and your age and overall health. The options include:

• Antibiotics, to treat bacterial pneumonia. It may take time to identify the type of bacteria causing your pneumonia and to choose the best antibiotic to treat it. Symptoms often improve within three days, although improvement usually takes twice as long in smokers. If your symptoms don't improve, your doctor may recommend a different antibiotic.
• Antiviral medications, to treat viral pneumonia. Symptoms generally improve in one to three weeks.
• Fever reducers, such as aspirin or ibuprofen.
• Cough medicine, to calm your cough so you can rest. Because coughing helps loosen and move fluid from your lungs, it's a good idea not to eliminate your cough completely.

Hospitalization

You may need to be hospitalized if:

• You are older than age 65
• You become confused about time, people or places
• Your nausea and vomiting prevent you from keeping down oral antibiotics
• Your blood pressure drops
• Your breathing is rapid
• You need breathing assistance
• Your temperature is below normal

If you need to be placed on a ventilator or your symptoms are severe, you may need to be admitted  to an intensive care unit.

Children may be hospitalized if they:

• Are younger than age 3 months
• Are excessively sleepy
• Have trouble breathing
• Have low blood oxygen levels
• Appear dehydrated
• Have a lower than normal temperature

Lifestyle and home remedies

To help you recover more quickly and decrease your risk of complications:

• Get plenty of rest. Even when you start to feel better, be careful not to overdo it.
• Stay home from school or work until after your temperature returns to normal and you stop coughing up mucus. Because pneumonia can recur, it's better not to return to a full workload until you're sure you're well. Ask your doctor if you're not sure.
• Drink plenty of fluids, especially water, to help loosen mucus in your lungs.
• Take the entire course of any prescribed medications. If you stop medication too soon, your lungs may continue to harbor bacteria that can multiply and cause your pneumonia to recur.

Prevention

To help prevent pneumonia:

• Get a seasonal flu shot. The influenza virus can be a direct cause of viral pneumonia. Bacterial pneumonia is also a common complication of the flu. A yearly flu shot provides significant protection.
• Link to the Vaccination
• Get a pneumonia vaccination. Doctors recommend a one-time vaccine against Streptococcus pneumoniae bacteria (pneumococcus) for everyone older than age 65, as well as for people of any age residing in nursing homes and long-term care facilities, and for smokers. The vaccine is especially recommended for anyone at high risk of pneumococcal pneumonia. Some doctors recommend a booster shot five years after the first dose.
• Have your child vaccinated. Doctors recommend a different pneumonia vaccine for all children younger than age 2 and for children ages 2 to 5 years who are at particular risk of pneumococcal disease. Children who attend a group day care center should also get the vaccine. Doctors also recommend seasonal flu shots for children older than six months.
• Practice good hygiene. To protect yourself against ordinary respiratory infections that sometimes lead to pneumonia, wash your hands regularly or use an alcohol-based hand sanitizer.
• Don't smoke. Smoking damages your lungs' natural defenses against respiratory infections.
• Stay rested and fit. Proper rest, a healthy diet and moderate exercise can help keep your immune system strong.
• Set an example. Stay home when you're sick. When you're in public and have a cold, catch your coughs and sneezes in the inner crook of your elbow.

Source: http://www.nhlbi.nih.gov/health/health-topics/topics/pnu/