What is pneumonia?

Pneumonia is an infection of one or
both of the lungs caused by bacteria, viruses, or fungi. It is a serious infection in
which the air sacs fill with pus and other liquid.

  • Lobar pneumonia affects one or more sections (lobes) of the lungs.
  • Bronchial pneumonia  affects patches
    throughout both lungs. It is also called bronchopneumonia.

What causes pneumonia?

There are more than 30 different causes of pneumonia, and they’re grouped by the cause. The main types of pneumonia are:

  • Bacterial pneumonia. This type is
    caused by various bacteria. The most common is Streptococcus pneumoniae

    . It often occurs
    when the body is weakened in some way. This may be from illness, poor nutrition,
    older age, or impaired immunity. Then the bacteria can work their way into the lungs.
    Bacterial pneumonia can affect all ages. But you are at greater risk if you abuse
    alcohol, smoke, are weak, have just had surgery, have a respiratory disease or viral
    infection, or have a weakened immune system.
  • Viral pneumonia. This type is caused
    by different viruses, including the flu. It is responsible for about one-third of
    all pneumonia cases. You may be more likely to get bacterial pneumonia if you have
    viral pneumonia.
  • Mycoplasma pneumonia. This type has
    somewhat different symptoms and physical signs. It is called an atypical pneumonia.
    It is caused by the bacteria Mycoplasma pneumoniae. It generally causes a mild,
    widespread pneumonia that affects all age groups.
  • Other pneumonias. There are other less common pneumonias that may be caused by other infections including fungi.

Who is at risk for pneumonia?

Anyone can get pneumonia. But the
following groups are at the highest risk:

  • Adults ages 65 and older
  • Children younger than age 2
  • People with certain health
  • People who smoke

What are the symptoms of pneumonia?

The symptoms of bacterial pneumonia include:

  • Bluish color to lips and fingernails
  • Confused mental state or delirium, especially in older people
  • Cough that produces green, yellow, or bloody mucus
  • Fever
  • Heavy sweating
  • Loss of appetite
  • Low energy and extreme tiredness
  • Rapid breathing
  • Rapid pulse
  • Shaking chills
  • Sharp or stabbing chest pain that’s worse with deep breathing or coughing
  • Shortness of breath that gets worse with activity

Early symptoms of viral pneumonia are the same as those of bacterial pneumonia, which may be followed by:

  • Headache
  • Increasing shortness of breath
  • Muscle pain
  • Weakness
  • Worsening of the cough

Mycoplasma pneumonia has somewhat
different symptoms. These include a severe cough that may produce mucus.

How is pneumonia diagnosed?

Diagnosis is often made based on
your recent health history such as surgery, a cold, or travel exposures. Your healthcare
provider will also note the extent of the illness. Based on these factors, your provider
may diagnose pneumonia simply on a thorough history and physical exam. These tests may
be used to confirm the diagnosis:

  • Chest X-ray. This test takes pictures of internal tissues, bones, and organs, including the lungs.
  • Blood tests. This test may be used to
    see if infection is present and if infection has spread to the bloodstream (blood
    cultures). Arterial blood gas testing checks the amount of oxygen in your
  • Sputum culture. This test is done on the material that is coughed up from the lungs and into the mouth. It’s often used to see if there’s an infection in the lungs.
  • Pulse oximetry. An oximeter is a small machine that measures the amount of oxygen in the blood. A small sensor is taped or clipped onto a finger. When the machine is on, a small red light can be seen in the sensor. The test is painless and the red light does not get hot.
  • Chest CT scan. This imaging procedure
    uses a combination of X-rays and computer technology to make sharp, detailed
    horizontal, or axial, images (often called slices) of the body. A CT scan shows
    detailed images of any part of the body, including the bones, muscles, fat, and
    organs. CT scans are more detailed than regular X-rays.
  • Bronchoscopy. This is direct exam of
    the main airways of the lungs (bronchi) using a flexible tube (bronchoscope). It
    helps to check and diagnose lung problems, assess blockages, and take out samples of
    tissue or fluid for testing,
  • Pleural fluid culture. In this test,
    a fluid sample is taken from the pleural space. This is the space between the lungs
    and chest wall. A long, thin needle is put through the skin between the ribs and into
    the pleural space. Fluid is pulled into a syringe attached to the needle. It is sent
    to the lab where it’s tested to find out which bacteria is causing the