In short

Bacterial pneumonia is a serious lung infection that can range from mild to life-threatening, affecting millions of people each year and requiring prompt medical attention to prevent complications and ensure full recovery.

What Is Bacterial Pneumonia?

Bacterial pneumonia is an infection of your lungs caused by harmful bacteria. When you have this condition, your lung tissue swells up and becomes inflamed. The tiny air sacs in your lungs, called alveoli (the small balloon-like structures where oxygen enters your blood), fill up with fluid or pus instead of air. This makes it very difficult to breathe properly and prevents enough oxygen from getting into your bloodstream.

The word "pneumonia" comes from an ancient Greek word meaning "lung," so pneumonia simply means "lung disease." While pneumonia can be caused by viruses, fungi, or parasites, bacterial pneumonia tends to be more common and usually more severe than other types. It is more likely to require hospitalization and can cause serious complications if not treated properly.

Bacterial pneumonia can affect one or both lungs. When both lungs are infected, doctors call this bilateral or double pneumonia.

Lungs
Alveoli (air sacs)
Lung parenchyma (lung tissue)

What Causes Bacterial Pneumonia?

Several types of bacteria can cause pneumonia, with some being more common than others. The most common cause of bacterial pneumonia is a bacterium called Streptococcus pneumoniae, also known as pneumococcus. This is especially true for community-acquired pneumonia (pneumonia you get outside of a hospital or healthcare facility).

Other bacteria that can cause pneumonia include:

Mycoplasma pneumoniae, which causes a milder form called atypical pneumonia
Haemophilus influenzae
Chlamydia pneumoniae
Legionella, which causes Legionnaires' disease

If you are young and generally healthy, these bacteria can sometimes live in your throat without causing any problems. However, when your body's defense system (immune system) becomes weak for some reason, the bacteria can travel down into your lungs. Once there, they multiply and cause infection, leading to inflammation and fluid buildup in the air sacs.

Hospital-acquired pneumonia and healthcare-associated pneumonia are often more serious because they are frequently caused by bacteria that have become resistant to many antibiotics, such as methicillin-resistant Staphylococcus aureus (MRSA). This means these infections can be harder to treat.

Who Is at Risk?

Anyone can develop bacterial pneumonia, but certain groups of people face higher risks. Your chances of getting bacterial pneumonia increase if you:

Are 65 years old or older
Are a child younger than 5 years old
Have other health conditions like asthma, diabetes, or heart disease
Have chronic obstructive pulmonary disease (COPD)
Are recovering from surgery
Don't eat a balanced diet or lack proper vitamins and minerals
Have a weakened immune system
Smoke cigarettes or are exposed to secondhand smoke
Drink too much alcohol
Have recently had viral pneumonia

People with weakened immune systems face especially high risks. This includes individuals who have recently had an organ transplant, those who are HIV positive, or people with leukemia, lymphoma, or severe kidney disease.

Signs and Symptoms

The symptoms of bacterial pneumonia can develop quickly and be quite severe, or they may appear gradually over a few days. Common symptoms include:

High fever, which can reach up to 105°F (about 40.5°C)
Cough that produces mucus or phlegm. The mucus may be greenish, yellow, or even bloody
Chills that make you shake
Shortness of breath or feeling like you can't catch your breath, especially when you move around
Chest pain when you breathe deeply or cough
Feeling very tired or exhausted
Loss of appetite
Sweating heavily
Fast breathing and rapid heartbeat
Nausea, vomiting, or diarrhea
Blue color in your lips and fingernails (a sign of low oxygen)
Confusion, especially in older adults

The type of mucus you cough up can sometimes give clues about which bacteria is causing the infection. For example, rust-colored sputum may suggest Streptococcus pneumoniae, while red currant-jelly sputum may indicate Klebsiella species pneumonia. Foul-smelling or bad-tasting sputum often points to an infection caused by anaerobic bacteria.

In adults older than 65, symptoms may be different and include lower than normal body temperature and confusion or changes in mental awareness.

How Is It Diagnosed?

Your doctor will start by asking about your medical history and symptoms, then perform a physical examination. During the exam, your doctor will listen to your lungs with a stethoscope to check for abnormal sounds that suggest pneumonia, such as crackling or bubbling noises, decreased breath sounds, or wheezing.

If your doctor suspects pneumonia, several tests may be recommended:

Chest X-ray: This imaging test helps your doctor see the infection in your lungs and determine how widespread it is
Blood tests: These help confirm that there is an infection and may help identify which bacteria is causing it
Pulse oximetry: A small device clipped to your finger measures how much oxygen is in your blood
Sputum test: A sample of the mucus you cough up is examined in a laboratory to identify the specific bacteria causing the infection

For older adults, those already in the hospital, or people with serious symptoms or other health conditions, additional tests might be needed. These can include:

CT scan: This provides more detailed images of your lungs if the pneumonia isn't clearing up as expected
Pleural fluid culture: If fluid has collected around your lungs, a sample may be taken with a needle and tested to determine the type of infection

Treatment Options

The main treatment for bacterial pneumonia is antibiotics. These medicines kill the bacteria causing the infection. It is extremely important that you take all of the antibiotics exactly as your doctor prescribes them. Even if you start feeling better before the medicine is finished, you must continue taking it until it's all gone. Stopping too early can allow the bacteria to survive and multiply again, causing your pneumonia to come back. The bacteria may also become resistant to the antibiotic, making treatment much more difficult.

Besides antibiotics, your doctor may suggest other measures to help you feel better:

Over-the-counter pain medicines like acetaminophen (Tylenol), ibuprofen (Advil, Motrin), or naproxen (Aleve) to reduce fever and discomfort
Cough medicine if your cough is preventing you from resting, though you should talk to your doctor first because coughing helps clear mucus from your lungs
Using a vaporizer or humidifier to add moisture to the air in your bedroom
Getting plenty of rest and sleep

For patients with mild shortness of breath, supplemental oxygen delivered through a nasal tube may be needed. Those who are more seriously ill may require hospitalization for intravenous antibiotics, breathing support, or treatment of complications.

Recovery and Getting Stronger

It may take time to fully recover from bacterial pneumonia. Some people feel better and can return to their normal routines in one to two weeks, while for others it can take a month or longer. Most people continue to feel tired for about a month after their infection clears.

The recovery time depends on several factors including your age, how severe your illness was, and whether you have other health conditions. Young, healthy people with mild pneumonia typically recover faster. Recovery is often longer for older adults or those who were hospitalized with severe pneumonia.

During recovery, it's important to:

Continue taking all medicines as prescribed
Eat heart-healthy, nutritious foods to help your body heal
Drink plenty of fluids to stay hydrated
Get plenty of sleep and rest
Avoid alcohol and illegal drugs, which can weaken your immune system
Stay away from cigarette smoke and don't smoke
Slowly return to physical activity, starting with light exercise like short walks

If you feel chest pain, severe shortness of breath, or dizziness when trying to exercise, stop and contact your doctor. While recovering at home, turn over in bed at least every hour when awake, and practice breathing deeply five to ten times followed by coughing to help clear mucus from your lungs.

After severe pneumonia, your body may be extremely weak. Full recovery can take several months, and you may need extra support from family or caregivers during this time. Some people may experience long-term effects on lung function or develop scarring in the lungs.

How to Prevent Bacterial Pneumonia

There are several effective ways to lower your risk of getting bacterial pneumonia or prevent it from happening again:

Get vaccinated: Two types of pneumonia vaccines are available:

PCV13 (Prevnar 13) is recommended for people 65 or older, children under 5 years old, and people at high risk of bacterial pneumonia
PPSV23 (Pneumovax) is recommended for people 65 or older, children over 2 who have high risk factors, and people between 19 and 64 who smoke or have asthma

Talk to your doctor about which vaccines you or your child should receive. You should also get yearly influenza (flu) vaccines and stay up to date on COVID-19 vaccinations, since viral infections can lead to bacterial pneumonia.

Practice healthy living habits:

Wash your hands regularly, especially after using the bathroom and before eating
Eat a balanced diet with plenty of fruits and vegetables
Exercise regularly
Get enough sleep
Quit smoking or don't start
Avoid people who are sick when possible
Stay away from others when you are sick
Clean and disinfect surfaces that are touched frequently
Take good care of your teeth and gums, which may help prevent some types of pneumonia
Cover your cough or sneeze with a tissue or your elbow

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