7 Different Types of Pneumonia

The different types of pneumonia can vary in treatment, severity, and cause—here's what you need to know.

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Pneumonia is an infection of the tiny air sacs in the lungs, called alveoli, according to MedlinePlus. These air sacs fill with either pus or fluid and can cause a mild or severe illness, depending on different factors such as your age and the type of pneumonia you have.

There are several different types of pneumonia, and for some people, knowing the kind you have can be crucial in getting you the proper care you need. "The different types of pneumonia can sometimes require very different treatments," said Thomas Monaco, MD, Assistant Professor at the Baylor College of Medicine. "For example, one group of bacteria that causes pneumonia may not respond to the same antibiotic as another group, and antibiotics will not help at all if the cause of the pneumonia is due to a virus or some of the more uncommon causes of pneumonia."

Shweta Sood, MD, MS, a pulmonologist at Penn Medicine, agreed. "For us, it's really helpful to know the type because it influences our therapies for that specific patient, including how aggressive they should be," Dr. Sood said. And once your healthcare provider can figure out the type of pneumonia you have, they can get you the right treatment to help you feel like yourself again.

Here's a breakdown of the different types of pneumonia.

Community-acquired Pneumonia

If you acquire pneumonia in the community (rather than at a hospital) then you may have community-acquired pneumonia, according to MedlinePlus. "Community-acquired pneumonia is someone living their normal life, who gets sick and is diagnosed with pneumonia," Dr. Sood said. "Most of the time, they can be treated safely with rest at home and antibiotics." Bacterial, viral, and walking pneumonia are considered community-acquired pneumonia.

Bacterial Pneumonia

Bacterial pneumonia is a kind of community-acquired pneumonia that is caused by bacteria—most commonly, Streptococcus pneumonia, according to the American Lung Association. This is a bacteria that normally lives in your upper respiratory tract that can make its way down into your lungs and cause an infection, said Raymond Casciari, MD, a pulmonologist at Providence St. Joseph Hospital-Orange.

You can develop this form of pneumonia on its own or after you've had a virus, like the cold or flu. According to the American Lung Association, more than 900,000 people in the United States develop bacterial pneumonia each year. However, Streptococcus pneumoniae isn't the only type of bacteria that can lead to bacterial pneumonia—Dr. Casciari stated that the following types of bacteria could also cause bacterial pneumonia:

  • Mycoplasma pneumoniae
  • Chlamydophila pneumoniae
  • Legionella pneumophila

"We have very good and specific antibiotics to treat bacterial pneumonia," Dr. Sood said. "We need to first identify the bacteria and use the antibody that's specific for that bacteria."

Viral Pneumonia

Ccommunity-acquired pneumonia can also be caused by a virus. This is called viral pneumonia, according to MedlinePlus. These viruses can cause pneumonia:

Unfortunately, antibiotics don't treat viral pneumonia. According to MedlinePlus, there are some other medications that may help if the infection is caught early. This includes antiviral drugs and corticosteroids that will try to reduce inflammation, Dr. Casciari said. In more severe cases, you may need supplemental oxygen as a treatment, according to MedlinePlus. For milder cases of the illness, though, Dr. Sood said your healthcare provider would probably recommend you rest at home and get plenty of fluids.

You do have the option, however, to prevent some of the viruses that can cause pneumonia. The flu, measles, and COVID-19 all have vaccines available to prevent severe illness, according to the U.S. Department of Health and Human Services.

Walking Pneumonia

The last community-acquired pneumonia is walking pneumonia. The term "walking pneumonia" isn't necessarily a true medical diagnosis. "What it implies is that whatever the cause of your pneumonia is, it's not severe enough to put you in bed," Dr. Casciari said. Dr. Sood echoed that statement saying that with walking pneumonia, you can feel sick, "but you're still able to do most activities."

Walking pneumonia can come from any of the main causes of pneumonia—bacterial, viral, or fungal—according to Dr. Casciari. But the American Lung Association says it's most commonly the result of an infection by the Mycoplasma pneumoniae bacteria, which usually causes mild infections in the respiratory system.

Walking pneumonia can be treated with antibiotics, rest, drinking plenty of fluids, and taking fever-reducing medicine (if you have a fever), according to the American Lung Association.

Fungal Pneumonia

Fungal pneumonia isn't common in most parts of the US, and people are usually infected when they breathe in certain fungal spores, Dr. Casciari said. However, there is a condition called valley fever, which is a type of fungal pneumonia caused by the fungus Coccidioides, which lives in soil in the southwestern US, according to the American Lung Association.

Fungal pneumonia is usually more of a concern for people with weakened immune systems, like those who have diabetes, AIDS, or cancer, said Marc Sala, MD, a pulmonologist at Northwestern Medicine. Treatment usually involves antifungal medications like fluconazole, Dr. Casciari said.

Nosocomial Pneumonia

Nosocomial pneumonia is a type of pneumonia that develops after being admitted to a hospital, which can include either hospital-acquired pneumonia or ventilator-associated pneumonia, according to this article from 2022 in StatPearls.

Hospital-acquired pneumonia is different than community-acquired. "That's a term we use for patients that are in the hospital or are going to hospital-like settings and get pneumonia," Dr. Sood said. "They tend to get infected with bugs that require more aggressive therapy and antibiotics."

Nosocomial pneumonia also includes ventilator-associated pneumonia that occurs as a result of ventilator use, according to an article from 2022 in StatPearls. A common way to get hospital-acquired pneumonia is from the use of a ventilator, said Reynold A. Panettieri, Jr., MD, Director of the Rutgers Institute for Translational Medicine and Science. "With a ventilator, the tube goes through your windpipe so you can still maintain oxygen to your heart and brain," Dr. Panettieri explained. "But that tube, which is a foreign object, can be a conduit for any bacteria to get directly into the lungs." People who are on a ventilator are often sick to begin with so adding pneumonia on top of that can be dangerous. "The mortality of that is very high," Dr. Panettieri said.

Chemical Pneumonia

Chemical pneumonia is caused by a toxin you inhale, Dr. Panettieri said. "Classic chemical pneumonia was caused by chlorine gas, which was used as a weapon in World War I." But it's also possible to get chemical pneumonia by accidentally breathing in large amounts of fumes from cleaning supplies, pool equipment, or even air fresheners if they're sprayed directly into someone's airways, Dr. Casciari said. "These things can physically irritate the lungs."

For treatment, corticosteroids can help with inflammation, according to MedlinePlus. Then, healthcare providers will usually provide supportive care until your lungs can heal themselves. "That might involve supplemental oxygen, fluids, and even mechanical ventilation," Dr. Casciari said.

Aspiration Pneumonia

Aspiration pneumonia is an infection that can happen when you accidentally inhale substances into your lungs, like your own stomach acid or food particles, according to MedlinePlus. That causes inflammation and "sometimes this injury can be followed by a secondary bacterial infection," Dr. Monaco said.

This condition is more common in people who have a brain injury, neurological disorder, trouble swallowing, or have used drugs or alcohol—anything that can interfere with the gag reflex that would help keep these substances out of the lungs, Dr. Casciari said.

Treatment for aspiration pneumonia varies: "If the aspiration is small in amount and there is no sign of a secondary infection, we usually treat it supportively with oxygen and prevention of further aspiration," Dr. Monaco said. "Most patients recover fully." If there's a lot of stuff in your airways, you may need a breathing tube and a procedure called a bronchoscopy to help remove everything, Dr. Monaco said, adding that antibiotics may also be needed.

Summary

Pneumonia can be caused by various bacteria, fungi, or viruses, according to the American Lung Association. By diagnosing the type of pneumonia you have, you are one step closer to treating it. Whether you need rest, antibiotics, or supplemental oxygen—your healthcare provider can determine which kind of pneumonia you have and guide you through treatment.

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