What Is Chlamydia Pneumoniae?

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When people think of chlamydia, they're usually thinking of the bacteria that are sexually transmitted. However, there are other bacterial species within the genus Chlamydia, including Chlamydia pneumoniae (C. pneumoniae). This strain is spread by contact through respiratory droplets and typically causes sinusitis, bronchitis, pharyngitis, and pneumonia.

It's not clear how many people become infected with Chlamydia pneumoniae. However, many people who do get it are able to clear a mild infection on their own. Older people and some other groups are at a higher risk for more severe infections.

Read on for more information on the causes, symptoms, diagnosis, and treatment of Chlamydia pneumoniae.

Person laying down on couch while blowing their nose and reading their temperature on an electronic thermometer

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Chlamydia pneumoniae can spread from one person to another through respiratory droplets. This typically occurs when a person who is infected sneezes or coughs.

People who have only brief contact with a person who has C. pneumoniae are unlikely to get sick. It's more common that a person who is infected will transmit the bacterium to someone who lives with them or is around them for prolonged periods of time.

Higher Risk Settings for Chlamydia Pneumoniae Infections

Prolonged contact with a person who is infected with the bacterium is more likely to result in an infection. Working or living in a crowded or densely populated environment can increase your risk of being exposed and becoming ill with chlamydia pneumoniae. These settings may include:

  • Schools
  • Residential halls or housing at universities and colleges
  • Hospitals
  • Long-term care facilities, such as assisted living or nursing homes
  • Correctional facilities
  • Military barracks


Many people who have a C. pneumoniae infection will have mild symptoms or no symptoms at all.

For those who experience symptoms, it may take three to four weeks for them to appear after being exposed to the bacterium. This is referred to as the incubation period.

Common symptoms include:

  • Fatigue
  • Fever (low-grade)
  • Headache
  • Runny nose
  • Nasal congestion (stuffy nose)
  • Hoarse voice or loss of voice
  • Throat soreness
  • A cough that worsens over time


If you suspect you've come into contact with the bacteria or are experiencing symptoms, a healthcare provider may take a sample from your throat or nose to test for bacterial antibodies. A blood test to confirm infection is also possible.


Again, many people who have a Chlamydia pneumoniae infection will not need any specific treatment. The infection will often go away on its own.

If treatment is necessary, a healthcare provider can assess the infection and possibly prescribe antibiotics. Common antibiotics for adults include:

  • Azithromycin
  • Tetracycline
  • Doxycycline
  • Fluoroquinolones

Some people may go through one round of antibiotic treatment, but their symptoms come back after they are done taking the prescribed medicine. If this is the case, a healthcare provider may recommend another course of treatment.


Whereas many people who become infected have mild symptoms or no symptoms at all, some people experience an infection that can require hospitalization. This type of bacteria may make asthma worse and cause swelling in the brain (encephalitis) or heart (myocarditis).

Some research suggests that C. pneumoniae can also cause persistent infection. While persistent infection has not been definitively demonstrated in humans, it is hypothesized to play a role in chronic inflammatory conditions, including asthma and reactive arthritis.


Like many other bacterial pathogens, one of the best strategies to prevent infection is practicing good hygiene.

You can reduce the risk of passing bacteria to others by:

  • Coughing or sneezing into your elbow to stop the respiratory droplets from traveling
  • Properly disposing of any used tissues after blowing your nose

Hand hygiene is also a key component of prevention, including:

  • Washing your hands frequently and adequately with soap and warm water for at least 20 seconds
  • Using hand sanitizer containing at least 60% alcohol when you can't wash your hands
  • Not touching your eyes, nose, and mouth with unwashed hands

Note that healthcare providers won't typically prescribe antibiotics as a preventive measure against C. pneumoniae. It's also possible for it to recur.


Chlamydia pneumoniae is a species of Chlamydia that causes respiratory conditions, including pneumonia. It's transmitted from one person to another in close and prolonged contact through respiratory droplets. Symptoms may take up to four weeks to appear and can include sneezing, coughing, fatigue, low-grade fever, runny or stuffy nose, headache, and throat soreness.

Many people have mild or no symptoms, but older people are at a higher risk for severe infection. A throat swab or blood test may be used to diagnose an infection. If treatment is necessary, a healthcare provider will often prescribe antibiotics. It's possible for infection to recur after treatment.

Prevention measures typically include frequent handwashing and covering your coughs and sneezes to limit transmission to others.

A Word From Verywell

Though C. pneumoniae is typically transmitted through prolonged contact with a person who is infected, it's wise to regularly practice hygiene strategies to reduce the risk of any respiratory infections. Frequent handwashing is a key component of preventing many types of illnesses. Other practices include eating a nutritious diet, getting enough quality rest, managing your stress, and being regularly active, which can all help maintain your immune system so you're able to fight off infections.

Frequently Asked Questions

  • Is Chlamydia pneumoniae an STD?

    No. Chlamydia pneumoniae is not a sexually transmitted infection (STI). It's primarily spread through respiratory droplets. However, another species of Chlamydia, Chlamydia trachomatis, is sexually transmitted.

  • Is Chlamydia pneumoniae curable?

    Yes. Chlamydia pneumoniae can be treated and cured with antibiotics. For many people, the infection will go away on its own without treatment. It's possible to become infected again as a previous infection doesn't seem to result in immunity later on.

  • What are the signs and symptoms of Chlamydia pneumoniae?

    Common symptoms of Chlamydia pneumoniae are similar to other respiratory infections. You may experience fatigue, headache, low-grade fever, throat soreness, hoarseness in your voice, coughing, sneezing, and a runny or stuffy nose.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Centers for Disease Control and Prevention. Fast facts you need to know about chlamydia pneumoniae infections.

  3. Centers for Disease Control and Prevention. Chlamydia pneumoniae: causes, how it spreads, and risk factors.

  4. Centers for Disease Control and Prevention. Signs and symptoms of chlamydia pneumoniae infection.

  5. Centers for Disease Control and Prevention. Diagnosis, treatment and complications of chlamydia pneumoniae infection.

  6. Centers for Disease Control and Prevention. Chlamydia pneumoniae treatment.

  7. Porritt RA, Crother TR. Chlamydia pneumoniae infection and inflammatory diseasesFor Immunopathol Dis Therap. 2016;7(3-4):237-254. doi:10.1615/ForumImmunDisTher.2017020161

  8. Centers for Disease Control and Prevention. Preventing chlamydia pneumoniae infection.

  9. American Academy of Pediatrics. Chlamydia pneumoniae infections.

By Katie Wilkinson, MPH, MCHES
Katie Wilkinson is a public health professional with more than 10 years of experience supporting the health and well-being of people in the university setting. Her health literacy efforts have spanned many mediums in her professional career: from brochures and handouts to blogs, social media, and web content.