Chlamydia Pneumoniae

Is it the Same Type of Chlamydia as the STI?

'Chlamydia pneumoniae' – quite a confusing name given that there are separate diseases called 'chlamydia' and 'pneumonia'. So what is this weird combination disease all about?

It may sounds like it's related to the STI 'chlamydia' but there might be less overlap than you expected. Even so, Chlamydia pneumoniae is still worth understanding and looking out for.

What is Chlamydia Pneumoniae?

Chlamydia pneumoniae is type of bacteria – it causes lung infections, including pneumonia. It’s a very common infection, affecting about 50% of people by age 20 and 70-80% at age 60-70. Pneumonia doesn’t mean pneumonia – pneumonia is just one type of lung infection that it can cause. Not everyone who is exposed to the bacteria will develop pneumonia. How is it passed on? – anyone who is sick with an infection caused by Chlamydia pneumoniae will have the bacteria stored in in their nose, throat and lungs. Infectious bacteria is passed between people, for example if you breathe in the bacteria sneezed out by someone who has the infection.

Chlamydia pneumoniae and the STI known as chlamydia are not the same thing – these 2 infections won’t have the same effect on you. They have similar names because they are both from the same group of species (genus) called chlamydia. The STI chlamydia is caused by a different bacteria – the species called Chlamydia trachomatis, whereas Chlamydia pneumoniae is the species of bacteria that causes respiratory infections. There are both still infectious diseases – both types of infection are transmitted from person-to-person. However, the STI chlamydia is transmitted via sexual contact, whereas Chlamydia pneumoniae tends to be caused by other forms of close physical contact (e.g. being sneezed on by someone who has the infection). The treatment for your infection will vary depending to the specific type of chlamydia causing it.

What are the Symptoms of Chlamydia Pneumoniae?

Like the STI, Chlamydia pneumonia doesn’t show symptoms in most people – most people who have Chlamydia pneumoniae are ‘asymptomatic’, meaning that they don’t show signs or symptoms at all, or they only have very mild symptoms.Possible symptoms – if you do show symptoms, these can take at least 21 days since the date you were exposed to the bacteria to show up. Common symptoms are:

  • A blocked or runny nose
  • Tiredness
  • A mild fever
  • Sore throat or hoarseness
  • A bad cough
  • Headaches
  • An upper respiratory tract infection (like ear or sinus infections) 
  • Serious lung infections (like bronchitis or pneumonia) – these can develop, but this is much more common in older adults aged over 65. If you ever start showing the signs of a serious lung infection, you should visit your doctor for more advice and seek urgent medical help if the symptoms are severe. Symptoms of pneumonia typically include: 
  • Either a dry or mucous cough
  • Breathing problems
  • Fever, sweating and shivering
  • Chest pain
  • Loss of appetite
  • Confusion
  • Laryngitis (losing your voice) – this is sometimes a sign of pneumonia that is caused by Chlamydia pneumoniae bacteria. It isn’t a typical symptom of pneumonia caused by other types of bacterial infection.

    What are the Health Risks?

    The short-term risks of Chlamydia pneumoniae are mainly the symptoms listed above. These should settle down with suitable treatment, like antibiotics. If it’s left untreated – without treatment, Chlamydia pneumoniae can cause exacerbations and progression of Chronic Obstructive Pulmonary Disease (COPD), such as:

  • Emphysema
  • Chronic bronchitis
  • Refractory asthma
  • The risks vary from person to person – some people will be at higher risk of developing chronic health conditions than others. Talk to your doctor if you’re concerned about the health risks of Chlamydia pneumoniae, and what you can do to help reduce these risks.

    How is Chlamydia pneumoniae treated?

    Normally with antibiotics – the standard treatment for Chlamydia pneumoniae is a course of antibiotics, which are medicines that target specific bacteria in the body. Antibiotics tend to be the most effective form of medical treatment for the infection, and there are several different types of antibiotics that can be used. 
    Recovering without treatment – many people with the infection will recover without any medical treatment at all, but everyone reacts differently to infection. 
    It’s always worth getting help – if you are showing the signs of a chlamydia pneumoniae infection, and you suspect that you have been in close contact with someone who is currently sick with it, you should make an appointment with your local nurse or GP for an assessment. 
    In order to properly diagnose the infection, you will either have: 

  • A blood test

  • Or a swab test (using a sample from your nose or throat)

  • With treatment, you should start to notice your symptoms disappear within a couple of weeks – however, there is always the chance that your symptoms will reappear. In these cases, your doctor may decide to put you on a secondary course of treatment (although this is usually best avoided). 

    How Can You Avoid Getting it?

    It can be hard to avoid – like other respiratory infections, Chlamydia pneumonia is spread from person to people, when someone who is sick coughs or sneezes in close contact with another person, and they breathe in the bacteria. There is no vaccine or immunisation treatment to prevent the infection – this means that it’s incredibly important to practice good personal hygiene at all times in order to protect yourself and others from the bacteria. For example, by:

  • Regularly washing your hands with soap and water
  • Sneezing into a tissue, or away from others (if you have no tissue)
  • Safely throwing away any used tissues
  • Covering your mouth when you cough
  • The best tip is to avoid close contact with anyone who is sick with a Chlamydia pneumoniae infection – if you cannot avoid close contact with someone sick, ask your doctor for more advice on how to minimise your risk of getting infected. They may recommend that you wear a mask or gloves for a short time, or give you a form of preventative treatment in rare cases.You shouldn’t get sick if you’ve only spent a short amount of time with someone who is infected with Chlamydia pneumoniae. Who is more likely to get it? – anyone of any age can get sick from Chlamydia pneumoniae. However, first-time infections are much more common in children and young adults. Reinfections with the bacteria are most common in older adults.Workplace exposure – you will be at higher risk of infection if you live or work regularly in very crowded places, which is where outbreaks of Chlamydia pneumoniae usually occur. These include: 
  • Hospitals
  • Prisons
  • Schools
  • Shared accommodation (like family homes or student halls)
  • Nursing homes 
  • Age and risk – you are slightly more likely to get complications due to Chlamydia pneumoniae (like pneumonia) if you are aged 65 and above. Talk to your nurse or doctor if you are concerned about your risk of getting infected or developing complications from a Chlamydia pneumoniae infection. 


    Blasi, F., Tarsia, P. and Aliberti, S (2009). Chlamydophila pneumoniae. Clinical Microbiology and Infection, Jan; 15(1): 29-35.

    Centers for Disease Control and Prevention (2016). Chlamydia pneumoniae infection. CDC. [online] Available at: [accessed 3rd May 2018].

    Miyashita, N. (2006). Chlamydia pneumoniae infections. Kekkaku, Sep; 81(9): 581-8.

    NHS Choices (2016). Pneumonia. NHS. [online] [accessed 3rd May 2018]

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