How are different types of pneumonia classified?

Photo of a doctor listening to a patient’s lung
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Doctors classify different types of into various groups. This allows them to describe the disease more exactly, and more importantly, to start off with the correct treatment.

The various types of are classified according to a number of characteristics. To treat these types, it's essential to know whether somebody caught at home, in a hospital, or in a nursing home.

Community-acquired and nosocomial pneumonia

If you develop at home, it's referred to as community-acquired (or CAP for short), even if you are admitted to the hospital during the course of the illness.

If you develop while in the hospital, it is called hospital-acquired (HAP for short) or nocosomial . Pneumonia is considered to be nocosomial if it starts at least two days after you are admitted to the hospital, or within three months of a hospital stay.

Doctors can also classify even more exactly, giving consideration to whether somebody became infected in a retirement or a nursing home, at a medical facility such as a dialysis center, or while receiving artificial respiration.

Why is classification important for the treatment?

Community-acquired is usually caused by pneumococci, whereas nocosomial is often connected with staphylococci, various intestinal , and special germs such as Pseudomonas aeruginosa. Some of those can be multi-resistant, meaning they are resistant to several . That is why different are usually need than for treating community-acquired .

Mild, moderate or severe pneumonia

To be able to provide the right treatment, doctors also classify community-acquired as mild, moderate or severe. They take the risk of complications into account as well.

Pneumonia is considered to be mild with no increased risk if the patient

  • is younger than 65 years old,
  • is conscious and lucid,
  • has normal blood pressure and pulse,
  • is not breathing too fast (fewer than 30 breaths per minute),
  • has enough oxygen in their blood,
  • has not been given any in the past three months,
  • has not been in the hospital in the past three months, and
  • does not have any other severe medical conditions.

People with mild can be treated at home and are given antibiotics in tablet form.

The signs of moderate include drowsiness and confusion, low blood pressure, worsening shortness of breath, and risk factors such as old age and underlying diseases. People with these symptoms need to have treatment at a hospital. Some will be given a combination of two different , at least at the beginning of the treatment.

Pneumonia is classified as severe when the heart, the kidneys or the circulatory system are at risk of failing, or if the lungs can no longer take in enough oxygen. Treatment with an antibiotic infusion in intensive care is then usually needed, sometimes with artificial respiration or additional drugs such as corticosteroids.

Pneumonia in children is only classified as either “not severe” or “severe.”

How can pneumonia be described more exactly?

Experts also classify according to factors other than where the patient was infected and the severity. But that typically doesn't affect how the is treated. Instead, it's useful for getting a better description of the illness.

Atypical pneumonia

Typical generally begins with a sudden high fever and chills, and then coughing with phlegm coming later.

Atypical is caused by other germs, which are also referred to as "atypical." Older people in particular have fewer or slightly different symptoms if they have atypical : It then starts off rather slowly with a mild fever and/or headache and aching limbs. Rather than coughing with phlegm, they have a dry, tickly cough.

Atypical symptoms don't mean that the lungs are less severely inflamed or that the disease will take a milder course though.

Upper, middle and lower lobe pneumonia

X-rays play an important role in distinguishing between these types: the term lobar is used if an entire lung lobe is visibly inflamed. Depending on which lung lobe is affected, the is referred to as upper, middle or lower lobe .

If there are several multi-lobe focal inflammations in the lungs, the term focal is used. Some people use the term bronchopneumonia if the focal inflammations started in inflamed airways ().

Sometimes, it's the air sacs that are more inflamed (alveolar ), and sometimes it's the tissue between the sacs (interstitial ).

Deutsche Gesellschaft für Allgemeinmedizin und Familienmedizin (DEGAM). DEGAM-Leitlinie Nr. 11: Husten. AWMF-Registernr. 053-013. February 2014.

Deutsche Gesellschaft für Pädiatrische Infektiologie (DGPI), Gesellschaft für Pädiatrische Pneumologie (GPP). S2k-Leitlinie „Management der ambulant erworbenen Pneumonie bei Kindern und Jugendlichen (pädiatrische ambulant erworbene Pneumonie, pCAP)“. AWMF-Registernr.: 048-013. March 2017.

Deutsche Gesellschaft für Pneumologie und Beatmungsmedizin (DGP). S3-Leitlinie: Behandlung von erwachsenen Patienten mit ambulant erworbener Pneumonie und Prävention – Update 2016. February 15, 2016.

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Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson JL, Loscalzo J. Harrison's Principles of Internal Medicine. New York: McGraw-Hill; 2015.

Lux LJ, Posey RE, Daniels LS, Henke DC, Durham C, Jonas DE et al. Pharmacokinetic/Pharmacodynamic Measures for Guiding Antibiotic Treatment for Hospital-Acquired Pneumonia. November 2014. (AHRQ Comparative Effectiveness Reviews; Volume 136).

National Institute for Health and Care Excellence (NICE). Pneumonia: Diagnosis and Management of Community- and Hospital-Acquired Pneumonia in Adults. December 03, 2014. (NICE Clinical Guidelines; Volume 191).

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Created on August 9, 2018
Next planned update: 2021

Authors/Publishers:

Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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