What is Atypical Pneumonia?

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  • Written By: Tricia Ellis-Christensen
  • Edited By: O. Wallace
  • Last Modified Date: 25 December 2016
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Atypical pneumonia is distinguished from typical pneumonia because it has different causal agents than what is generally expected to produce pneumonia. Many types of typical pneumonia result from bacterial contagion with bacteria like streptococcus. Viruses, fungal infection, bacteria or other elements can cause forms of atypical pneumonia, which varies in severity.

Many sources identify atypical pneumonia as viral, or they speak only of pneumonia caused by mycoplasma, which is sometimes called walking pneumonia. While it’s correct to identify mycoplasma pneumonia as an atypical type, there are plenty of other types that need to be considered when making diagnosis. These include the severe pneumonia that can develop from Legionella bacteria. Other types are caused by Clamydiophila pneumoniae, a form of parasite, Coxiella burnetii, and Francisella tularensis.

These last types of microorganisms are relatively rare, but mycoplasma infections certainly are not. This explains why medical references may list mycoplasma as the principal cause of atypical pneumonia. Doing so does leave out potential other causes.


Given the diverse types of sources that may result in atypical pneumonia, symptom expression could have significant range. Most people would have difficult breathing and pronounced coughing, and some will have fevers. White blood cells may range lower then they do in typical pneumonia and are usually near normal in levels. One indicating factor is that response to the average antibiotic tends to be poor and most people won’t improve on drugs like penicillin. Some people, especially those with mycoplasma, may improve without drug treatment or they respond better when given medicines most adapted to fight mycoplasma.

Since atypical pneumonia can include extremely serious forms of pneumonia, treatment could be very different. Those suspected of having pneumonia caused by Legionella require different antibiotics. Despite the seriousness of this illness, many people benefit from antibiotics and can make a full recovery from the disease. Contrary to popular belief, human to human transmission of this disease isn’t possible, unless the germs are able to contaminate a water source and be released in a mist form. This is unlikely to occur in most settings.

Any symptoms of pneumonia like severe coughing, difficulty breathing, high fever, and a sense of being completely exhausted, represent a real medical concern. People should seek doctor advice and they might have a physical examination and chest x-ray. Whether or not atypical pneumonia is diagnosed at this stage is variable. An x-ray showing accumulation of fluid in the lungs with a normal white blood cell could be an indication.

Sometimes the fact that pneumonia is atypical is missed, and in this case, patients should pay attention to how symptoms are improving on standard antibiotics. On the other hand, some doctors recommend antibiotics that are useful in treating typical and atypical pneumonia. If symptoms don’t seem to be improving, patients should not hesitate to contact their doctors. Other treatment may be indicated.


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Post 3

The biggest issue with atypical pneumonia is that if it's misdiagnosed, the treatment may not work and it could cause complications to occur. Some doctors do still prescribe antibiotics for atypical pneumonia because it is believed that other types of infections can also turn into bacterial infections. So it is given as a precautionary measure. But antibiotics aren't really going to help with viruses or fungi or parasites unless there are bacteria present and contributing to the condition as well.

Post 2

@serenesurface-- I think this confusion occurs because many of us don't know what pneumonia means as a term. I too learned this recently after suffering from atypical pneumonia.

Pneumonia is not the name of the infection. Pneumonia is lung inflammation and involve pus filling up air sacs in the lungs. The cause of the inflammation is infection and the infection can be cause by any microorganism. It's true that bacterial and viral infections causing pneumonia are most common. So these are considered typical and other types of infections are atypical. Mine was caused by a fungal infection for example.

Post 1

I always thought that pneumonia just means a serious viral infection. I had no idea that it has so many possible causes. How is this possible? So I guess anything that's not bacterial or viral pneumonia is atypical? But which kind is worst or most dangerous?

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