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Why does typical pneumonia occurs in alveolar space or in the interstitial tissue or space of the lung?

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Practicing since : 1992
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Hello , how are
I have a medical question which I cannot find on the WEB and iam sure that i will find it here :)
my question is doctor :
Why does typical pneumonia occupies or occurs in Alveolar space whilst atypical one conquers or occurs in the interstitial tissue or space of the lung?
I know its hard to find it on the WEB and this is the place where i can finde it .
And its important to have the good medical answer from you :) .

Thank You .
Posted Sat, 27 Oct 2012 in Lung and Chest disorders
Answered by Dr. Sadiq Mughal 3 hours later

Thanks for your medical question.

The typical pneumonia, which you are referring, is bacterial pneumonia.

Bacterial invaders typically cause intraalveolar (with in alveoli) exudation resulting in consolidation (solidification) of the pulmonary parenchyma called as pneumonia.

In contrast to changes in bacterial pneumonia, viruses and mycoplasma tend to evoke essentially interstitial inflammation, which properly should be referred as pneumonitis.

However long usage has sanctified the term viral and mycoplasma pneumonia, because they lack the characteristic intraalveolar exudation and consolidation seen with bacterial invasion, they are sometimes referred to by the curious name, primary atypical pneumonia.

Hope I answered the question to your satisfaction. For any further query, do post your follow up, I will be readily available for answer.

If you don't have any further query, close the discussion, accept the answerer and write review.

Above answer was peer-reviewed by
Follow-up: Why does typical pneumonia occurs in alveolar space or in the interstitial tissue or space of the lung? 8 hours later
Thank you Dr. XXXXXXX Mughal for the answer , However you have answerd me a part which is Bacterial invaders occurs within the intraalveolar space , viruses and mycoplasma tend to evoke essentially interstitial inflammation. and thats what i understod from the answer, please correct me if i was wrong .

On the other hand , i wanted to know how does bacteria occurs in the intraalveolar why isnt the viruses and/or mycobacterum ?

Thats what i have been working on to fined beside which is causing intraalveolar and which is causing interstitial which you have answerd me.

I hope that aim not causing any bother to you , Dr. XXXXXXX Mughal .

Regardes, To You.

Answered by Dr. Sadiq Mughal 26 hours later
Thanks for your follow up.

No, you are not bothering me. Our aim at health care magic is to serve people.
I am happy to know that you’re satisfied with one part of my answer.
For understanding second part of your question, we have to understand following factors
No 1. Size and structure of viruses and mycoplasama
No2. Size of bacteria
No 3.Structure of Respiratory membrane.

Mycoplasma is the smallest and simplest replicating microorganism known and is about 0.1 um in diameter and belongs to a class of microbial prokaryotic cells that lack of cell wall.
It is a minute filament and has one differentiated pole, where a specialized adhesive ( PI) mediates attachment to receptor at epithelial cell of respiratory membrane.
Production of peroxide and inhibition of host cell catalase are thought to manage mediators of epithelial cell injury, facilitating their entry into interstitial space, where further inflammatory process takes place.
Viruses are much smaller than bacteria. Most viruses that have been studied have diameter of 20 to 300 nanometer, so easy for them to pass respiratory membrane.

Respiratory membrane:
It is the membrane which is between alveoli one side and pulmonary capillary on other side. This is the membrane through which oxygen, carbon dioxide, and other gases pass.
Viruses ,mycoplasma and bacteria (in case of bacteremia, a condition where the bacteria spread through the blood) also pass through this membrane.
The respiratory membrane itself is 0.2 µm. Bacteria range in size from 0.2 to 2 µm. and their usual size is 1 to 10 µm.
So how difficult for bacteria is to pass through respiratory membrane, exception being the inflammatory process which increases permeability of respiratory membrane.

Hope I explained the difficult process to some extent.

Let me know if you have any more concerns

Above answer was peer-reviewed by
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