All of the following organisms cause interstitial pneumonia except –
**Core Concept**
Interstitial pneumonia is a type of lung inflammation that affects the interstitial spaces of the lungs, including the alveoli, bronchioles, and lung parenchyma. It can be caused by various pathogens, including bacteria, viruses, fungi, and parasites.
**Why the Correct Answer is Right**
Interstitial pneumonia can be caused by a variety of organisms, including Mycobacterium tuberculosis (TB), Pneumocystis jirovecii (formerly known as Pneumocystis carinii), and Cryptococcus neoformans. These organisms typically cause an inflammatory response in the interstitial spaces of the lungs, leading to symptoms such as cough, shortness of breath, and chest pain.
**Why Each Wrong Option is Incorrect**
**Option A:** This organism typically causes lobar pneumonia, which is a different type of lung inflammation that affects the lobes of the lungs. It is not typically associated with interstitial pneumonia.
**Option B:** This organism is not typically associated with interstitial pneumonia, and its primary mode of infection is through the bloodstream rather than the respiratory tract.
**Option C:** This organism is a common cause of pneumonia in immunocompromised patients, but it typically causes a more severe form of pneumonia known as pneumocystis pneumonia (PCP), which affects the alveoli rather than the interstitial spaces.
**Clinical Pearl / High-Yield Fact**
In patients with interstitial pneumonia, it's essential to consider the possibility of opportunistic infections, particularly in those with underlying immunocompromised conditions.
**Correct Answer:** D.