Intensive Care Medicine (ICM) Practice Exam

What key factor increases the risk of atypical pneumonias?

1. Obesity

2. Smoking

3. Elderly age

4. Immunosuppression

The correct answer is: Smoking

The key factor that significantly increases the risk of atypical pneumonias is immunosuppression. Atypical pneumonias, often caused by organisms such as Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella species, can more readily affect individuals with compromised immune systems. This is because their bodies are less capable of mounting an effective immune response against these pathogens. In immunosuppressed patients—whether due to medical conditions, medications (like corticosteroids or chemotherapy), or advanced age—the normal defense mechanisms that would typically help clear infections are impaired. As a result, these individuals are at higher risk not only for atypical pneumonia but also for other types of infections, as their immune responses are weakened. While factors such as obesity, smoking, and elderly age can influence overall health and increase susceptibility to various infections and respiratory diseases, immunocompromised states specifically create environments where atypical pathogens can thrive and lead to severe disease outcomes.